Rhodium(I) and Rhodium(III) Complexes Formed by Coordination and CH Activation of Bulky Functionalized Phosphanes

Abstract

The reaction of [[RhCl(C(8)H(14))(2)](2)] (2) with iPr(2)PCH(2)CH(2)C(6)H(5) (L(1)) led, via the isolated dimer [[RhCl(C(8)H(14))(L(1))](2)] (3), to a mixture of three products 4 a-c, of which the dinuclear complex [[RhCl(L(1))(2)](2)] (4 a) was characterized by Xray 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), C(2)H(4) (6), C=CHPh (9)). The corresponding allenylidene(chloro) complex trans-[RhCl(=C=C=CPh(2))(L(1))(2)] (11), obtained from 4 a-c and HC triple bond CC(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(C(2)H(4))(2)](2)] (7) with two equivalents of tBu(2)PCH(2)CH(2)C(6)H(5) (L(2)) gave the dimers [[RhCl(C(8)H(14))(L(2))](2)] (15) and [[RhCl(C(2)H(4))(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(III) complex [RhHCl(C(6)H(4)CH(2)CH(2)PtBu(2)-kappa(2)C,P)(L(2))] (17) by C-H activation. The course of the reactions of 17 with CO, H(2), PhC triple bond CH, HCl, and AgPF(6), leading to the compounds 19-21, 24, and 25 a, 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 PhC triple bond CD support this proposal. With either [Rh(C(8)H(14))(eta(6)-L(2)-kappaP]PF(6) or [Rh(C(2)H(4))(eta(6)-L(n)-kappaP]PF(6) (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 [RhH(2)(PiPr(3))(eta(6)-C(6)H(6))]PF(6) (35) was prepared stepwise from [Rh(C(2)H(4))(PiPr(3))(eta(6)-C(6)H(6))]PF(6) and H(2) in acetone via the tris(solvato) species [RhH(2)(PiPr(3))(acetone)(3)]PF(6) (34) as intermediate. The synthesis of the bis(chelate) complex [Rh(eta(4)-C(8)H(12))(C(6)H(5)OCH(2)CH(2)PtBu(2)-kappa(2)O,P)]BF(4) (39) is also described. Besides 4 a, the compounds 17, 25 a, and 39 have been characterized by Xray crystal structure analysis.

A Rhodium Complex with One Rh⋅⋅⋅CC and One Rh⋅⋅⋅HC Agostic Bond

“…[21] Addition of H 2 and benzene to 1 results in oxidative addition of H 2 and the elimination of Binor-S to afford the rhodium(iii) complex [Rh(PiPr 3 )(H 2 )(h 6 -C 6 H 6 )] [BAr 5). [22] Finally, complex 1 is also an isolated resting state of a norbornadiene dimerization catalyst, as addition of excess of diene results in the rapid formation of Binor-S and related dimerization products.…”

Cationic rhodium mono-phosphine fragments partnered with carborane monoanions [closo-CB11H6X6]– (X = H, Br). Synthesis, structures and reactivity with alkenes

“…This signal is similar to that reported for [Rh(P i Pr 3 )(H) 2 (OCMe 2 ) 3 ][PF 6 ]. 17 The relative sharpness of this signal demonstrates that these hydrides are not interacting with the borane cage. In addition to these signals, dissolved H 2 is observed at d 4.55 as a broad signal, indicating that exchange between H 2 and 3b is relatively slow on the NMR timescale.…”

“…Related mono-phosphine complexes, without a carborane anion, have been reported by the groups of Oro and Werner. These complexes contain octahedral {M(PR 3 )H 2 } + fragments ligated with acetonitrile, acetone or arene ligands, and examples include: [Ir(P i Pr 3 )(NCMe) 3 H 2 ][BF 4 ], 14 [Ir(P i Pr 3 )(g 6 -C 6 H 6 )H 2 ][BF 4 ], 15 [Rh(P i Pr 3 )(L) 3 H 2 ][PF 6 ] (L = acetone, g 6 -C 6 H 6 ) 16, 17 (Chart 1). Some of these complexes have proved to be useful in alkene, 14,18 alkyne 19 and imine 15,18 hydrogenation, C-H and C-C activation.…”

A Rhodium Complex with One Rh⋅⋅⋅CC and One Rh⋅⋅⋅HC Agostic Bond

“…However, addition of cyclooctene (coe) and benzene to a dichloromethane solution of 1 does result in the facile displacement of Binor‐S to form the rhodium( I ) complex [Rh(P i Pr 3 )(η 2 ‐C 8 H 14 )(η 6 ‐C 6 H 6 )][BAr F 4 ] ( 4 ) 21. Addition of H 2 and benzene to 1 results in oxidative addition of H 2 and the elimination of Binor‐S to afford the rhodium( III ) complex [Rh(P i Pr 3 )(H 2 )(η 6 ‐C 6 H 6 )][BAr F 4 ] ( 5 ) 22. Finally, complex 1 is also an isolated resting state of a norbornadiene dimerization catalyst, as addition of excess of diene results in the rapid formation of Binor‐S and related dimerization products.…”