Group IVA ligands

PLATINUM COMPLEXES OF GROUP IVA LIGANDS 52.4.1 Monomeric Platinum(II) Cyanide Complexes... 

Group IVA Donor Ligands. The anomalous reactions of PhaSiCl with metal carbonyl anions are discussed on p. 180. Only in the case of [Co(CO)3PPh3] was the normal substitution product obtained. GeH3Br reacts with Na-[Co(CO)4] in ether to produce [H3GeCo(CO)4]. The trideuterio-compound has also been prepared and spectroscopic properties reported for both compounds. The preparation and attempted preparation of halogen-bridged Ge-M compounds is referred to on pp. 180 and 200. In the case of cobalt. 

Indeed, the majority of the higher-covalent silicon compounds studied which have an increased coordination number are formed by bi-, tri-, and tetradentate ligands similar effects are apparent with other Group IVA elements. It is likely that the structural factors are responsible for the existence of pentacoordinate pentavalence carbon species expanding the valence shell to 10 (Sect. 3.2). For the same reason that there are about twenty structures of the organotin complexes with seven- and eight-coordination... 

Diene and polyene complexes with t) -coordination are known for nearly all the transition metals from group IVA to VIII. Table I offers examples for Cr—Rh. Ligand... 

The position of silicon directly below carbon in the periodic table suggests that the chemistry of these elements will be similar. Like carbon, silicon has a valency of four. SiUcon(n) is not stable, however, and the tendency to form divalent compounds increases with atomic weight so that compounds of the form SnL2 and PbL (where L is used to denote an arbitrary ligand) are relatively common. The Group IVA elements, other than carbon, do not form strong bonds with like atoms. The Si—Si bond, for example, is notably weaker (222kJ/mole) than the Si—C bond (328 kj/ mole) (Table 1). 

Lappert, M. F., Heavy Atom Main Group IVA Analogs of Carbenes, Radicals, and Alkenes. The Use of Bulky Trimethylsilyl-Substituted Ligands, Silicon, Germanium, Tin Lead Comp. 9 [1986] 129/54. 

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