VINYLIDENE TRANSITION-METAL COMPLEXES .33. A SERIES OF RHODIUM(I) COMPLEXES, INCLUDING CARBENE, VINYLIDENE AND ALLENYLIDENE DERIVATIVES, WITH THE BIFUNCTIONAL ARSINE PR(2)(I)ASCH(2)CH(2)OME AS LIGAND

A series of rhodium(I) complexes containing the new bifunctional arsine ligand Pr(2)(i)AsCH(2)CH(2)OMe I has been prepared. Most of the compounds were obtained from the ethene derivative trans-(RhCl(C2H4) ((Pr2AsCH2CH)-As-i(2)OMe)(2)} 5 which was obtained from [{RhCl(C2H4)(2)}(2)] and I in about 80% yield. The ethene can be displaced by CO, CNBUt, CH2=CHC(O)Me, CH2=CHCO(2)Me, HC=CPh, HC=CCO(2)Me, PhC=CSiMe(3), MeC=CMe, PhC=CMe, MeC=CC=CMe or Me(3)SiC=CC=CSiMe(3) (L) to give the four-co-ordinated rhodium(I) complexes trans-[RhCl(L)(Pr(2)(i)AsCH(2)CH(2)OMe)(2)] almost quantitatively. The reaction of 5 with H-2 affords the dihydride {RhH2Cl(Pr(2)(i)AsCH(2)CH(2)OMe)(2)} which appears to be fluxional in solution. Photolysis of 5 leads to the elimination of CH2=CHOMe and the formation of trans-[RhCl(C2H4) (HAsPr2i)(2)] which is also accessible from 3 and HAsPr2i. The vinylidene complexes trans-[RhCl(=C=CHR)(Pr(2)(i)AsCH(2)CH(2)OMe)(2)] are obtained either on photochemically induced rearrangement of the isomeric alk-1-yne derivatives (R = Ph or CO(2)Me) or directly from 5 and HC=CR (R = Me or Bu(t)). The reaction of 5 with a large excess of HC=CMe or MeC=CBu(t) gives the rhodium(i) allenes trans-[RhCl(CH2=C=CHR) (Pr(2)(i)AsCH(2)CH(2)OMe)(2)] (R = H or Bu(t)). The allenylidene compounds trans-[RhCl(=C=C=CRR') (Pr(2)(i)AsCH(2)CH(2)OMe)(2)] (R = Ph, R' = Ph or C(6)H(4)Me-o) are obtained from the functionalized vinylidene derivatives trans-[RhCl(=C=CHCRR'OH)(Pr(2)(i)AsCH(2)CH(2)OMe)(2)] upon treatment with Al2O3. From trans-[RhCl(=C=C=CRR')(Pr(2)(i)AsCH(2)CH(2)OMe)(2)] and NaC5H5 the half-sandwiches [C5H5Rh(=C=C=CRR')(Pr(2)(i)AsCH(2)CH(2)OMe)] have been prepared. Compound 5 reacts with N(2)CPh(2) and N2C(C(6)H(4)Me-p)(2) to yield the carbene complexes trans-[RhCl(=CR(2))(Pr(2)(i)AsCH(2)CH(2)OMe)(2)] whereas from 5 and N(2)CRC(O)Ph (R = H or Ph) the diazoalkane rhodium compounds trans-[RhCl{N(2)CRC(O)Ph}(Pr(2)(i)AsCH(2)CH(2)OMe)(2)] are obtained.