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Reactions of bis(iminophosphoranes) with palladium(II) dichloride: Metal-induced tautomerization orthopalladation and unexpected platinum-assisted [2 + 2] cycloaddition of an aryl-nitrile with a phosphinimine moiety

1997; Elsevier BV; Volume: 527; Issue: 1-2 Linguagem: Inglês

10.1016/s0022-328x(96)06684-3

1872-8561

Mandy W. Avis, Milko E. van der Boom, Cornelis J. Elsevier, Wilberth J. J. Smeets, Anthony L. Spek,

Cyclopropane Reaction Mechanisms

Reactions of bis(iminophosphoranyl)methane, CH2(PPh2  N-aryl)2, (BIPM; 1a,b) or 1,1-bis(iminophosphoranyl)ethane (1,1-BIPE; 1e) with Pd- and Pt-dichlorides containing weakly coordinating ligands (L) such as nitriles or cyclo-octadiene, afforded several products depending on the reaction time, type of ligand (1a-c) or nature of the metal. The first reaction observed is a metal-assisted tautomerization of BIPM to aryl-NPPh2CHPPh2NH-aryl. When BIPM reacts with PdCl2(L)2, exclusive formation of the C,N-chelate PdCl2{CH(PPh2  N-aryl)(PPh2NHaryl)} (2a,b) is observed, whereas with 1,1-BIPE (1c) a product mixture consisting of C, N-chelate (2c) and an N,N′-chelate (3) is found. Orthometallation of the four-membered palladacycle (2) took place upon heating. giving the five-membered palladacycle [PdCl2{2-C6H4-PPh(NH[-pTol)-C′H-PPh2(NH-pTol)})-C,C′] (4). The molecular structure of 4 has been determined by X-ray crystallography. Reactions of BIPM (1a,b) with PtCl2(RCN)2 (Rphenyl, p-tolyl) affored entirely different products: the six-membered platinacycles [PtCl(RCN)(arylN(R)NPPl2CHPPb2NHaryl)-C,N]Cl (5) and [PtCl2(arylNC(R)NPPh2NHaryl]-C,N] (6), due to an unexpected 2 + 2 cycloaddition of a nitrile with a PN group.