Germanium compounds transition-metal complexes

Anionic Rearrangement of Organosilicon and Germanium Compounds, 16, I Application of, 3C-NMR Spectroscopy to Organo-Transition Metal Complexes, 19, 257 Applications of """Sn Mdssbauer Spectroscopy to the Study of Oiganotin Compounds, 9, 21... 

Transition metal complexes of germanium, tin and lead TABLE 13. Selected mononuclear transition metal-lead compounds... 

The chemistry of silicon, germanium, and tin transition metal compounds has been the subject of several reviews (12, 180). Optically active silyl ligands have been introduced in a transition metal complex by reaction of chiral functional organosilanes. However chiral silyl ligands containing complexes are limited to a few metal centers we shall discuss in turn iron, cobalt, platinum, and manganese complexes. 

The isolation of transition metal complexes with the triple bonds to an almost linearly coordinated germanium atom and the isolation of R-M-X species (M = Ge, Sn, Pb, X = Cl, 53-56,69,70,141,142 vhich should be good precursors for triple bonds, suggested that stable compounds of the general formula RM=MR (M = Si, Ge, Sn, Pb) are synthesizable and isolable target molecules. 

The yellow germanium (m.p. 18() C) and brick-red tin complexes (m.p. 1 36 C) are thermally stable but air-sensitive solids which can be sublimed in vacuo, but the purple lead analogue is rather heat and photosensitive. They are monomeric in the vapour and in their solutions in benzene. X-ray diffraction of the tin compound shows that it dimerizes in the solid state. The monomer has both a lone pair and vacant p orbital. It acts as a Lewis base towards transition metal complexes and as a Lewis acid towards pyridine. Dimerization may therefore occur through mutual acid-base interaction to form a bent tin—tin double bond. 

The single-bond compounds between Si, Ge, and Sn and chalcogens (S, Se, Te) are reactive and used as synthetic intermediates in the synthesis of organic compounds, organochalcogen compounds, organo-silicon, -germanium and -tin compounds, and transition metal-chalcogen complexes and clusters. 

Silicon and germanium hydrides react with cobalt, manganese and rhenium carbonyls affording complexes having a silicon (or germanium)-metal bond. These reactions, described previously for inactive compounds have been used in the synthesis of optically active silyl and germyl-transition metals ... 

In a third class of 7t-cyclopentadienyl complexes, compounds of type LVIII are bound to a transition metal via the lone pair at the germanium atom. The first compounds in this series, the pentacarbonyl-[chloro(pentamethylcyclopentadienyl)germylene]chromium(0) (LIXa) and -tungsten(O) (LIXb) were synthesized by alkylation of the ylide complexes (CO)5M—GeCl2 THF according to Eq. (22) (201). Nucleophilic substitution reactions of LIXb lead to the alkyl- and amino-substituted complexes LIXc-e [Eq. (23)] (202). 

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