🗊Презентация Complex compounds

COMPLEX COMPOUNDS

compounds, which include complex ions, existing in the crystal, and in solution, called the complex or coordination compounds compounds, which include complex ions, existing in the crystal, and in solution, called the complex or coordination compounds

Structure of complex compounds In a molecule of a complex compound, one of the atoms, generally positively charged, occupies the central site (central ion or complexing agent).

Oppositely charged ions or neutral molecules called ligands are coordinated around the central ion. Oppositely charged ions or neutral molecules called ligands are coordinated around the central ion.

The complexing agent and ligands form inner sphere of a complex compound. It is characterized by coordinate bonds which are formed while overlapping of empty p- and d-orbitals of a central ion and orbitals containing lone electron pairs of ligands. The ions in the outer sphere are mainly bonded to the complex ions by forces of electrostatic interaction (ionic bonds). The complexing agent and ligands form inner sphere of a complex compound. It is characterized by coordinate bonds which are formed while overlapping of empty p- and d-orbitals of a central ion and orbitals containing lone electron pairs of ligands. The ions in the outer sphere are mainly bonded to the complex ions by forces of electrostatic interaction (ionic bonds).

The total number of coordinate bonds formed by the complexing agent is known as coordination number of the central ion. It mainly depends upon the charge of the complexing agent (for monocharged ions it usually equals 1, for discharged ions – 4 or 6, for tricharged – 6 and above), and the size of an ion (the larger the central ion, the greater its coordination number is, for lanthanides and actinides it can reach to 12). The total number of coordinate bonds formed by the complexing agent is known as coordination number of the central ion. It mainly depends upon the charge of the complexing agent (for monocharged ions it usually equals 1, for discharged ions – 4 or 6, for tricharged – 6 and above), and the size of an ion (the larger the central ion, the greater its coordination number is, for lanthanides and actinides it can reach to 12).

Nomenclature of complex compounds Names of complex compounds are similar to the names of simple salts. The order of naiming particles in a complex ion is the following: anionic ligands – neutral ligands – central ion. Number of ligands is designated with the help of greek numerals

[Cu(NH3)4]Cl2 – tetraammine copper(II) chloride; [Cu(NH3)4]Cl2 – tetraammine copper(II) chloride; K2 [Cu(OH)4] – potassium tetrahydroxocupprate(II); [Cr(NH3)3Cl3] – trichloro triammine chromium(III).

Classification of complex compounds There are several types of classification of complex compounds.

Classification of complex compounds 1. Depending upon a charge of the inner sphere: (i) Cationic complexes (the inner sphere is positively charged – complex cations). Examples: [Cr(H2O)6]Cl3, [Co(NH3)6]Cl3. (ii) Anionic complexes (the inner sphere is negatively charged – complex anions). Examples: K2[HgI4], Na[Sb(OH)6]. (iii) Neutral complexes (the inner sphere is not charged). Examples: [Pt(NH3)2Cl2], [Fe(CO)5].

22) Depending upon the type of the ligand: 22) Depending upon the type of the ligand: (i) Aqua-complexes (ligands are water molecules – [Cu(H2O)5]SO4). (ii) Ammino-complexes (ligands are molecules of ammonia or organic ammines – [Ag(NH3)2]Cl). (iii) Hydroxy-complexes (ligands are OH– anions – Na2[Sn(OH)4]). (iv) Carbonyl-complexes (ligands are molecules of carbon monoxide – [Fe(CO)5]). (v) Acido-complexes (ligands are anions of inorganic acids). Examples: chlorocomplexes K2[HgCl4], fluorocomplexes K3[FeF6], cyanocomplexes KFe[Fe(CN)6], thiocyanocomplexes K3[Fe(SCN)6], sulphitocomplexes K[Ag(SO3)], etc.

б)Гидроксокомплексы – это комплексные анионы, в которых лигандами являются гидроксид-ионы OH–. Комплексообразователями являются металлы, склонные к проявлению амфотерных свойств – Be, Zn, Al, Cr. б)Гидроксокомплексы – это комплексные анионы, в которых лигандами являются гидроксид-ионы OH–. Комплексообразователями являются металлы, склонные к проявлению амфотерных свойств – Be, Zn, Al, Cr. Например: Na[Al(OH)4], Ba[Zn(OH)4]. в) Аммиакаты – это комплексные катионы, в которых лигандами являются молекулы NH3. Комплексообразователями являются d-элементы. Например: [Cu(NH3)4]SO4, [Ag(NH3)2]Cl.

Depending upon the nature of a central ion: complexes of copper, silver, iron, chrome etc. Depending upon the nature of a central ion: complexes of copper, silver, iron, chrome etc.

Isomerism

Electronic structure of complex ions Interaction of lone electronic pairs of ligands with empty valence orbitals of the central ion of different types leads to their hybridization. For example, the electronic structure of a complex ion [Cu(NH3)4]2+ can be reflected as following:

Возможны октаэдрические комплексы: Возможны октаэдрические комплексы: внутриорбитальные (d2sp3); внешнеорбитальные (sp3d2);

Электронное строения атома кобальта: Электронное строения атома кобальта: При образовании иона Со3+ освобождается 4s-орбиталь, а на 3d-орбитали остается 6 валентных электронов: Со3+

Entering of lone electronic pairs of ligands into valence orbitals of the central ion leads to their interaction with the electrons of 3d-orbitals. This interaction is defined by degree of penetration of electrons of ligands on empty orbitals of metallic cations. In connection of force of interaction, ligands may be arranged in a spectrochemical series and are devided into ligands of weak and strong field: Entering of lone electronic pairs of ligands into valence orbitals of the central ion leads to their interaction with the electrons of 3d-orbitals. This interaction is defined by degree of penetration of electrons of ligands on empty orbitals of metallic cations. In connection of force of interaction, ligands may be arranged in a spectrochemical series and are devided into ligands of weak and strong field:

Все валентные электроны спарены. Комплекс [Co(NH3)6]3+ - диамагнитный, что согласуется с экспериментом.

2. Если лиганды недостаточно активны и спаривания электронов на внутренних d-орбиталях не происходит, то в гибридизации участвуют внешние d-орбитали (sp3d2): 2. Если лиганды недостаточно активны и спаривания электронов на внутренних d-орбиталях не происходит, то в гибридизации участвуют внешние d-орбитали (sp3d2): F– - создает слабое поле Четыре электрона иона кобальта неспарены, комплекс - парамагнитен.