Rhodium(I) and rhodium(III) complexes formed by coordination and C-H activation of bulky functionalized phosphanes

The reaction of [{RhCl-(C8H14)(2)}(2)] (2) with iPr(2)PCH(2)CH(2)C(6)H(5) (L-1) led, via the isolated dimer [{RhCl(C8H14)(L-1)}(2)] (3), to a mixture of three products 4a-c, of which the dinuclear complex [{RhCl(L-1)(2)}(2)] (4a) was characterized by X-ray crystallography. The mixture of 4a-c reacts with CO, ethene, and phenylacetylene to give the square-planar compounds trans[RhCl(L)(L-1)(2)] (L = CO (5), C2H4 (6), C=CHPh (9)). The corresponding allenylidene(chloro) complex trans[RhCl(=C=C=CPh2)(L-1)(2)] (11), obtained from 4 a-c and HCdropCC(OH)Ph-2 via trans-[RhCl{=C=CHC(OH)Ph-2}-(L-1)(2)] (10), could be converted stepwise to the related hydroxo, cationic aqua, and cationic acetone derivatives 12-14, respectively. Treatment of 2 and [{RhCl(C2H4)(2)}(2)] (7) with two equivalents of tBu(2)PCH(2)CH(2)C(6)H(5) (L-2) gave the dimers [{RhCl(C8H14)(L-2)}(2)] (15) and [{RhCl(C2H4)(L-2)}(2)] (16), which both react with L-2 in the molar ratio of 1:2 to afford the five-coordinate aryl(hydrido)rhodium(m) complex [RhHCl-(C6H4CH2CH2PtBu2-kappa(2)C,P)(L-2)] (17) by C-H activation. The course of the reactions of 17 with CO, H-2, PhCdropCH, HCl, and AgPF6, leading to the compounds 19-21, 24, and 25a, respectively, indicate that the coordinatively unsaturated isomer of 17 with the supposed composition [RhCl(L-2)(2)] is the reactive species. Labeling experiments using D-2, DCl, and PhCdropCD support this proposal. With either [Rh(C8H14) (eta(6)-L-2-kappaP]PF6 or [Rh(C2H4)(eta(6)-L-n-kappaP]PF6 (n = 1 and 2) as the starting materials, the corresponding halfsandwich-type complexes 27, 28, and 32 were obtained. The nonchelating counterpart of the dihydrido compound 32 with the composition [RhH2(PiPr(3))-(eta(6)-C6H6)]PF6 (35) was prepared step-wise from [Rh(C2H4)(PiPr(3)) (eta(6)-C6H6)]-PF6 and H-2 in acetone via the tris(solvato) species [RhH2(PiPr(3))(acetone)(3)]PF6 (34) as intermediate. The synthesis of the bis(chelate) complex[Rh(eta(4)-C8H12)-(C6H5OCH2CH2PtBu2-kappa(2)O,P)]BF4 (39) is also described. Besides 4a, the compounds 17, 25 a, and 39 have been characterized by X-ray crystal structure analysis.