Determination of complex compounds. Chemistry lesson "Complex compounds". The main provisions and concepts of coordination theory

State Educational Institution of Higher Professional Education

"Samara State University of Communications Communications"

Ufa Institute of Communications

Department of General Education and Professional Disciplines

A summary of lectures on the discipline "Chemistry"

on the topic: "Complex Connections"

for students of 1 course

railway specialties

all forms of learning

Compiler:

A summary of the lecture on the discipline "Chemistry" on the topic "Complex compounds" for students of 1 course of railway specialties of all forms of training / compiler :. - Samara: Samgups, 2011. - 9 s.

Approved at the meeting of the Department of OIPD 03/23/2011, Protocol

Printed by the decision of the Editorial Publishing Council of the University.

Compiler:

Reviewers: head. Department "General and Engineering Chemistry" Samgups,

d. Kh.N., Professor;

associate Professor of the Department "General and Inorganic Chemistry" BSU (Ufa),

Signed in print 04/07/2011. Format 60/901/16.

Paper writing. Print operational. Sl. Pechs. l. 0.6.

Circulation 100. Order number 73.

© Samara state University Communication paths, 2011

The content of the lectures corresponds to the state General Education Standard and requirements of higher education to a mandatory minimum content and level of knowledge of graduates higher School According to the cycle "Natural science disciplines". Lecture is set out as a continuation Chemistry lectures For students of railway specialties of the 1st year of all forms of training drawn up by the team of the Department "General and Engineering Chemistry"

The lecture contains the main provisions of the theories of the chemical bond, the stability of the complexes, the range of complex compounds, examples of solving problems. The material set out in the lecture will be useful when studying the topic "Complex compounds" by students of day and correspondence forms of training and in solving control tasks by students of the correspondence department of all specialties.

This publication is located on the website of the Institute.

Complex compounds

Education of many chemical compounds It occurs in accordance with the valence of atoms. Such compounds are called simple or first-order compounds. At the same time, very many compounds are known, the formation of which cannot be explained on the basis of the rules of valence. They are formed by combining simple compounds. Such compounds are called higher order compounds, complex or coordination compounds. Examples of simple compounds: H2O, NH3, AGCL, CUSO4. Examples of complex compounds: AGCL 2NH3, CO (NO3) 3 6NH3, ZNSO4 4H2O, FE (CN) 3 3KCN, PTCl2 2kci, PDCL2 2NH3.

The ions of some elements have the ability to attach polar molecules or other ions, forming complex complex ions. Compounds in which comprehensive ions are capable of exist both in a crystal and solution are called complex compounds. The number of well-known complex compounds is many times the number of simple compounds familiar to us. Complex compounds have been known for more than a century ago. As long as the nature of the chemical bond, the causes of their formation were established, the empirical formulas of the compounds were recorded as we indicated in the examples above. In 1893, the Swiss Chemist Alfred Werner proposed the first theory of the structure of complex compounds, the name of the coordination theory. Complex compounds make up the most external and diverse class of inorganic substances. Many elementogenic compounds also own them. The study of the properties and spatial structure of complex compounds gave rise to new ideas about the nature of the chemical bond.

1. Coordination theory

The following structural elements are distinguished in the complex compound molecule: ion-complexing agent coordinated around it the attached particles - ligandsconstituting together with the complex inner coordination sphere, and the remaining particles included in foreign coordination sphere. When dissolved complex compounds of ligands remain in solid connection with an ion-complexing agent, forming almost undervisiting the complex ion. The number of ligands is called coordination number (c.).

Consider the potassium ferrocyanide K4 is a complex compound forming when interacting 4KCN + FE (CN) 2 \u003d K4.

When dissolved, a comprehensive compound dissociates to ions: K4↔4K ++ 4-

Characteristic complexes: Fe2 +, FE3 +, CO3 +, CR3 +, AG +, Zn2 +, Ni2 +.

Characteristic ligands: CL-, BR-, NO2-, CN-, NH3, H2O.

The charge of the complex theater is equal to the algebraic amount of charges of the components of its ions, for example, 4-, x + 6 (-1) \u003d - 4, x \u003d 2.

Neutral molecules included in the complex ion have influence on the charge. If the entire internal sphere is filled with only neutral molecules,

that charge of the ion is equal to the charge of the complexing agent. So, at ion 2+, the charge of copper X \u003d + 2.

The charge of an integrated ion is equal to the amount of charge charges in the outer sphere. In K4, the charge is -4, since 4k + is located in the outer sphere, and the molecule as a whole is e-mail. Perhaps the mutual substitution of ligands in the inner sphere while maintaining the same coordination number, for example, CL2, CL ,. Cobalt ion charge is +3.

Nomenclature of complex compounds

In the preparation of the names of complex compounds, the anion is first indicated, and then in the parental case - the cation (like simple compounds: potassium chloride or aluminum sulfate). In brackets, the Roman digit indicates the degree of oxidation of the central atom. Ligands are referred to as follows: H2O - Aqua, NH3 - ammin, C1-cN-CN - - cyano, SO4 2- - sulfato - etc. We call the above compounds A) AGCL 2NH3, CO (NO3) 3 6NH3, ZNSO4 4H2O; b) Fe (CN) 3 3KCN, PTCL2 2KCI; c) PDCl2 2NH3.

With complex cation a): Diammininserbra (I) chloride, hexammingobalt nitrate (III), Tetrakvycinic Sulfate (P).

