Synthesis and Rearrangements of Tungsten Germyl Silyl Complexes

Germyl silyl complexes Cp 2 W(SiMe 3 )(GeR 3 ) have been synthesized by the reaction of the tungsten silene complex Cp 2 W(η 2 -Me 2 Si CH 2 ) with germanes HGeR 3 (GeR 3 = GeMe 3 ( 2 ), GeMe 2 H ( 3a ), Ge t Bu 2 H ( 3b ), GePh 2 H ( 3c )). Chlorogermyl derivatives are synthesized by the reaction of 3a-c with CCl 4 to yield Cp 2 W(SiMe 3 )(GeMe 2 Cl) ( 4a ), Cp 2 W(SiMe 3 )(Ge t Bu 2 Cl) ( 4b ), and Cp 2 W(SiMe 3 )(GePh 2 Cl) ( 4c ). Complex 4a has been structurally characterized by a single-crystal X-ray diffraction study. The corresponding triflate derivative, Cp 2 W(SiMe 3 )(GeMe 2 OTf) ( 5a ), has been prepared by the reaction of 4a and trimethylsilyl triflate. Substitution of triflate for chloride in Cp 2 W(SiMe 3 )(Ge t Bu 2 Cl) ( 4b ) requires mild heating (80 °C) and is accompanied by concurrent redistribution of groups between silyl and germyl centers to yield the silyl triflate Cp 2 W(SiMe 2 OTf)(Ge t Bu 2 Me) ( 6b ). Under thermolytic conditions, germyl silyl complexes undergo intra- and intermolecular redistribution of substituents between the germyl and silyl ligands. This process is proposed to occur via a cationic germylene complex formed by triflate or chloride dissociation.