Large-ring and cyclometalated rhodium complexes from some medium-chain .alpha.,.omega.-diphosphines

Abstract

Bu'aPtCHzlsPBu'i reacts with RhCl3-3H20 in ethanol to give a mixture of the binuclear 16-atom ring complex [RhaHaCUIBukPCHzCI-nCHsCI-hCl-hPBukizL which exists in solution as a mixture of two rotamers: a cyclometalated complex [RhHCljBukfrc^C^CHCl-hCI-nPBukl] of configuration 6 and another species, probably an olefin complex [RfiCl{Bu'2PCH2CH2CH=CHCH2PBu'2|] (8). A similar reaction in refluxing tetrahydrofuran gave pure 6. Treatment of the binuclear hydrido complex [Rt^^CUlBukPC^CThCTHC^C^PBukia] with 2-methylpyridine promoted cyclometalation to give 6. This cyclometalated hydride ( 6) is fluxional and at ambient temperature rapid C-H fission occurs, rendering

Synthesis and Characterization of Dihydrogen(olefin)osmium Complexes with (E)-Ph2P(CH2)2CH=CH(CH2)2PPh2

“…In particular, the 1 H NMR spectrum (in C 6 D 6 ) showed the olefinic proton signal at δ = 5.4 ppm, while the 31 P{ 1 H} NMR spectrum (in C 6 D 6 ) showed a singlet at δ = −17.0 ppm. The closely related ligand ( E )‐( t Bu) 2 P(CH 2 ) 2 CH=CH(CH 2 ) 2 P( t Bu) 2 has also been reported previously 18…”

Iridium‐Catalyzed H/D Exchange at Vinyl Groups without Olefin Isomerization

“…[17] The structure of 7 is shown in Figure 4. The olefin on the dehydrogenated ligand [18] is bound to the iridium in an h 2 manner, and the coordination geometry around the metal is best described as square planar.…”

Catalytic alkane dehydrogenations

“…These pincer complexes were originally prepared by Shaw and co-workers [46] in 1970s. They reported the synthesis of bis(phosphine)-based pincer Rh and Ir hydride chloride complexes (tBu 4 PCP)M(H)Cl (tBu 4 PCP = C 6 H 3 (CH 2 PtBu 2 ) 2 , M = Rh, 11a; M = Ir, 11b) containing tert-butyl substituents on the phosphorus atoms [46][47][48][49][50][51][52]. Such PCP complexes are highly thermally stable and do not decompose within one week at 200°C [53].…”