FROM complex anion b): Hexacyanoferrat (III) potassium, potassium tetrachloroplatotinate (II).

Complex- non-election c): Dichlorodammmedia.

In the case of non-electrolytes, the name is built in the nominative case and the degree of oxidation of the central atom is not indicated.

2. Methods for establishing coordination formulas

There are a number of methods for establishing coordination formulas of complex compounds.

Using double exchange reactions. It was this way that the structure of the following complex compounds of platinum was proved: PTCl4 ∙ 6NH3, PTCl4 ∙ 4NH3, PTCl4 ∙ 2NH3, PTCl4 ∙ 2KCl.

If you act on a solution of the first compound with a solution of AGNO3, then the entire chlorine contained in it is precipitated as silver chloride. Obviously, all four chloride ions are in the external sphere and, therefore, the inner sphere consists of only Ammonia ligands. Thus, the coordination compound formula will be CL4. In the compound PTCl4 ∙ 4NH3 silver nitrate precipitates only half chlorine, i.e., in the outer sphere there are only two chloride ions, and the remaining two together with four ammonia molecules are part of the inner sphere, so the coordination formula has the form of CL2. The PTCL4 ∙ 2NH3 connection solution does not give a sediment with AGNO3, this compound is depicted by the formula. Finally, the ptcl4 ∙ 2kcl compound solution of silver is also not precipitated by AGCL, but by exchange reactions can be installed that potassium ions are available in the solution. On this basis, its structure is depicted by the formula K2.

On the molar electrical conductivity of dilute solutions. With a strong dilution, the molar electrical conductivity of the complex compound is determined by the charge and the number of formed ions. For compounds containing complex ion and single-charged cations or anions, the following approximate ratio takes place:

The number of ions for which disintegrates

electrolyte molecule

Λ (c), Om-1 ∙ cm2 ∙ mole-1

Measuring the molar electrical conductivity λ (c) in a row of complex compounds of platinum (IV) allows the following coordination formulas: CL4 - dissociates with the formation of five ions; CL2 - three ions; - neutral molecule; K2 - three ions, two of which potassium ions. There are also a number of other physicochemical methods for establishing coordination formulas for complex compounds.

3. Type of chemical bond in complex connections

a) electrostatic representations .

The formation of many complex compounds can be explained in the first approximation to electrostatic attraction between the central cation and anions or polar molecules of ligands. Along with the forces of attraction, the forces of electrostatic repulsion are also valid between the charged ligands of the same name. As a result, a steady grouping of atoms (ions) is formed, which has a minimum potential energy. The complexing agent and ligands are treated as charged non-deformed balls of certain sizes. Their interaction is taken into account by the law of the coulon. Thus, the chemical relationship is considered ion. If ligands are neutral molecules, then in this model, the ion-dipole interaction of a central ion with a polar molecule of the ligand should be taken into account. The results of these calculations satisfactorily transmit the dependence of the coordination number from the charge of the central ion. With increasing charge of the central ion, the strength of complex compounds increases, an increase in its radius causes a decrease in the strength of the complex, but leads to an increase in the coordination number. With increasing size and charge of ligands, the coordination number and stability of the complex decrease. The primary dissociation proceeds almost aimed by the type of dissociation of strong electrolytes. Ligands in the inner sphere are associated with a central atom much stronger, and split only to a small extent. The reversible decay of the internal sphere of the complex compound is called the secondary dissociation. For example, the dissociation of the CL complex can be written as follows:

CL → ++ CL - primary dissociation

+ ↔ag ++ 2NH3 Secondary Dissociation

However, the simple electrostatic theory is not able to explain the selectivity (specificity) of complexation, since it does not take into account the nature of the central atom and ligands, the features of the structure of their electronic shells. To account for these factors, electrostatic theory was supplemented polarization Representations according to which the complexation is conducive to participating as the central atoms of small multiple-charged cations of D-elements with a strong polarizing action, and as ligands - large, easily polariate ions or molecules. In this case, there is a deformation of the electronic shells of the central atom and ligands, leading to their interpenetration, which causes the strengthening of relations.

b) The method of valence relationships.

In the method of valence bonds, it is assumed that the central atom of the complexing agent should have free orbitals for the formation of covalent bonds with ligands, the number of which determines the maximum value of the complex. In this case, a covalent σ-bond occurs when the free orbital of the complex of the complexing agent is overlapped with filled donor orbitals, i.e., containing vapor-free pairs of electrons. This connection is called coordination relationship.

Example1. Complex ion 2+ has a tetrahedral structure. What orbital complexes are used to formulate communication with NH3 molecules?

Decision. The tetrahedral structure of molecules is characteristic of the formation of SP3 hybrid orbital.

Example2. Why is the complex ion + has a linear structure?

Decision. The linear structure of this ion is a consequence of the formation of two hybrid SP orbitals by the Cu + ion, which is received by the NH3 electronic pairs.

Example3.. Why is Ion 2-paramagneticity, and 2-diamagnetic?

Decision. CL ions - weakly interact with Ni2 + ions. Chlorine's electronic pairs enter the orbital of the next vacant layer with n \u003d 4. At the same time, 3D nickel electrons remain unpaid, which causes paramagnetism 2-.

In 2- as a result of DSP2 hybridization, electron and ion diamagnetic

c) the theory of the crystal field.

