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Synthesis and reactivity of homo- and hetero-dimetallic complexes bridged by diphenyl-2-pyridylphosphine and hydrides: regioselectivity of alkyne insertion into unsaturated M1(micro-PPh2Py)(micro-H)2M2 moieties.

Research paper by Yoshinori Y Takahashi, Naoaki N Murakami, Ken-Ichi K Fujita, Ryohei R Yamaguchi

Indexed on: 05 Mar '09Published on: 05 Mar '09Published in: Dalton Transactions



Abstract

New homo- and hetero-dimetallic complexes bridged by diphenyl-2-pyridylphosphine and hydrides [(CpIr)(micro-PPh(2)Py)(mu-H)(2)(MCp)][OTf](n) (: M = Ir, n = 2; : M = Rh, n = 2; : M = Ru, n = 1) were synthesized. The reactions of with terminal alkynes gave micro-vinyl complexes [(CpIr)(micro-PPh(2)Py)(micro-H)(micro-C(R)=CH(2))(IrCp)][OTf](2) (: R = H; : R = CO(2)Me; : R = Ph) and [(CpIr)(micro-PPh(2)Py)(micro-H)(micro-CH[double bond, length as m-dash]CHR)(IrCp)][OTf](2) (: R = SiMe(3); R = Ph). The reactions of with alkynes gave [(CpIr)(micro-PPh(2)Py)(micro-H)(micro-C(R)=CH(2))(RhCp)][OTf](2) (: R = H; : R = CO(2)Me; : R = Ph), two of which are in equilibrium with [(CpIr)(mu-PPh(2)Py)(micro-H)(micro-CH(2)=C(CO(2)Me))(RhCp)][OTf](2) () and [(CpIr)(micro-PPh(2)Py)(micro-H)(micro-CH(2)=C(Ph))(RhCp)][OTf](2) () at 50 degrees C, respectively. The reactions of with alkynes gave [(CpIr)(micro-PPh(2)Py)(micro-H)(micro-CH(2)=C(R))(RuCp)][OTf] (: R = CO(2)Me; : R = Ph). Plausible pathways for the insertion of alkynes to the metal-hydride bonds and the interconversion of the micro-vinyl complexes are discussed. Structures of the cationic parts of 3, 8, 9, 13b, 14b and 15b have been confirmed by X-ray analysis.