A new co-ordination mode for a tetrathia crown ether. Crystal structure of [MoBr(CO)2(Me8[16]aneS4)][MoBr3(CO)4]·C6H14(Me8[16]aneS4= 3,3,7,7,11,11,15,15-octamethyl-1,5,9,13-tetrathiacyclohexadecane)

Abstract

Equimolar quantities of [{MoBr(µ-Br)(CO)₄}₂] and 3,3,7,7,11,11,15,15-octamethyl-1,5,9,13-tetrathiacyclohexadecane (Me₈[16]aneS₄) in CH₂Cl₂ at 20 °C gave the novel seven-co-ordinate cation–anion complex [MoBr(CO)₂(Me₈[16]aneS₄)][MoBr₃(CO)₄] whose molecular structure shows the cation to have a 4 : 3 ‘piano-stool’ geometry in which the Mo atom lies 1.488(2)Å above the plane of the four S atoms, the first example of this structural type.