| Abstract: | Synthesis and Structures of Vanadium(III) and Vanadium(IV) Silanolates The syntheses of the new and partially known vanadium(III)-silanolate complexes {V(OSiMet2Bu)3}2(THF)] ( 1 ), Li(THF)2V(OSiMet2Bu)4] ( 2 ), V(OSiMet2Bu)(lut)] ( 3 ), V(OSiPh3)3(THF)3 ( 4 ), Li(THF)4]V(OSiPh3)4](THF)2 ( 5 ), Li(DME)VMes(OSiMet2Bu)3] ( 7 ), Li(THF)4]VMes · (OSiPh3)3] ( 8 ), Li(THF)4]VMes3(OSiMet2Bu)] ( 9 ), and NaVMes3(OSiPh3)](THF)4 ( 10 ) as well as the vanadium(IV) compounds V(OSiPh3)4] ( 6 ), VMes3(OSiMet2Bu)] ( 11 ) and VMes3(OSiPh3)] ( 12 ) are reported. In most cases the vanadium atom displays a coordination number of four. The dimeric structure of 1 with coordination numbers of four and five, respectively, has been deduced from molecular mass measurements, mass spectrometry and its magnetic properties. The crystal structures of compounds 2 , 4 , 5 , 9 and 11 were resolved. Complex 2 resembles a bridged contact ion pair in which both metal centres are in a tetrahedral coordination environment. In 4 the ligands are arranged trigonal bipyramidally with the THF molecules in the axial positions. Complexes 5 and 9 crystallize in separated ion paires with the vanadium in a tetrahedral coordination sphere. The crystal structure of 11 is analogous to that of 9 but with consequences due to the higher oxidation state. Oxidation of the vanadates(III), e. g. 5 , 9 and 10 , yields the corresponding vanadium(IV) compounds 6 , 11 and 12 . |
