Acceptor Pincer Coordination Chemistry of Platinum: Reactivity Properties of (<sup>CF<sub>3</sub></sup>PCP)Pt(L)<sup>+</sup> (L = NC<sub>5</sub>F<sub>5</sub>, C<sub>2</sub>H<sub>4</sub>)
作者:Jeramie J. Adams、Navamoney Arulsamy、Dean M. Roddick
DOI:10.1021/om8008876
日期:2009.2.23
Synthetic strategies toward the synthesis of electron-poor pincer complexes ((PCP)-P-CF3)PtH and ((PCP)-P-CF3)Pt(eta(2)-H-2)(+) are described. Metathesis of ((PCP)-P-CF3)PtCl with hydride reagents does not lead to ((PCP)-P-CF3)PtH; ((PCP)-P-CF3)PtCl with KH in tetrahydrofuran (THF) afforded an unusual metallated bimetallic pincer product ((PCP)-P-CF3)Pt[kappa(1)-C,kappa P3-,C,P-2,6-(CHP(CF3)(2))(CH2P(CF3)(2))-C6H3]PtCl, which has been structurally characterized. Chloride abstraction from ((PCP)-P-CF3)PtCl or protonolysis of ((PCP)-P-CF3)PtMe in the presence of H-2 gives the structurally characterized hydride-bridged dimer ((PCP)-P-CF3)Pt}(2)(mu-H)(+). In the presence of trapping ligands H2O, C2H4, or pentafluoropyridine, the corresponding complexes ((PCP)-P-CF3)Pt(L)(+) (L = H2O, C2H4, NC5F5) are cleanly produced and have been structurally characterized. The C2H4 and NC5F5 adducts may be alternatively prepared by methide abstraction from (CF3PCP)PtMe with Ph3C+B(C6F5)(4)(-) in the presence of trapping ligand. Evidence for the transient formation of ((PCP)-P-CF3)PtH from treatment of ((PCP)-P-CF3)PtCl or ((PCP)-P-CF3)Pt(NC5F5)(+) with Et3Si+B(C6F5)(4)(-) is presented. ((PCP)-P-CF3)Pt(C2H4)(+) serves as a catalyst for ethylene hydrogenation (0.30 turnovers h(-1), 70 degrees C) and hydrosilation with Et3SiH (460 turnovers h(-1), RT) and Cl3SiH (5 turnovers h(-1), RT). At elevated temperatures, ((PCP)-P-CF3)Pt(C2H4)(+) also exhibits limited ethylene dimerization activity (0.07 turnovers h(-1), 155 degrees C and 1-butene isomerization (0.9 turnovers h(-1), 80 degrees C).
Preparation of an unusual fluoroalkyl phosphinoyl chelate complex, {k3-P,C,P,k1-O-(CF3)2PCH2C6H3CH2P(CF3)O}2Pt2
作者:Jeramie J. Adams、Navamoney Arulsamy、Dean M. Roddick
DOI:10.1016/j.ica.2008.08.015
日期:2009.4
Electron poor cationic complexes [((PCP)-P-CF3)Pt(L)](+) (where L = CO, NC5F5, or acetone) react with H2O in polar solvents via selective hydrolysis of a single P-CF3 substituent to afford the spectroscopically- characterized phosphinoyl-bridged complex k(3)-P,C,P,k(1)-O-(CF3)(2)PCH2C6H3CH2P(CF3)O}(2)Pt-2 (1) in good yield. X-ray diffraction confirms the presence of a six-member Pt-P-O-Pt-P-O ring in a chair conformation. The presumed intermediate aqua complex, ((PCP)-P-CF3)Pt(H2O)(+), is stable in dichloromethane, but when dissolved in more polar solvents readily converts to 1. (C) 2008 Elsevier B. V. All rights reserved.