Bonding in complexes

The word ligand to describe an atom, or group of atoms, attached to a central metal atom can also be confusing. This has arisen because the type of bonding in complexes tends to be different from that in, say, H2O. However, the difference is quantitative rather than... 

Until about 20 years ago, the valence bond model discussed in Chapter 7 was widely used to explain electronic structure and bonding in complex ions. It assumed that lone pairs of electrons were contributed by ligands to form covalent bonds with metal atoms. This model had two major deficiencies. It could not easily explain the magnetic properties of complex ions. 

C.K. J0rgensen, Absorption Spectra and Chemical Bonding in Complexes, Perga-mon Press, Oxford, 1962. 

C. K. Jorgensen, Absorption Spectra and Chemicai Bonding in Complexes, Addison-Wesley, Reading, Mass., 1962. 

Jorgensen CK (1962) Absorption spectra and chemical bonding in complexes, Pergamon Oxford... 

In a first part, experimental methods for studying formation, properties, structures and bonding in complex compounds of cadmium and mercury are briefly surveyed, usually with hints to reviews of the respective field and to examples of recent applications. 

STRUCTURES AND BONDING IN COMPLEX COMPOUNDS OF CADMIUM AND MERCURY... 

Fig. 7. Electronic absorption spectra, d—d region, of Pt(II)Cl and Pt(IV)Cl in aqueous solution (from Jorgensen, C. K.. Absorption Spectra and Chemical Bonding in Complexes. London Pergamon 1962)...

Only two unpaired electrons are present in this complex, and as will be shown in the next section, the two types of manganese complexes can be distinguished by means of their magnetic character. We have not explained why electron pairing occurs with some ligands but not others. The discussion of this aspect of bonding in complexes will be treated fully in Chapter 17. 

A number of systems have been studied where a formal ligand displacement reaction is followed by an isomerization process. One recently described example involves the cleavage of a Pt-C(alkyl) cr-bond in complexes of the type cis-[Pt(R)(R )(PEt3)2] to produce cis-[Pt(R)(PEt3)2(MeOH)]+ and R H, which subsequently isomerizes to nms-[Pt(R)(PEt3)2(MeOH)]+ (90). The first protonolysis reaction is characterized by significantly negative volumes of activation between... 

Table 28. H-bonding in complexes IlgCO-HOK. Calculations with minimal basis sets...

Finally, a word of caution should be offered against making a straightforward comparison of the M-Si bonds in complexes of different metals, since this parameter is strongly affected by the size of the metal. The latter tends to decrease from left to right in a given row of the Periodic Table due to the d-contraction, but increases down the Group (particularly between the first and second transition series). 

Fig. 13. Possible theoretical descriptions of the bonding in complexes [M(H)3(SiR3)L3].

Bond Lengths for S—S Bonds in Complexes with Bidentate Ligands - ... 

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