The theory of the crystal field considers the electrostatic interaction between the positively charged metal-complex meter ions and watered electron vapors of the ligands. Under the influence of the ligand field, the d-levels of the transition metal ion occurs. Usually there are two configurations of complex ions - octahedral and tetrahedral. The magnitude of the splitting energy depends on the nature of the ligands and the configuration of the complexes. Calculation by electrons of the split D-orbits is made in accordance with the Rule of Hinda, with ions OH-, F-, CL - and H2O molecules, NO are ligands of a weak field, and the ions CN-, NO2 and CO molecule - the ligands of a strong field significantly splitting D-levels of the complexing agent. The splitting circuits of D-levels in octahedral and tetrahedral fields of ligands are given.

Example1. Pail with titanium electron distribution in octahedral complex ion 3+.

Decision. Paramagnetic ion in accordance with the fact that there is one unpaired electron localized on the Ti3 + ion. This electron occupies one of the three degenerate Dε orbitals.

When the light is absorbed, the electron transition is possible with Dε- on the DY-level. Indeed, ion 3+, having a single electron on Dε orbital, absorbs light with a wavelength λ \u003d 4930Å. This causes staining of diluted solutions of Ti3 + salts into an additional to absorbed purple color. The energy of this electronic transition can be calculated by the ratio

https://pandia.ru/text/78/151/images/image002_7.png "width \u003d" 50 "height \u003d" 32 src \u003d "\u003e; e \u003d 40 kcal / g ∙ ion \u003d 1.74 eV \u003d 2, 78 ∙ 10-12 ERG / ion. Substituting in the formula for calculating the wavelength, we get

Div_adblock332 "\u003e

In this case, the constant of the equilibrium in this case is called the constant of the invalid of the complex ion https://pandia.ru/text/78/151/images/image005_2.png "width \u003d" 200 "height \u003d" 36 src \u003d "\u003e solving this equation, we find x \u003d 2.52 ∙ 10-3 g ∙ ion / l and, therefore, \u003d 10.1 ∙ 10-3 mol / l.

Example. Determine the degree of dissociation of the complex ion 2+ in 0.1 molar solution of SO4.

Decision. Denote by the concentration formed during the dissociation of a complex ion, through x. Then \u003d 4x, and 2 + \u003d (0,1- x) mol / l. We substitute the equilibrium concentrations of components to the equation Since H.<<0,1, то 0,1–х ≈ 0,1. Тогда 2,6∙10-11=256х5, х=2,52∙10-3 моль/л и степень диссоциации комплексного иона

α \u003d 2.52 ∙ 10-3 / 0.1 \u003d 0.025 \u003d 2.5%.

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When considering types of chemicals, it was noted that attraction forces arise not only between atoms, but also between molecules and ions. Such interaction can lead to the formation of new more complex complex (or coordination) compounds.

Complexcalled compounds having in the nodes of the crystal lattice the aggregates of atoms (complexes) capable of independent existence in solution and having properties other than the properties of the components of their particles (atoms, ions or molecules).

In the complex compound molecule (for example, K 4), the following structural elements distinguish: ion compound Education (for this FE complex), coordinated around it the attached particles - ligands or addden (CN -), components with the complexing agent inner coordination sphere (4-), and the remaining particles included in foreign coordination sphere (K +). In the dissolution of complex compounds of ligands remain in solid connection with an ion-complexing agent, forming almost no dissociating complex ion. The number of ligands is called coordination number (In the case of K 4, the coordination number is 6). The coordination number is determined by the nature of the central atom and ligands, and also corresponds to the most symmetrical geometric configuration: 2 (linear), 4 (tetrahedral or square) and 6 (octahedral configuration).

Characteristic complexes are cations: Fe 2+, Fe 3+, CO 3+, CO 2+, Cu 2+, Ag +, Cr 3+, Ni 2+. The requirements for the formation of complex compounds are associated with the electronic structure of atoms. Complex ions Elements of D-families are especially easy to form: AG +, AU +, CU 2+, HG 2+, Zn 2+, Fe 2+, CD 2+, Fe 3+, CO 3+, Ni 2+, Pt 2+, Pt 4+ and others. The complexes can be A1 3+ and some non-metals, for example, Si and V.

Ligands can serve as charged ions: F -, OH -, NO 3 -, NO 2 -, CL -, VG -, I -, CO 3 2-, CRO 4 2-, S 2 O 3 2-, CN -, PO 4 3-, etc., and electronic metering molecules: NH 3, H 2 O, PH 3, CO, etc. If all ligands in the complexing agent are the same, then the complex uniform connection, for example Cl 2; If the ligands are different, then the connection heterogeneous, for example cl. Between the complexing agent and ligands, coordination (donor-acceptor) communications are usually established. They are formed as a result of overlapping the ligand orbitals filled with electrons by vacant orbital atoms. In complex compounds, the donor is a complex of consultant, an acceptor - ligand.

The number of chemical bonds between the complexing agent and ligands determines the coordination number of the complexing agent. Characteristic coordination numbers: Cu +, Ag +, Au + \u003d 2; Cu 2+, Hg 2+, Pb 2+, Pt 2+, PD 2+ \u003d 4; Ni 2+, Ni 3+, CO 3+, A1 3+ \u003d 4 or 6; Fe 2+, Fe 3+, Pt 4+, Pd 4+, Ti 4+, Pb 4+, Si 4+ \u003d 6.

The charge of the complexing agent is equal to the algebraic amount of charges of the components of its ions, for example: 4-, x + 6 (-1) \u003d 4-; x \u003d 2.

