C, C coordination mode in comparison with C, P coordination mode in six and seven pallada- and platinacycle complexes of phosphorous ylide; synthesis, X-ray and theoretical studies

Abstract

New symmetrical [p-CN-C6H4C(O)CH2PPh2(CH2)2PPh2CH2C(O)C6H4-p-CN]Br2 (1) and unsymmetrical [PPh2(CH2)2PPh2CH2C(O)C6H4-p-CN]Br (2) phosphonium salts were prepared by reacting Bis(diphenylphosphino)ethane (dppe) with p-CN-C6H4C(O)CH2Br in acetone, in 1:2 and 1:1 ratios, respectively. Treatment of these salts with an appropriate alkali led to symmetrical p-CN-C6H4C(O)C(H)PPh2(CH2)2PPh2C(H)C(O)C6H4-p-CN (3) and unsymmetrical PPh2(CH2)2PPh2C(H)C(O)C6H4-p-CN (4) ylides.The reaction of 3 and 4 with [MCl2(cod)] (M = Pd or Pt; cod = 1,5-cyclooctadiene) in 1:1 ratio, using dichloromethane as a solvent, led to mononuclear seven membered metallocyclic ring complexes ([MCl2(p-CN-C6H4C(O)C(H)PPh2(CH2)2PPh2..