Mixed Bis(μ-silylene) and (μ-Silylene)/(μ-Germylene) Complexes Involving the Rh/Ir Metal Combination: Nature of the Si···Si Interactions in the Bis(μ-silylene) Species

A series of mixed bis­(μ-silylene) complexes of
rhodium and
iridium [RhIr­(CO)2(μ-SiHR)­(μ-SiR1R2)­(dppm)2] (R = R1 = R2 = Ph (4); R = R1 = Ph, R2 = Cl
(5); R = R1 = Ph, R2 = Me (6); R = 3,5-C6H3F2, R1 = Ph, R2 = Me (7); R = 3,5-C6H3F2, R1 = 2,4,6-C6H2Me3, R2 = H (8))
have been synthesized by the reaction of the silylene-bridged dihydride
complexes, [RhIr­(H)2(CO)2(μ-SiHR)­(dppm)2] (1, R = Ph; 2, R = C6H3F2), with a number of secondary or primary
silanes (Ph2SiH2, PhClSiH2, PhMeSiH2, C6H2Me3SiH3).
The influence of substituents and π-stacking interactions on
the Si···Si distance (determined by X-ray crystallography)
in this series and the implications regarding the nature of the Si···Si
interactions are discussed. A series of novel (μ-silylene)/(μ-germylene) complexes, [RhIr­(CO)2(μ-SiHPh)­(μ-GePh2)­(dppm)2] (9) and [RhIr­(CO)2(μ-SiR1R2)­(μ-GeHPh)­(dppm)2] (R1 = Ph, R2 = H (11); R1 = R2 = Ph (12); R1 = Ph,
R2 = Me (13)), have also been synthesized
by reaction of the silylene-bridged dihydride complex, [RhIr­(H)2(CO)2(μ-SiHPh)­(dppm)2] (1), with 1 equiv of diphenylgermane and by reaction of the
germylene-bridged dihydride complex, [RhIr­(H)2(CO)2(μ-GeHPh)­(dppm)2] (3), with
1 equiv of the respective silanes. These complexes have been characterized
by multinuclear NMR spectroscopy and X-ray crystallography.