Neutral molecules included in the complex ion do not affect the charge. If the entire inner sphere is filled with only neutral molecules, then the charge of the ion is equal to the charging of the complexing agent. So, ion 2+ charge copper x \u003d 2+. The charge of the complex ion is equal to the charges of ions in the outer sphere. In K 4, the charge is -4, since in the outer sphere there are 4 cations K +, and the molecule as a whole is e-mail.

Ligands in the inner sphere can replace each other while maintaining the same coordination number.

Classification and nomenclature of complex compounds. FROM points of view complete particle charge all complex compounds can be divided into cationic, anionic and neutral.

Cationic complexes metal cations form neutral or anionic ligands around themselves, and the total ligand charge is less than an absolute value than the degree of oxidation of the complexing agent, for example, Cl 3. Cationic complex compounds in addition to hydroxcomplexes and salts, may be acids, for example, hexafluorous acid.

IN anionic complexes , on the contrary, ligand anions such a number that the total charge of an integrated anion is negative, for example. IN anionic complexesas ligands are hydroxide anions - this hydroxocomplexes (for example Na 2 - potassium tetrahydroxotycinat), or anions of acid residues - it acidomplexes(for example, 3 - hexaciaranrat (III) potassium) .

Neutral complexes there may be several species: a complex of a neutral metal atom with neutral ligands (for example, nickel tetracarbonyl, [CR (C 6 H 6) 2] - Dibenzolch). In neutral complexes of another type of charges of the complexing agent and ligands, each other are balanced (for example, hexammamp chloride (IV), - trinitrotriamicobalt).

Classify complex connections can by nature ligand.Among compounds with neutral ligands, aquacomplexes, ammoniats, metal carbonyls are distinguished. Complex compounds containing water molecule as ligands call akvakompleksami . When crystallization of the substance from the solution, the cation captures a part of water molecules, which fall into the crystal salt grille. Such substances are called crystallohydratesfor example, A1C1 3. · 6N 2 O. Most of the crystallohydrates is aquacomplexes, so they are more accurately depicted in the form of a complex salt ([A1 (H 2 O) 6] C1 3 - hexacawalum chloride). Complex compounds with ammonia molecules as a ligand called ammonia , for example C1 4 - Hexammamp chloride (IV). Metal carbonyls called complex compounds in which the ligands serve as carbon oxide (II) molecules, for example, - pentarbonyl iron, - tetracarbonyl nickel.

Known complex compounds with two complex ions in the molecule, for which there is a phenomenon of coordination isomerism, which is associated with a different distribution of ligands between complexing agents, for example: - hexanicobaltate (III) hexamminnicel (III).

When compiling names of a comprehensive compound the following rules apply:

1) If the compound is a complex salt, then the first is called an anion in the nominative case, and then the cation in the parental case;

2) with the name of the complex ion, the ligands are first indicated, then the complexing agent;

3) Molecular ligands correspond to the names of molecules (except water and ammonia, the terms apply to the designation "aqua"and "amine");

4) End is added to the anionic ligands - o, for example: F - - fluoro, C1 - - chloro, o 2 - - oxo, CNS - - Rodano, NO 3 - - Nitrato, CN - - Cyano, SO 4 2- - Sulfato , S 2 O 3 2- - thiosulfato, CO 3 2- - carbonate, PO 4 3- - phosphato, it is hydroxy;

5) Greek numerals are used to designate the number of ligands: 2 - di-,3 –three-,4 –tetra-,5 –penta-,6 –hexa-;

6) if the complex ion is the cation, then the Russian name of the element is used for the name of the complexing agent, if Anion is Latin;

7) after the name of the complexing agent, the Roman number in parentheses indicate its oxidation degree;

8) In neutral complexes, the name of the central atom is given in the nominative case, and its degree of oxidation is not specified.

Properties of complex compounds.Chemical reactions involving complex compounds are divided into two types:

1) omnipher - with their flow, the complex particle remains unchanged (exchange reaction);

2) intrafer - when they flow, there are changes to the degree of oxidation of the central atom, in the structure of ligands or changes in the coordination sphere (decrease or increase in the coordination number).

One of the most important properties of complex compounds is their dissociation in aqueous solutions. Most water soluble ion complexes - strong electrolytes, they dissociate on the external and internal sphere: k 4 ↔ 4k + + 4 -.

Complex ions are sufficiently stable, they are weak electrolytees, stepwise split into an aqueous solution of Ligand:

4 - ↔ 3- + CN - (the number of steps is equal to the number of ligands).

If the total charge of the complex compound particle is zero, we have a molecule non-electrolyteeg .

In exchange reactions, complex ions are moving from some connections to others, without changing their composition. Electrolytic dissociation of complex ions is subject to the law of the active masses and quantitatively characterized by a dissociation constant that is called constants of obstacity To n. The smaller the instability constant of the complex, to a lesser extent it disintegrates on the ions, the more stable is the compound. Compounds characterized by high K H, complex ions are unstable, i.e. they are practically no in solution, such compounds are double salts . The difference between typical representatives of complex and double saline conclusions in the fact that the last dissoci-outer with the formation of all ions, which are part of this salt, for example: KA1 (SO 4) 2 ↔ K + + A1 3+ + 2SO 4 2- (double salt);

K ↔ 4K + + 4- (complex salt).

