Alkyl- und arylkomplexe des iridiums und rhodiums XIV. (OPh)2]2[P(OPh)3] und Ir(CH2SiMe3)(CO)[P(OMe)3]3: reaktionsprodukte des systems Ir(CH2EMe3)(CO)(PPh3)2/P(OR)3 (E C, Si; R Ph, Me)
1983; Elsevier BV; Volume: 251; Issue: 1 Linguagem: Inglês
10.1016/0022-328x(83)80250-2
ISSN1872-8561
Autores Tópico(s)Catalytic Cross-Coupling Reactions
ResumoAbstract Iridium alkyls of type Ir(CH2EMe3)(CO)(PPh3)2 with E C (I) or Si (II) react with triphenyl phosphite to give the bis-chelate complex IrH[o-C 6 H 4 OP (OPh)2]2[P(OPh)3] (III). The reaction is presumed to proceed via short-lived pentacoordinate tris-phosphite intermediates Ir(CH2EMe3)(CO)[P(OPh)3]3 underdoing successive ortho-CH addition and EMe4 elimination steps. This assumption is strongly supported by the isolation of the derivative Ir(CH2SiMe3)(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 ΔG* 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 Me3SiCH2 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 (Rw 0.070) for 4408 unique reflections; d(IrCH2) 222.9(8), d(IrCO) 187.5(10), d(IrPax) 226.4(2), d(IrPeq) 226.3(2) and 227.3(2) pm.
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