A series of rhodium(I) complexes, including carbene, vinylidene and allenylidene derivatives, with the bifunctional arsine Pri2AsCH2CH2OMe as ligand

Abstract

A series of rhodium(I) complexes containing the new bifunctional arsine ligand Prⁱ₂AsCH₂CH₂OMe 1 has been prepared. Most of the compounds were obtained from the ethene derivative trans-{RhCl(C₂H₄)(Prⁱ₂AsCH₂CH₂OMe)₂}5 which was obtained from [{RhCl(C₂H₄)₂}₂] and 1 in about 80% yield. The ethene can be displaced by CO, CNBu^t, CH₂CHC(O)Me, CH₂CHCO₂Me, HCCPh. HCCCO₂Me, PhCCSiMe₃, MeCCMe, PhCCMe, MeCCCCMe or Me₃SiCCCCSiMe₃(L) to give the four-co-ordinated rhodium(I) complexes trans-[RhCI(L)(Prⁱ₂AsCH₂CH₂OMe)₂] almost quantitatively. The reaction of 5 with H₂ affords the dihydride (RhH₂Cl(Prⁱ₂AsCH₂CH₂OMe)₂ which appears to be fluxional in solution. Photolysis of 5 leads to the elimination of CH₂CHOMe and the formation of trans-[RhCl(C₂H₄)(HAsPrⁱ₂)₂] which is also accessible from 3 and HAsPr¹₂. The vinylidene complexes trans-[RhCl(CCHR)(Prⁱ₂AsCH₂CH₂OMe)₂] are obtained either on photochemically induced rearrangement of the isomerie alk-1-yne derivatives (R = Ph or CO₂Me) or directly from 5 and HCCR (R = Me or Bu^t). The reaction of 5 with a large excess of HCCMe or MeCCBu^t gives the rhodium(I) allenes trans-[RhCl(CH₂CCHR)(Prⁱ₂AsCH₂CH₂OMe)₂](R = H or Bu^t). The allenylidene compounds trans-[RhCl(CCCRR′)(Prⁱ₂AsCH₂CH₂OMe)₂](R = Ph, R′= Ph or C₆H₄Me-O) are obtained from the functionalized vinylidene derivatives trans-[RhCl(CCHCRR′OH)(Prⁱ₂AsCH₂CH₂OMe)₂] upon treatment with Al₂O₃. From trans-[RhCl(CCCRR′)(Prⁱ₂AsCH₂CH₂OMe)₂] and NaC₅H₅ the half-sandwiches [C₅H₅Rh(CCCRR′)(Prⁱ₂AsCH₂CH₂OMe)] have been prepared. Compound 5 reacts with N₂CPh₂ and N₂C(C₆H₄Me-p)₂ to yield the carbene complexes trans-[RhCl(CR₂)(Prⁱ₂AsCH₂CH₂OMe)₂] whereas from 5 and N₂CRC(O)Ph (R = H or Ph) the diazoalkane rhodium compounds trans-[RhCl(N₂CRC(O)Ph)(Prⁱ₂AsCH₂CH₂OMe)₂] are obtained.