With 5. Ligands directly related to the complexing agent form together with it internal (coordination) sphere complex. Thus, in the complex cation 2+, the inner sphere is formed by an atom of the complexing agent - copper (II) and ammonia molecules, directly related to it. The inner sphere is indicated by square brackets: 3 , 2 , 2 . Depending on the ratio of the total charge of ligands and the complexing agent internal sphere may have a positive charge, for example, 3+, or negative, for example, 3 , or zero charge, for example, for 0.

Ions neutralizing the charge of the internal sphere, but not associated with the complexing agent covalently form foreign compound sphere. For example, in the complex compound Cl 2 two CL ions are located in the outer sphere:

Exodium ions CL  are located at a more significant distance from the complexing agent than NH 3 molecules, in other words, the distance zn - CL is larger than the length of the chemical bond Zn - N. Moreover, the chemical bond of the complex 2+ cation 2+ and CL chloride  has an ionic character, while ammonia molecules NH 3 entering into the inner sphere is formed with the Zn (II) complexion covalent bonds on the donor-acceptor mechanism (the donor of the reciprocal pairs of electrons is nitrogen atoms in NH 3). Thus, the difference between ligands of the inner sphere and ions of the external sphere Very substantial.

In (OH) 2 and K 2, the ions oh  and k + are respectively. It is quite clear that in neutral complexes 0 and 0 there is no external sphere.

With 5. Typically, the outer sphere makes up simple monatomic or multiatomic ions. However, there are cases when the COP consists of the two and more internal spheresperforming the functions of the cationic and anionic portion of the compound. Here each of the inner spheres is external with respect to the other. For example, in compounds and 2 formally, the functions of the external ions can be performed:

 Complex cations 2+ and 2+,

 Complex anions 2  and 4 

1.6. Multi-core complexes

With 8. If in the complex ion or neutral complex is contained two or more complexesthen this complex is called multi-core. Among the multi-core complexes allocate mostic, cluster and multi-core complexes mixed type.

The complexing agent atoms may be interconnected using bridging ligandsThe functions of which are performed by OH , Cl , NH 2 , O 2 2 , SO 4 2  and some others. So, in complex compound (NH 4) 2 bridging Serve bidentate (2 ties) hydroxide ligands:

When the atoms of the complexing agent are interconnected directly, the multi-core complex belongs to cluster type. So, the cluster is a complex anion 2 

in which is implemented four communication Re - Re:one σ-bond, two π- communications and one δ-link . Especially a large number of cluster complexes numbered among derivatives d.- elements.

Multi-core complexes mixed type Contain as communications compound consultation-complexing agent, so I. mostic Ligands. An example of a mixed type complex can serve as a carbonyl complex of cobalt composition having the following structure:

Here there is a single CO - CO bond and two bidentate carbonyl ligands CO, carrying out the bridal compound of atomic components.

Comprehensive compounds.

All inorganic compounds are divided into two groups:

1. Communication of the first order, ᴛ.ᴇ. compounds obeying valence theories;

2. Communication of higher order, ᴛ.ᴇ. United States, not subject to the concepts of valence theory. The sentence of higher order includes hydrates, ammonia, etc.

COCL 3 + 6 NH 3 \u003d CO (NH 3) 6 Cl 3

Werner (Switzerland) introduced into the chemistry of ideas about the joints of the highest order and gave them the name comprehensive compounds. To the COP, it will include the most stable compounds of the highest order, which in aqueous solution or do not disintegrate at all, or disintegrate. In 1893, Werner suggested that any element after saturation is able to exhibit also additional valence - coordination. According to the coordination theory of Verner, each COP is distinguished:

Cl 3: Complexedomator (CO \u003d CO), Ligands (NH 3), coordination number (CC \u003d 6), inner sphere, external medium (Cl 3), coordination container.

The central atom of the inner sphere, around which ions or molecules are grouped, is called called complexed former. The role of the complexeener is more often performed by metal ions, less often neutral atoms or anions. Ions or molecules coordinating around the central atom in the inner sphere are called ligands. Ligands There are anions: r -, O., CN-, CNS-, NO 2 -, CO 3 2-, C 2 O 4 2-, neutral molecules: H 2 O, CO, G 2, NH 3, N 2 H four . Coordination number - The number of places in the inner sphere of the complex, which are occupied by ligands. QC is usually higher than oxidation. KC \u003d 1, 2, 3, 4, 5, 6, 7, 8, 9, 12. Especially all are encountered KC \u003d 4, 6, 2. These numbers correspond to the most symmetric configuration of the complex - octahedral (6), tetrahedrical ( 4) and linase (2). Kch. The envy of the nature of the complexing agent and ligands, as well as from the size of the KO and ligands. Coordination capacity of ligands- the number of places in the inner sphere of the complex occupied by each ligand. For most ligands, coordination container is equal to one ( monodentnyeliganda), less than two ( bidentnyeliganda), there are ligands with a greater capacity (3, 4, 6) - polydentyeliganda. The charge of the complex numerically should be numerically equal to the total external sphere and is opposite to him by sign. 3+ Cl 3 -.

Nomenclature of complex connections. Many complex interconnections have retained their historical names associated with color or named by the scientist of their synthesizing. Today it is used by the nomenclature of the Jew.

The order of transfer of ions. The first to call Anion, then the cation, while the root of the Latin name of the Latin name is used in the name of the anion, and its Russian name is in the name of the cation.

CL - chloride diaminisserbra; K 2 - trichlorocouprat potassium.

