Reactions of the lightly-stabilized triosmium cluster Os3(CO)8{μ3-Ph2PCH(Me)P(Ph)C6H4}(μ-H) with two-electron donor ligands

Abstract

Reactions of the lightly-stabilized Os3(CO)8{μ3-Ph2PCH(Me)P(Ph)C6H4}(μ-H) (1) with dihydrogen and representative 2-electron donor ligands, PPh3 and P(OMe)3, are described. With PPh3, the phosphine-adduct Os3(CO)8(PPh3){μ3-Ph2PCH(Me)P(Ph)C6H4}(μ-H) (2) is initially formed but this reacts further via three separate pathways: adding a second equivalent of PPh3 to yield Os3(CO)8(PPh3)2{μ-Ph2PCH(Me)PPh2} (5), losing a CO ligand with concomitant phosphine migration to afford Os3(CO)7(PPh3){μ3-Ph2PCH(Me)P(Ph)C6H4}(μ-H) (3) or adding a CO ligand to yield Os3(CO)9(PPh3){μ-Ph2PCH(Me)PPh2} (4). In contrast, reaction with P(OMe)3 leads to the simple stepwise formation of the mono- and bis-phosphite adducts, Os3(CO)8{P(OMe)3}{μ3-Ph2PCH(Me)P(Ph)C6H4}(μ-H) (6) and Os3(CO)8{P(OMe)3}2{μ-Ph2PCH(Me)PPh2} (7), respectively. Addition of dihydrogen to 1 cleanly affords the unsaturated 46-electron cluster Os3(CO)8{μ-Ph2PCH(Me)PPh2}(μ-H)2 (8). All the new clusters have been spectroscopically characterized together with single crystal X-ray diffraction studies of 2, 3 and 8.