Tertiary stibines structure

From a structural point of view the complexes with tertiary stibine ligands are very uniform. The predominant type is rj coordination (type 1), with electron pair donation of the Sb atom to the metal centre.1,2,6,8 However, complexes with bridging stibine ligands (type 2) are also known.13,14 (Scheme 1). 

Related to tertiary stibines is the (Me3Si)3Sb ligand. Recent studies of this ligand comprise coordination on transition metal and main group element centers. An example for a transition metal complex with a known crystal structure is [(CO)5CrSb(SiMe3)3],5° the structure of which is depicted in Fig. 2. 

Considerable structural information is available on osmium complexes of tertiary phosphines, arsines and stibines (Table 1.13) [152, 157]. 

Considerable structural information is available on osmium complexes of tertiary phosphines, arsines and stibines (Table 1.13) [152, 157], Comparison with data (mainly obtained from EXAFS measurements) on osmium diarsine complexes (Table 1.14) shows that as the oxidation state increases, osmium-halogen bonds shorten whereas Os-P and Os-As bonds lengthen. Bond shortening is predicted for bonds with ionic character,... 

Apart from the triethylarsine972 and the tribenzylarsine974 complexes the remaining tertiary arsine complex is formed by the ditertiary arsine l,2-(Ph2As)2C2H4 clearly this cannot adopt structure (80). However, the ditertiary stibine complexes976 may well adopt structure (80), since their stoichiometry implies that only half the antimony atoms are coordinated to rhodium. 

Tertiary arsines, phosphines, and stibines can also be displaced from their CuX(ZPh3)3 or Cu2X2(Z Ph3)3 (Z = As, P Z = As, P, Sb X = halogen) complexes by pyridine and related amines to give CuX(ZPh3)(amine) complexes. The structures of these are uncertain since their dissociation or decomposition in solution makes molecular weight data unreliable (176, 178). 

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