Dehydrohalogenation by a Germylene: Conversion of Carbene Ligands into Carbynes at Ruthenium

The dialkylgermylene [Ge(CH[SiMe3]2)2] (3)
converts the carbene complexes [Ru(CHR)(PCy3)2Cl2] (R
= p-C6H4Me [2], n-C4H9 [6]) into the corresponding
square-planar carbyne complexes [Ru(CR)(PCy3)2Cl] (R
= p-C6H4Me [1], n-C4H9 [7]) cleanly within minutes at
25 °C in benzene; addition of HCl to a benzene solution
of 1 results in quantitative re-formation of 2. Replacement of chloride in 1 affords other halide and pseudohalide complexes, [Ru(C-p-C6H4Me)(PCy3)2X] (X = p-OC6H4-t-Bu, Br, F, O3SCF3), cleanly.