Order of the list of ligands. Ligands in the complex are listed in the following order: anionic, neutral, cationic - without a defisc section. Anions are transferred in accordance with H -, O 2-, OH -, simple anions, complex anions, polyatomic anions, organic anions.

SO 4 - chlorofodimitsulfate (+4)

The end of the coordination groups.Neutral groups are also called molecules. The exceptions are Aqua (H 2 O), amine (NH 3). For negatively charged anions add vowels''o''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''

- hexocyanoferrat (+3) hexaamineacobalt (+3)

Consoles indicating the number of ligands.

1 - Mono, 2 - Di, 3 - three, 4 - Tetra, 5 - Penta͵ 6 - Hexa, 7 - Hepta͵ 8 - Octa͵ 9 - Nona, 10 - Deca, 11 - Indka, 12 - Dodec, Many - poly.

The bis-, tris- used before ligands with complex names, where the prefixes of mono-, di-, etc. are already available.

Cl 3 - TRIS chloride (ethylenediamine) of shipping (+3)

In the names of complex compounds, initially indicates the anion part in the nominative case and the suffix - and then the cationic part in the parental case. At the same time, before the title of the central atom, both in anionic and in the cationic part of the combination of ligands are listed, with an indication of their number Greek numeral (1 - mono (usually descended), 2 - di, 3 - three, 4 - tetra, 5 - penta͵ 6 - hex, 7 - hepta͵ 8 - Oct). Subfix -o is added to the names of ligands, and at first they call an anions, and then neutral molecules: SL- - chloro, CN- - cyano, Oxalato, C2O42- - oxalato, S2O32- - Tyosulfato, (CH3) 2NH - dimethylamino and etc. Exceptions: N2O and NH3 names as ligands are as follows:''Akva''' and''ammin' '. In the event that the central atom is part of the cation, then the Russian name of the element is used after which the Roman numerals indicate its degree of oxidation in brackets. For the central atom in the anion, the Latin name of the element is used and the degree of oxidation is indicated before this title. For elements with a constant degree of oxidation, it can be omitted. In the case of non-electrolytes, the degree of oxidation of the central atom does not indicate, since it is determined, based on the electronics of the complex. Examples of titles:

CL2 - Dichloro-Tetrammin-Platinum chloride (IV),

OH - Diammine-Silver hydroxide (I).

Classification of complex connections. There are several different COP classifications.

1. according to the identity class:

complex acids - H 2

complex bases -

complex salts - K 2

2. By nature ligands: Akvakompleks, ammonia. Cyanide, halide, etc.

Akvakompleks - complexes in which water molecules are led by ligands, for example, CL 2 is a hexacvaculation chloride. Ammonia and amindas are complexes in which the ligands are ammonia molecules and organic amines, for example: SO 4 - Tetrambammy sulfate (II). Hydroxocomplexes. In them, the ligands serve ions on-. Particularly characteristic of amphoteric metals. Example: Na 2 - Sodium tetragadroxycinat (II). Acidomplexes. In these complexes, ligands are anions-acid residues, for example K 4 - potassium hexaciatorrat (II).

3. the Sign of Charge of the Complex: cationic, anionic, neutral

4. According to the internal structure of the COP: in terms of the number of nuclei, the components of the complex:

mononuclear - H 2, dual-core - Cl 5, etc.,

5. In the absence or presence of cycles:simple and cyclic COP.

Cyclic or chelated (cylinder-shaped) complexes. ʜᴎʜᴎ contain bio or polydentateligand, which, as if captures a central atom m like a cancer tongue: Examples: Na 3 - trioxalate- (III) Sodium Ferrat, (NO 3) 4 - Treethylenediamine-Platinum nitrate (IV).

The group of chelate complexes includes intracomplex compounds, in which the central atom is part of the cycle, forming links with ligands in different ways: on exchange and donor-acceptor mechanisms. Such complexes are very characteristic of aminocarboxylic acids, for example, glycine forms chelates with Cu 2+ ions, Pt 2+:

Chelate compounds are distinguished by special strength, since the central atom in them is as if blocked by a cyclic ligand. Chelates with five and six-heed cycles have the greatest stability. The complexions are so firmly associated with metal cations, which, when adding, such poorly soluble substances are dissolved as CASO 4, BASO 4, CAC 2 O 4, CACO 3. For this reason, they are used to soften water, to bind metal ions when painted, processing photographic materials, in analytical chemistry. Many chelate type complexes have a specific color and in connection with this, the corresponding ligand compounds are very sensitive reagents on transition metal cations. For example, dimethyl glyoxime [C (CH 3) NOH] 2 serves as an excellent reagent on Ni2 +, Pd2 +, Pt2 +, Fe2 +, etc. cations.

Stability of complex compounds. Constant of obstacity.When dissolving the CS in water, the decay occurs, and the internal sphere behaves like a single whole.

K \u003d k + + -

Along with this process, the dissociation of the internal sphere of the complex occurs to a slight degree:

AG + + 2CN -

To characterize the Sustainability of the COP introduced constant of obstacityequal to:

Constant of disadvantacle - measure of the strength of the COP. The less thing is that, the more firmly the COP.

Isomerization of complex connections.For complex compounds, the isomerism is very common and distinguished:

1. The solvate isomerism is detected in isomers when the distribution of water molecules between the inner and external spheres turns out to be unequal.

