Vinyliden-übergangsmetallkomplexe XXXVIII. Alkin-, alkinyl-, vinyliden-, allenyliden- und benzyl-rhodiumkomplexe mit dem phosphinoether iPr 2PCH 2CH 2OMe als ein- und zweizähnigen Liganden

Abstract

The monomeric four-coordinate rhodium(I) compound [RhCiL 2] (L = iPr 2PCH 2CH 2 OMe ) ( 1) reacts with terminal alkynes HCCR ( R = tBu, Tol, CH(Ph)OH, C(Ph) 2 OH, C( iPr ) 2 OH ) to give the vinylidene complexes trans-[RhCl(= C = CHRL)L 2] ( 5–10) as the final products. Whereas for R = C(Ph) 2OH, the stepwise conversion of the initially formed square-planar alkyne derivative 2 to the octahedral alkynyl(hydrido)compound 3 and further to the vinylidene complex 5 has been confirmed, for R = C( iPr ) 2 OH a complete rearrangement of the isolated compound [RhH(C  CR) Cl( κ 2( P, O)-L)] ( 4) to the vinylidenerrhodium isomer 6 could not be achieved. The abstraction of water from 10 (R = C(Me) 2OH) induced by catalytic amounts of CF 3CO 2H leads to the formation of the vinylvinylidenerhodium(I) compound trans-[RhCl(= C = CHC(Me) = CH 2)L 2] ( 11); on contrast, the corresponding reaction of 5 (R = C(Ph) 2OH) with acidic Al 2O 3 yields the allenylidene complex trans-[RhCl(= C = C = CPh 2L 2] ( 12). The η[ su3-benzylrhodium(I) compounds [Rh( η 3-CH 2C 6H 4-4-R)L 2] ( 14,15), which are prepared from 1 and Grignard reagents 4-RC 6H 4CH 2MgCl (R = H, CH 3), react with CO to give the η 1-benzyl derivatives [Rh( η 1-CH 2C 6H 4-4-R)(COLL 2] ( 16, 17). The reaction of 14 with HCCC( iPr) 2OH yields the bis(alkynyl)hydridorhodium(III) compound [RhH(CCR) 2L 2] ( R = C( iPr) 2 OH) ( 20), the structure of which has been determined by X-ray crystallography. While compound 14 reacts with HCCC(Me) 2OH under an ethene atmosphere to give trans-[Rh(CC- -C(Me) 2OH)(C 2H 4)L 2] ( 21), on treatment of 14 with HCCTol in the presence of HBF 4 the cationic complex [RhL 2]BF 4 ( 22a) is obtained. The corresponding PF 6 salt 22b is prepared from [Rh(C 8H 14) 2(OCMe 2) 2) 2]PF 6 and L.