Syntheses and structures of some complexes containing M3(μ-dppm)3 moieties (M = Cu, Ag) linking C4{M′Lx} groups [M′Lx = Re(CO)3(But2-bpy), Ru(dppe)Cp∗]

Reactions between [Ru(CCCCH)(dppe)Cp∗] and [M2(NCMe)x(dppm)2]2+ (M=Cu, x=4; Ag, x=2) have given complexes containing M3(μ-dppm)3 clusters attached to one or two CCCC[Ru(dppe)Cp∗] groups. Single crystal X-ray studies are recorded for [{M3(μ-dppm)3}{μ3-CCCC[Ru(dppe)Cp∗]}](BF4)2·nS (M=Cu, Ag) [isomorphous (orthorhombic) for S=(ill-defined) acetone]. A different (triclinic) polymorph has also been defined for M=Ag, nS=5THF. Together with [{Cu3(μ-dppm)3}{μ3-CCCC[Ru(dppe)Cp∗]}2]PF6·4Me2CO, the structures definitively confirm the complexes as clear examples of mono- or bis-diyndiyl-M3 systems, devoid of close approaches to the vacant M3 faces of the former by counterions in the case of their acetone solvates, except in the case of the BF4 counterion in the AgBF4/thf solvate. Cyclic voltammetric studies suggest that there are only weak electronic interactions between the ruthenium centres in the bis(diynyl) complexes, consequent upon weak overlaps between the carbon chain and the M3(μ-dppm)3 clusters, as confirmed by DFT calculations on model complexes [{M3(μ-dHpm)3}{CCCC[Ru(dHpe)Cp]}n]3-n [n=1, 2; dHpm=CH2(PH2)2, dHpe=H2P(CH2)2PH2]. The complexes [Ag3Cl2(dppm)3]PF6, [M3(μ-dppm)3(X){μ3-CCCC[Re(CO)3(But2-bpy)]}]PF6 (M=Cu, X=CCCC[Re(CO)3(But2-bpy)]; M=Ag; X=Cl), [Ag6(μ-dppm)4{CCCC[Re(CO)3(But2-bpy)]}4](PF6)2 have also been prepared and structurally characterised. In the M3 clusters, some asymmetry in the attachment of at least one of the μ3 ligands is apparent, which results from interactions with solvate molecules.