Cl 3 Cl 2 H 2 O Cl (H 2 O) 2

Purple light green dark green

2. Ionization isomeria associated with different ease of dissociation of ions from the internal and external sphere of the complex.

4 Cl 2] br 2 4 br 2] Cl 2

SO 4 and Br - Sulfatbromo-Pentammin-cobalt (III) ibromife sulfate-pentammin-cobalt (III).

CLA NO 2 is chloride-chloro-diethylenediamine-cobalt (III) of etitrutdihloro-diethylenediami-cobalt (III).

3. Coordination isomeria occurs only at bicomponia

[CO (NH 3) 6] [CO (CN) 6]

Coordination isomeria It is found in those complex compounds, where both the cation and anion are complex.

For example, the tetrachloro-(II) Tetrachmmin-chromium platitz (II) and - tetrachloride (II) chromate Tetrammin-Platinum (II) are coordination isomers

4. Miscellaneous Communication It occurs only when monodentateligands can be coordinated through two different atoms.

5. Spatial isomeria due to the fact that the same ligands are located around (cis), or opposite ( trance).

Cis-Isomer (Orange Crystals) Trans-Isomer (Yellow Crystals)

Isomers Dichloro-Diammin-Platinum

With a tetrahedral location, ligandscis trans-isomeria is impossible.

6. Mirror (optical) isomeria, For example, in the dichloro-diethylenediandiamine-chromium (III) +: +:

As in the case of organic substances, the mirror isomers have the same physical and chemical properties and differ in the asymmetry of crystals, the direction of rotation of the plane of the polarization of light.

7. Isomeria ligands For example, for (NH 2) 2 (CH 2) 4 The following isomers are possible: (NH 2) - (CH 2) 4 -NH 2, CH 3 -NH-CH 2 -CH 2 -NH-CH 3, NH 2 -ch (CH 3) -CH 2 -CH 2 -NH 2

Communication problem in complex compounds.The nature of communication in the COP is different and three approaches are currently used to explain: the Sun method, the MO method and method of the theory of the crystal field.

Method Sun.introduced polne. The main provisions of the method:

1. Communication in the COP is formed as a result of donor-acceptor interaction. Ligands provide electronic pairs, and the complexing agent is free orbitals. Communication strength measure is the degree of overlapping orbital.

2. Hybridization orbitals are subjected to hybridization, the type of hybridization is determined by the number, nature and electronic structure of ligands. Hybridization Co. is determined by the geometry of the complex.

3. Additional hardening of the complex occurs due to the fact that in the S-bond is formed in binding.

4. The magnetic properties of the complex are determined by the number of unpaired electrons.

5. In the formation of the complex, the distribution of electrons in orbitals may remain both in neutral atoms and undergo changes. It depends on the nature of the ligands, its electrostatic field. A spectrochemical range of ligands has been developed. In case ligands have a strong field, they shift electrons, causing them to mate and form a new connection.

Spectrochemical row of ligands:

CN -\u003e NO 2 -\u003e NH 3\u003e CNS -\u003e H 2 O\u003e F -\u003e OH -\u003e CL -\u003e BR -

6. Sun method makes it possible to explain the formation of communication even in neutral and cluster complexes

K 3 K 3

1. The first KS of Ligands create a strong field, the second is weak

2. Draw Valented Orbital Equipment:

3. Consider the donor properties of ligands: CN - have free electronic orbitals and there are donors of electronic pairs.
Posted on Ref.rf
CN - has a strong field, acts on 3Dorbital, sealing them.

As a result, 6 ties are formed, while internal 3 Dorbitali participate in connection, ᴛ.ᴇ. An intrabital complex is formed. The complex is paramagnetic and lowospinov, because There is one unpaired electron. The complex is stable, because Busy internal orbitals.

Ions F - have free electronic orbitals and there are donors of electronic pairs, possess a weak field, in connection with this can not compact electrons on a 3D level.

As a result, a paramagnetic, highly spinning, foreign-bred complex is formed. Low-resistant and reactive.

The advantages of the method of Sun.: Informativeness

Disadvantages of the Sun method: The method is suitable for a determined circle of substances, the method does not explain the optical properties (painting), does not make energy assessment, because In some cases, a quadratic complex is formed instead of a more energetically advantageous tetrahedral.

Comprehensive compounds. - Concept and species. Classification and features of the category "Complex compounds." 2017, 2018.

As you know, the metals have a property lose electrons and, thereby forming. Positively charged metal ions can be surrounded by anions or neutral molecules, forming particles called complex and capable of independent existence in a crystal or solution. And compounds containing complex particles in the nodes of their crystals are called complex compounds.

The structure of complex compounds

1. Most complex compounds have internal and external spheres . Recording chemical formulas for complex compounds, the inner sphere is to enter square brackets. For example, in complex compounds to and CL 2, the inner sphere are groups of atoms (complexes) - - and 2+, and the ions - ions K + and CL - respectively.
2. Central atom or ion The inner sphere is called Complexedomy. Usually, metal ions with a sufficient amount of free - it is P-, D-, F-elements: Cu 2+, Pt 2+, Pt 4+, Ag +, Zn 2+, Al 3+, etc., act as complex consumption. But it may be atoms of elements forming non-metals. The charge of the complex agent is usually positive, but may also be negative or equal to zero and is equal to the sum of charges of all other ions. In the examples above, the complexes are Al 3+ and Ca 2+ ions.

