Novel access to carbodiphosphoranes in the coordination sphere of group 10 metals: template synthesis and protonation of PCP pincer carbodiphosphorane complexes of C(dppm)2

Abstract

In a novel template synthesis of carbodiphosphoranes (CDPs), the phosphine functionalized CDP ligand C(dppm)(2) (dppm = Ph(2)PCH(2)PPh(2)) is formed in the coordination sphere of group 10 metals from CS(2) and 4 equivalents of dppm. The products are the PCP pincer complexes [M(Cl)(C(dppm)(2)-κ3P,C,P)]Cl (M = Ni, Pd, Pt) and 2 equivalents of dppmS. The compound C(dppm)(2), which is composed of a divalent carbon atom and two dppm subunits, represents a new PCP-type pincer ligand with the formally neutral carbon Lewis base of the CDP functionality as the central carbon. Treatment of [M(Cl)(C(dppm)(2)-κ3P,C,P)]Cl (M = Pd, Pt) with hydrochloric acid results in protonation at the CDP carbon atom and the formation of the PCP pincer complexes [M(Cl)(CH(dppm)(2)-κ3P,C,P)]Cl(2) (M = Pd, Pt). The PCP pincer ligand [CH(dppm)(2)](+) involves a formally cationic central carbon donor. The reaction of [Ni(Cl)(C(dppm)(2)-κ3P,C,P)]Cl with HCl leads to the extrusion of NiCl(2) and formation of the diprotonated CDP compound [CH(2)(dppm)(2)]Cl(2), from which the monoprotonated conjugate base [CH(dppm)(2)]Cl is obtained upon addition of bases, such as NH(3). The crystal structures of [M(Cl)(C(dppm)(2)-κ3P,C,P)]Cl (M = Ni, Pd, Pt), [Ni(Cl)(C(dppm)(2)-κ3P,C,P)](2)[NiCl(4)], [M(Cl)(CH(dppm)(2)-κ3P,C,P)]Cl(2) (M = Pd, Pt) as well as [CH(2)(dppm)(2)]Cl(2) and [CH(dppm)(2)]Cl are presented. A comparison of the solid state structures reveals interesting features, e.g. infinite supramolecular networks mediated by C-H···Cl hydrogen bond interactions and an unexpected loss of molecular symmetry upon protonation in the complexes [M(CH(dppm)(2)-κ3P,C,P)(Cl)]Cl(2) (M = Pd, Pt) as a result of the flexible ligand backbone. Additionally the new compounds were characterized comprehensively in solution by multinuclear (31)P, (13)C and (1)H NMR spectroscopy: Several spectroscopic parameters show a striking variability in particular regarding the carbodiphosphorane functionality. Furthermore the compound [Ni(Cl)(C(dppm)(2)-κ3P,C,P)]Cl was examined by cyclic voltammetry (CV) and could be shown to display quasi-reversible oxidative as well as reductive behaviour.

Organophosphines in organoplatinum complexes – Structural aspects of trans -PtP 2 CCl derivatives

“…Each tridentate ligand created two metallocyclic rings with common C atom. A pair of five-membered rings are most common, with the mean values of PePteC bite angles of 83 (PC 2 C) [97e104], 86 (POCC) [105], and 83.8 (PCPC) [107]. In Ref.…”

Ligands Based on Phosphine‐Stabilized Aluminum(I), Boron(I), and Carbon(0)

“…However,t ransitionmetal complexes with such ligandsare currently limited to rhodium, nickel, palladium, platinum,a nd gold. [21][22][23][24][25][26][27][28] Reactivity patterns of complexes 1a Ph -1 d Ph Next, we evaluated whether the unusual reactivity pattern of a reversible BÀHr eductive elimination in the iron(II) complex with the boron-based ligand could be transferred to other donor groups as well. Therefore, the relative stability of the corresponding isomersw as calculated at the B97D/def2-TZVPP level of theory.W ei nvestigated reductivep rotont ransfer from A (Scheme 1), which,i nt he case of X = AlH, BH, and CH, leads to cleavage of the bond to the formed iron(0)a tom in B.F or X = C, proton transfer yields an iron(0) complex with protonated CDP as ac entral donor group (isomer C).…”

Syntheses and crystal structures of [IrIII{C(CHCO2Et)(dppm)2-κ4 P,C,C′,P′}ClH]Cl·2.75CH2Cl2 and its derivatives, [IrIII{C(CHCO2Et)(dppm)2-κ4 P,C,C′,P′}(CH2CO2Et)Cl]Cl·CH3OH·0.5H2O, [IrIII{C(CHCO2Et)(dppm)2-κ4

“…The carbodiphosphorane C atom can be considered as a fourelectron donor, and accordingly enables the coordination of two Lewis acids, such as protons or different metal cations. Our interests focus on the combination of a carbodiphosphorane pincer ligand system, [CH(dppm) 2 ]Cl (dppm = 1,1-bis(diphenylphosphino)methane; Reitsamer et al, 2012), with reactive functionalities to enter new reaction pathways, to create new complexes and to analyse in detail the new properties obtained. In general, C-C coupling reactions can be induced via the use of diazo compounds such as ethyl diazoacetate.…”