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)3W–SnCl­(Idipp)] (1Sn), the NHC-stabilized chloro­germylidyne complex [Cp*­(CO)2WGeCl­(Idipp)] (2), the tungsten germylidyne complex salt [Cp*­(CO)2WGe­(Idipp)]­[B­(C6H3-3,5-(CF3)2)4] (3), and the cationic metallo­stannylene [Cp*­(CO)3W–Sn­(Idipp)]­[Al­(OC­(CF3)3)4] (4Sn) are reported (Idipp = 2,3-dihydro-1,3-bis­(2,6-diisopropylphenyl)-1H-imidazol-2-ylidene, Cp* = η 5-C5Me5). Metathetical exchange of SnCl2(Idipp) with Li­[Cp*W­(CO)3] afforded selectively 1Sn. Photolytic decarbonylation of the Ge analogue [Cp*­(CO)3W–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(C6H3-3,5-(CF3)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)3W–Ge­(Idipp)]­[B­(C6H3-3,5-(CF3)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 Me2NCCNMe2 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.