Coordination Chemistry of [E(Idipp)]2+Ligands (E = Ge, Sn): Metal Germylidyne [Cp*(CO)2W≡Ge(Idipp)]+and Metallotetrylene [Cp*(CO)3W–E(Idipp)]+Cations

The synthesis and full characterization of the NHC-stabilized tungstenochlorostannylene [Cp*(CO) 3 W–SnCl(Idipp)] ( 1Sn ), the NHC-stabilized chlorogermylidyne complex [Cp*(CO) 2 W═GeCl(Idipp)] ( 2 ), the tungsten germylidyne complex salt [Cp*(CO) 2 W≡Ge(Idipp)][B(C 6 H 3 -3,5-(CF 3 ) 2 ) 4 ] ( 3 ), and the cationic metallostannylene [Cp*(CO) 3 W–Sn(Idipp)][Al(OC(CF 3 ) 3 ) 4 ] ( 4Sn ) are reported (Idipp = 2,3-dihydro-1,3-bis(2,6-diisopropylphenyl)-1 H -imidazol-2-ylidene, Cp* = η 5 -C 5 Me 5 ). Metathetical exchange of SnCl 2 (Idipp) with Li[Cp*W(CO) 3 ] afforded selectively 1Sn . Photolytic decarbonylation of the Ge analogue [Cp*(CO) 3 W–GeCl(Idipp)] ( 1Ge ) afforded the NHC-stabilized chlorogermylidyne complex ( 2 ), featuring a trigonal-planar coordinated germanium center and a W–Ge double bond (W–Ge 2.3496(5) Å). Chloride abstraction from 2 with Na[B(C 6 H 3 -3,5-(CF 3 ) 2 ) 4 ] yielded the germylidyne complex salt 3, which contains an almost linear W–Ge–C1 linkage (angle at Ge = 168.7(1)°) and a W–Ge triple bond (2.2813(4) Å). Chloride elimination from 1Ge afforded the tungstenogermylene salt [Cp*(CO) 3 W–Ge(Idipp)][B(C 6 H 3 -3,5-(CF 3 ) 2 ) 4 ] ( 4Ge ), which in contrast to 1Ge could not be decarbonylated to form 3 despite the less strongly bound carbonyl ligands. The tin compounds 1Sn and 4Sn did not afford products bearing multiple W–Sn bonds. Treatment of 4Ge with Me 2 NC≡CNMe 2 yielded unexpectedly the neutral germyl complex 5 containing a pendant 1-germabicyclo-[3,2,0]-hepta-2,5-diene ligand instead of the anticipated [2 + 1]-cycloaddition product at the Ge-center.