title: Unprecedented solvent-assisted reactivity of Hydrido W3CuS4 cubane clusters: the non-innocent behaviour of the cluster-core unit.
abstract: Opening the cluster core: Substitution of the chloride ligand in the novel cationic cluster [W(3)CuS(4)H(3)Cl(dmpe)(3)](+) (see figure; dmpe=1,2-bis(dimethylphosphino)ethane) by acetonitrile is promoted by water addition. Kinetic and density functional theory studies lead to a mechanistic proposal in which acetonitrile or water attack causes the opening of the cluster core with dissociation of one of the Cu--S bonds to accommodate the entering ligand.Reaction of the incomplete cuboidal cationic cluster [W(3)S(4)H(3)(dmpe)(3)](+) (dmpe=1,2-bis(dimethylphosphino)ethane) with Cu(I) compounds produces rare examples of cationic heterodimetallic hydrido clusters of formula [W(3)CuClS(4)H(3)(dmpe)(3)](+) ([1](+)) and [W(3)Cu(CH(3)CN)S(4)H(3)(dmpe)(3)](2+) ([2](2+)). An unexpected conversion of [1](+) into [2](2+), which involves substitution of chloride by CH(3)CN at the copper centre, has been observed in CH(3)CN/H(2)O mixtures. Surprisingly, formation of the acetonitrile complex does not occur in neat acetonitrile and requires the presence of water. The kinetics of this reaction has been studied and the results indicate that the process is accelerated when the water concentration increases and is retarded in the presence of added chloride. Computational studies have also been carried out and a mechanism for the substitution reaction is proposed in which attack at the copper centre by acetonitrile or water causes disruption of the cubane-type core. ESI-MS experiments support the formation of intermediates with an open-core cluster structure. This kind of process is unprecedented in the chemistry of M(3)M'Q(4) (M=Mo, W; Q=S, Se) clusters, and allows for the transient appearance of a new coordination site at the M' site which could explain some aspects of the reactivity and catalytic properties of this kind of clusters.
authors.affiliation: Departmento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Universidad de Cádiz, Poligono Río San Pedro, Puerto Real, Cádiz, 11510 Cádiz, Spain.
authors.forename: Andrés G
authors.initials: AG
authors.lastname: Algarra
authors.forename: Marta
authors.initials: M
authors.lastname: Feliz
authors.forename: M Jesús
authors.initials: MJ
authors.lastname: Fernández-Trujillo
authors.forename: Rosa
authors.initials: R
authors.lastname: Llusar
authors.forename: Vicent S
authors.initials: VS
authors.lastname: Safont
authors.forename: Cristian
authors.initials: C
authors.lastname: Vicent
authors.forename: Manuel G
authors.initials: MG
authors.lastname: Basallote
mesh_terms: D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004578:Electron Spin Resonance Spectroscopy; D007700:Kinetics; D015394:Molecular Structure; D013816:Thermodynamics; D017973:Tungsten Compounds / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D017973:Tungsten Compounds; D003300:Copper; C017846:cupric sulfide