Alkyl- und arylkomplexe des iridiums und rhodiums XIV. [formula omitted](OPh) 2] 2[P(OPh) 3] und Ir(CH 2SiMe 3)(CO)[P(OMe) 3] 3: reaktionsprodukte des systems Ir(CH 2EMe 3)(CO)(PPh 3) 2/P(OR) 3 (E  C, Si; R  Ph, Me)

Abstract

Iridium alkyls of type Ir(CH 2EMe 3)(CO)(PPh 3) 2 with E  C (I) or Si (II) react with triphenyl phosphite to give the bis-chelate complex IrH[o-C 6H 4OP (OPh) 2] 2[P(OPh) 3] (III). The reaction is presumed to proceed via short-lived pentacoordinate tris-phosphite intermediates Ir(CH 2EMe 3)(CO)[P(OPh) 3] 3 underdoing successive ortho-CH addition and EMe 4 elimination steps. This assumption is strongly supported by the isolation of the derivative Ir(CH 2SiMe 3)(CO)[P(OMe) 3] 3 (IV) obtained from II and P(OMe) 3. According to 31P NMR, complex III adopts a facial-octahedral structure with the P(OPh) 3 ligand trans to one of the metallated ortho-carbon atoms. Compound IV is fluxional at usual temperature, but stereo-chemically rigid at low temperature. From 31P DNMR data at Δ G * value of 29 kJ mol −1 has been derived for the rearrangement process which is shown to be intramolecular. An X-ray study of IV reveals the expected trigonal-bipyramidal ground-state geometry with axial Me 3SiCH 2 and equatorial CO ligands. Selected single-crystal data are: space group P 1 with a 962.8(3), b 1109.1(5), c 1375.9(6) pm, α 83.47(3), β 81.29(3), γ 68.80(3)°, and Z  2; R 0.051 ( R w 0.070) for 4408 unique reflections; d(IrCH 2) 222.9(8), d(IrCO) 187.5(10), d(IrP ax) 226.4(2), d(IrP eq) 226.3(2) and 227.3(2) pm.