Studies of Ligand Additions to Coordinatively Unsaturated Dirhenium Complexes Containing the Bulky PBut3 Ligand

Abstract

Five new complexes were obtained from the reaction of Re3(CO)12(μ-H)3 with PBut3. These are Re2(CO)8(μ-PBut2)(μ-H), 1, Re2(CO)7(μ-PBut2)(PBut2H)(μ-H), 2, HRe(CO)4(PBut3), 3, Re2(CO)6(PBut3)(μ-PBut2)(μ-H), 4, and Re2(CO)5(PBut3)(PBut2H)(μ-PBut2O)(μ-H), 5. Compounds 4 and 5 are electronically unsaturated by the amount of two electrons; namely, one of the metal atoms has an 18-electron configuration and the other metal atom has a 16-electron configuration. Compound 4 adds CO and the nitriles MeCN and PhCN, reversibly, to form the electronically saturated 1:1 adducts Re2(CO)7(PBut3)(μ-PBut2)(μ-H), 6, Re2(CO)6(NCMe)(PBut3)(μ-PBut2)(μ-H), 7, and Re2(CO)6(NCPh)(PBut3)(μ-PBut2)(μ-H), 8, respectively. 13CO labeling studies have shown that the CO ligand that is added to 4 to form 6 is added at the electronically saturated metal atom and one of the originally coordinated CO ligands is shifted to the unsaturated metal atom. Compound 5 also adds 1 equiv of CO to form the complex Re2(CO)6(PBut3)(PBut2H)(μ-PBut2O)(μ-H),...