Complexes of Germanium

Germanocenes LVIIa-j, Interplane Angles (a), and Average Ge—C Distances (a) 

These germylene complexes are light yellow to orange, rather air sensitive but thermostable, crystalline compounds, easily soluble in aprotic polar and nonpolar solvents. According to X-ray investigations, gas phase electron diffraction studies, and molecular weight determinations, the complexes are monomeric species in the solid and gaseous state and also in solution. An 

Calculated Orbital Energies (—e), Vertical Ionization Energies (/ ,), and Their Assignments for HsC5GeCl and Me5C5GeCl 

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). 

GeCI + GeClj-dioxane i-ox— Me5C5Ge]+ GeCI3 (LXe) (26) 

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Meanwhile, Parkin and his co-workers have also reportedthe synthesis of a series of terminal chalcogenido complexes of germanium 66, 67, and 68 (Scheme 20).42 X-ray structural analyses of 66, 67, and 68 revealed that they have unique germa-chalcogenourea structures stabilized by the intramolecular coordination of nitrogen atoms. The central Ge-X (X = S, Se, Te) bond of 66, 67, and 68 should be represented by a resonance structure, Ge+ - X- —>- Ge=X, because their bond... 

There are some examples of macrocyclic complexes of germanium, tin and lead reported in the recent literature. Several crown ethers73,75, tetraaza macrocycles76 [for instance dibenzotetramethyltetraaza[14]annulene (TMTAA)], cyclic polyamines (polyazacycloalkanes)77-80 or, as already mentioned above, poly(pyrazolyl)borate were... 

TABLE 12. Reduction potentials of porphyrin-iron carbonyl complexes of germanium and tin in CH2CI2 with TBA(PF<5), 0.1 M, on Au electrodes vs SCEa... 

Reaction of germylenes with elemental chalcogens (sulfur, selenium, tellurium) also allowed the synthesis of stable >Ge = E species. This was first exemplified by the isolation of terminal chalcogenido complexes of germanium 170152 and 171-173153 (Scheme 34). Stabilization in these cases is achieved by intramolecular complexation of the metal atom by Lewis bases. 

TABLE 84. Selected bond distances and angles for phyrazine complexes of germanium and tin some porphyrin, phthalocyanine and por-... 

Transition metal complexes of germanium, tin and lead I. ABBREVIATIONS... 

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