Group 9 and 10 Metal Complexes of an Ylide-Substituted Phosphine: Coordination versus Cyclometalation and Oxidative Addition

[Image: see text] Ylide-substituted phosphines (YPhos) have been shown to be excellent ligands for several transition metal catalyzed reactions. Investigations of the coordination behavior of the YPhos ligand Y(S)PPh(2) (1) [with Y(S) = (Ph(3)P)(SO(2)Tol)C] toward group 9 and 10 metals revealed a surprisingly diverse coordination chemistry of the ligand. With Ni(CO)(4), the formation of a di- as well as tricarbonyl complex is observed depending on the reaction conditions. In [(κP,η(2)-benzene-1)Ni(CO)(2)] the phosphine ligand also coordinates via a phosphonium bound phenyl group to the metal leading to a unique nickel η(2)-arene interaction, which can be viewed as an intermediate state toward P–C bond activation. Full cleavage of the P–C bond takes place with [Rh(COD)Cl](2) leading to a complex salt with [(κP,κO-1)Rh(COD)](+) as cation and a dirhodium trichloride complex anion. Here, Y(S)PPh(2) underwent P–C bond cleavage to thus act as an anionic diphosphine ligand. In contrast, in [(κP,κO-1)Rh(COD)](+) as well as [(κP,κO-1)Rh(CO)Cl], formed from the reaction of 1 with [Rh(CO)(2)Cl](2,) the YPhos ligand acts as bidentate ligand complexing the metal via the phosphine and sulfonyl moiety with an intact PPh(3) unit. A further type of coordination is observed with [Ir(COD)Cl](2). Here, phosphine coordination is accompanied by C–H activation at one of the phosphonium bound phenyl groups leading to a cyclometalated complex.