Backbone modified small bite-angle diphosphines: Synthesis, structure, and DFT evaluation of the thermal activation products based on Os3(CO)10{μ-Ph2PC(Me)2PPh2}

Abstract Addition of 2,2'-bis(diphenylphosphino)propane, Ph 2 PC(Me) 2 PPh 2 (dppmMe 2 ), to Os 3 (CO) 10 (MeCN) 2 at room temperature affords Os 3 (CO) 10 {μ-Ph 2 PC(Me) 2 PPh 2 } ( 1-Me 2 ), whose X-ray diffraction has been established and found to contain a bridging diphosphine ligand. Heating 1-Me 2 in toluene results in the formation of the expected orthometalated addition product Os 3 (CO) 8 {μ 3 -Ph 2 PC(Me) 2 P(Ph)C 6 H 4 }(μ-H) ( 2-Me 2 ) in only trace amounts, with the face-capped cluster Os 3 (CO) 9 {μ 3 -PhPC(Me) 2 P(Ph)C 6 H 4 } ( 3-Me 2 ) formed as the major product as a result of elimination of benzene. The conversion of 1-Me 2 to 2-Me 2 has been investigated by density functional theory (DFT) calculations and the potential energy surface has been mapped out. The observed reactivity in the dppmMe 2 -substituted cluster 1-Me 2 is compared with the related dppmH 2 - and dppmHMe-substituted triosmium complexes.