Transition-metal-substituted polysilanes

Pannell et al. Transition-Metal-Substituted Oligo- and Polysilanes 331... 

Harrod-type catalytic dehydrocoupling method using early transition metal catalysts (see COMC II (1995), chapter Organopolysilanes, p 99, and earlier in this review, Section 3.11.4.1.3. (i)).69,75 Si-H bonds are susceptible to free radical attack, and use of this was made in the free radical substitution of 38 to prepare a number of oxy-functionalized polysilanes, as shown in Scheme 25.185,186... 

Soluble and well-characterized polygermane homopolymers, (R Ge), and their copolymers with polysilanes have been prepared by the alkali metal coupling of diorgano-substituted dihalogermanes (137—139), via electrochemical methods (140), and by transition-metal catalyzed routes (105), as with the synthesis of polysilanes. 

In the last years transition metal-silyl complexes have received special attention for several reasons [1, 2], On the one hand, they are assumed to be important intermediates in catalytic processes [2] (transition metal-catalyzed hydrosilylation reaction, dehydrogenative coupling of silanes to polysilanes, etc.), on the other metal-substituted silanes show special properties, which can be tuned systematically by judicious choice of the metal and its ligands [3] Furthermore, silylenes (silanediyls) are stabilized by unsaturated transition metal fragments leading to metal-silicon double-bonds [4]. In the light of a possible application in MOCVD processes some of these complexes are of interest as potential single-source precursors for the manufacture of thin silicide films [5]. 

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