Diruthenium Carbido Complexes as<i>N</i>-Heterocyclic Carbene Like C-Donor Ligands to Group 11 Metals

Abstract

Deprotonation of the diruthenium μ-methylidyne complex [(Cp*Ru) 2 (μ-N t Bu)(μ-CH)][BF 4 ] (Cp* = η 5 -C 5 Me 5 ) with 2 equiv of KN(SiMe 3 ) 2 in the presence of CuCN, AgOTf, or AuCl(SMe 2 ) afforded the trigonal planar bridging carbido complexes [(Cp*Ru) 2 (μ-N t Bu)(μ 3 -C)M{N(SiMe 3 ) 2 }] (M = Cu ( 4 ), Ag ( 5 ), and Au ( 6 )). Complexes 4 and 6 were characterized crystallographically. The M–C bonding in these complexes showed considerable similarity with that in the N -heterocyclic carbene (NHC) derivatives (NHC)M{N(SiMe 3 ) 2 } (M = Cu and Au), illustrating the analogy between the diruthenium carbido ligand [(Cp*Ru) 2 (μ-N t Bu)(μ-C)] and NHCs. The reaction of 4 with 2,6-di- tert -butylphenol allowed derivatization via protonolytic exchange of the disilazide moiety, yielding the aryloxo complex [(Cp*Ru) 2 (μ-N t Bu)(μ 3 -C)Cu(OAr)] ( 7; Ar = 2,6- t Bu 2 C 6 H 3 ), which was also structurally characterized. The electron donor ability and steric bulkiness of the diruthenium carbido ligand were studied by computational methods.