1. The complexing agent is surrounded and is associated with the ions of the opposite sign or neutral molecules, the so-called ligands. As ligands in complex compounds, such anions as F -, OH -, CN -, CNS -, NO 2 -, CO 3 2-, C 2 O 4 2-, and other, or neutral molecules H 2 O, NN 3, CO, NO, etc. In our examples, these are ions OH - and NH 3 molecules. The number of ligands in various complex compounds lies in the range from 2 to 12. And the number of ligands (the number of sigma links) is called the coordination number (K.ch.) of the complexing agent. In the examples of the K.ch. Equally 4 and 8.

1. Charge complex (inner sphere) is defined as the sum of charges of the complexing agent and ligands.
2. Forest sphere Form ions associated with a complex ionic or intermolecular connection and having a charge, the sign of which is opposite the sign of the complex of the complexing agent. The numerical value of the external sphere is coincided with the numerical value of the charge of the internal sphere. In the complex compound formula, they are written in square brackets. The external sphere may be absent at all, if the inner sphere is neutral. In the examples given, the external sphere is formed by 1 ion K + and 2 CL ions - respectively.

Classification of complex compounds

Based on various principles, comprehensive compounds can be classified in various ways:

1. By electrical charge: cationic, anionic and neutral complexes.

• Cationic complexes They have a positive charge and are formed if neutral molecules are coordinated around a positive ion. For example, Cl 3, Cl 2
• Anionic complexs They have a negative charge and are formed if atoms with negative are coordinated around a positive ion. For example, K, K 2
• Neutral complexes they have a charge equal to zero and do not have an external sphere. They may form when coordinating around the atom of molecules, as well as with simultaneous coordination around the central positively charged ion of negative ions and molecules.

1. By the number of complexes

• Single core - the complex contains one central atom, for example, k 2
• Multi-coree. - the complex contains two or more central atoms, for example,

1. By type of liganda

• Hydata - Contain ABO-complexes, i.e. Molecules of water are as ligands. For example, BR 3, BR 2
• Ammonia - contain ammmin-complexes in which ammonia molecules (NN 3) protrude as ligands. For example, Cl 2, Cl
• Carbonyls - In such complex compounds, carbon monoxide molecules are performed as ligands. For example, , .
• Acidomplexes - complex compounds containing acid residues as oxygen-containing and oxygen acids (F -, CL -, BR -, I -, CN -, NO 2-, SO 4 2-, PO 4 3-, etc., And also he -). For example, K 4, Na 2
• Hydroxocomplexes - Complex compounds in which hydroxide ions are as ligands: K 2, CS 2

Complex compounds may contain ligands relating to various classes of the classification. For example: K, BR

1. By chemical properties: Acids, bases, salts, non-electrolytes:

• Acid - H, H 2
• Basis - (OH) 2, OH
• Sololi. — CS 3, CL 2
• Neelectrics —

1. By the number of places occupied by the ligand in the coordination sphere

In the coordination sphere of ligands can take one or more places, i.e. To form one or more connections with a central atom. This feature distinguish:

• Monodentate ligands - these are such ligands as H 2 O, NH 3, CO, NO, and others molecules and other CN -, F -, CL -, OH -, SCN -, etc.
• Bidentate ligands . Such type of ligands include ions H 2 N-CH 2 -COO -, CO 3 2-, SO 4 2-, S 2 O 3 2-, ethylenediamine molecule H 2 N-CH 2 -CH 2 -H 2 N (abbreviated en).
• Polydentate ligands . This, for example, organic ligands containing several groups - CN or -COOH (EDTA). Some polydentantic ligands are capable of forming cyclic complexes, called chelate (for example, hemoglobin, chlorophyll, etc.)

Nomenclature of complex compounds

To record complex compound formula It must be remembered that, like any ionic compound, the formula of the cation is initially recorded, and after - the anion formula. At the same time, the formula of the complex is recorded in square bracketswhere the complexing agent first is recorded, then ligands.

But several rules following which the name of the compound compound will not be difficult:

1. In the names of complex compounds, like ion salts, the first indicate anion, and then the cation.
2. In the title of the complex at first, ligands indicate, and after - the complex. Ligands are listed in alphabetical order.
3. Neutral ligands are also called moleculesThe ending is added to the anion ligands -about. The table below shows the names of the most common ligands.

1. If the number of ligands is greater than the unit, then their number indicate the Greek prefixes:

2-di-, 3-tri-, 4-tetra-, 5-penta-, 6-hexa-, 7-hepta-, 8-octa-, 9-non-10-deca-.

If the Greek prefix is \u200b\u200balready present in the title of the ligand itself, the name of the ligand is written in brackets and the prefix type is added to it:

2-bis-, 3-tris-, 4-tetrakis-, 5-pentakis-, 6-hexakis-.

For example, CL 3 compound is called Tris (ethylenediamine) cobalt (III).

1. The names of complex anions ends suffix - aT.
2. After the name of the metal In brackets indicate roman numbers of its oxidation.

For example, let's call the following compounds:

• Cl.

Let's start from ligands: 4 water molecules are indicated as tetraakva, and 2 chloride ion - as dichloro.

Finally, anion in this compound is an chloride ion.

tetraakvadichlorochromh chloride (III)

• K 4.

Let's start with ligands: The complex anion contains 4 ligand Cn - called Tetracyano.

Since the metal is included in the complex anion, it is called nickelt (0).

So, the full name is such - tetracyanonikelates (0) Potassium