Transition metal germylene complexes

Stable mononuclear transition-metal germylene complexes with a formal triple bond between the Ge and metal atoms (Cr, Mo, W, 56-62) have been synthesized by a combination of salt-elimination and decarbonylation reaction (equation 44)150,151. The decarbonylation process for the Cr and W intermediates 61 and 62 can involve either a thermal or a photochemical reaction the molybdenum germylyne complexes 56 and 57 were obtained directly, even at low temperatures. 

TABLE 9. X-ray structural data of transition metal germylene complexes... 

Over the past decade, several more transition metal germylene complexes with ix coordination have been synthesized and characterized by X-ray crystallography for... 

The early development of transition-metal germylene chemistry is summarized in earlier reviews4b-d. Therefore we summarize the transition-metal germylene chemistry developed after 1990. Such complexes can be divided into seven different types (I-VII) depending upon the nature of bonding between the metal and germanium atom ... 

Germylenes can be released thermally in the presence of a transition metal complex leading to the formation of a germanium-metal bond (Equation (193)).239 The reaction occurs at room temperature when a germylsilane is used as the synthon (Equation (194)).240... 

Like silylenes and carbenes germylenes are isolobal with phosphines and may function as ligands to transition metal complexes. (Adapted from Bazlnet et ah, 2001)... 

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). 

C. Synthesis of Transition Metal Germanium Double Bond Germylene Complexes... 

TABLE 4. Transition metal complexes with bridging germylene ligands... 

This method has been more widely used for the synthesis of bridged germylene complexes than for their silicon analogs. The reactions of transition-metal carbonyl monoanions with Me2GeCl2 give A-type bridged... 

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