First donor stabilized-phosphenium rhodium complexes

Asymmetric Cationic Phosphines: Synthesis, Coordination Chemistry, and Reactivity

“…32 Trans-[Rh(α-CgPAmHMe)2(CO)Cl](BF4)2, 1, which was prepared as a yellow solid by standard procedures, showed a ν(CO) stretch at 2020 cm -1 which compares with values of 1965, 2016, 2024, 2003 and 2007 cm -1 for the analogous complexes of PPh3, P(OPh)3, P(pyrrolyl)3, 2-(diphenylphosphino)-1,3-dimethylimidazolium and a trans-chelating imidazoliumphosphine ligand. [33][34][35] This data places the ligand at the strongly π-accepting end of the P-donor range and, whilst accepting that these values can be misleading when a complex is structurally compromised, this is not the case for 1 (Figure 3). The conformity to the square planar ideal is confirmed upon inspection of the structure and associated metrics notably the near-linear Cl-Rh-C and P-Rh-P bond angles of 178.4° and 176.1° and the sum of the angles about the metal which equal 360° with no individual angle more than ±2° from 90°.…”

Recent Advances in Imidazoliumyl‐Substituted Phosphorus Compounds

“…The anion is exchanged to PF 6 − by treatment with K[PF 6 ]. Compared with phosphites (e.g., P(O i Pr) 3 , P(OPh) 3 ), stronger π‐acceptor properties for 84 a – c [PF 6 ] are deduced from the IR stretching frequency of the nickel carbonyl and rhodium carbonyl complexes . This effect can be explained by the positive charge in the imidazoliumyl moiety .…”

“…Compared with phosphites (e.g.,P (OiPr) 3 ,P (OPh) 3 ), [70] stronger p-acceptor properties for 84 a-c[PF 6 ]a re deducedf rom the IR stretching frequency of the nickel carbonyl and rhodium carbonyl complexes. [71] This effect can be explained by the positive charge in the imidazoliumylm oiety. [9] Thus, these types of compounds are used as electron-poorl igandsi no rganometallicc hemistry and homogeneous catalysis, which was thoroughly reviewed by Renaud and Gailland [7] and Chauvin and co-workers.…”

Phosphines and related C–P bonded compounds

“…372 Donor-stabilised phosphenium cations have been shown to behave normally in the formation of P-donor complexes with rhodium(I). 373 Tertiary arsine donors have also been shown to coordinate to phosphenium cations 374 and both tertiary phosphines 375 and tertiary arsines 376 have been shown to form stable complexes with arsenium salts. A simple route to the high purity cyclic triphosphenium cations (175) is provided by the reaction of a phosphorus trihalide with a chelating diphosphine in the presence of cyclohexene, which acts as a halogen-scavenger.…”