Rhodium(I) and Rhodium(III) Complexes Formed by Coordination and CH Activation of Bulky Functionalized Phosphanes

✍ Scribed by Giuseppe Canepa; Carsten D. Brandt; Kerstin Ilg; Justin Wolf; Helmut Werner

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 329 KB
• Volume: 9
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/chem.200204623

✦ Synopsis

Abstract

The reaction of [{RhCl(C~8~H~14~)~2~}~2~] (2) with __i__Pr~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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 __t__Bu~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~P__t__Bu~2~‐κ^2^C,P)(L^2^)] (17) by CH activation. The course of the reactions of 17 with CO, H~2~, PhC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CD support this proposal. With either [Rh(C~8~H~14~)(η^6^‐L^2^‐κP]PF~6~ or [Rh(C~2~H~4~)(η^6^‐L^n^‐κP]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~(P__i__Pr~3~)(η^6^‐C~6~H~6~)]PF~6~ (35) was prepared stepwise from [Rh(C~2~H~4~)(P__i__Pr~3~)(η^6^‐C~6~H~6~)]PF~6~ and H~2~ in acetone via the tris(solvato) species [RhH~2~(P__i__Pr~3~)(acetone)~3~]PF~6~ (34) as intermediate. The synthesis of the bis(chelate) complex [Rh(η^4^‐C~8~H~12~)(C~6~H~5~OCH~2~CH~2~P__t__Bu~2~‐κ^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.