Ligand substitution and growth reactions with Ru3Se2 nido clusters. Coordination isomerism in [WRu3(μ4-Se)2(μ-CO)4(CO)7(L)] (L = phosphine ligand) and electrochemical behaviour of the Ru3MSe2 core clusters (M = Ru, W) in solution

The monosubstituted selenido-carbonyl open-triangular nido cluster [Ru3(μ3-Se)2(CO)8(L)] (L = trispyrrolidinylphosphine, tpnp) reacts with trisparamethoxyphenylphosphine (t4mpp) and α,α′-bis(diphenylphosphinemethyl)benzene (dpmb), giving, respectively, the di- and tri-substituted [Ru3(μ3-Se)2(CO)6(tpnp)(dpmb)] and [Ru3(μ3-Se)2(CO)7(tpnp)(t4mpp)] clusters. Moreover, clusters [Ru3(μ3-Se)2(CO)8(L)] (L = tpnp, t4mpp, diphenylmethoxyphosphine (dpxp)) show a reactivity towards [W(CO)3(MeCN)3], leading to the corresponding bimetallic closo clusters [WRu3(μ4-Se)2(μ-CO)4(CO)7(L)]. The formation of two coordination isomers, due to the position of L on different Ru atoms, confirms the presence in solution of two [Ru3(μ3-Se)2(CO)8(L)] isomers before the attack of the W(CO)3 fragment. Finally, electrochemical measurements show that the substitution of a Ru atom with a W atom in the closo Ru4Se2 cluster core triggers significant changes in the redox activity of the cluster core, which is further modulated by the electronic effects of the peripheral phosphines.