C–P vs C–H Bond Cleavage of Triphenylphosphine at Platinum(0): Mechanism of Formation, Reactivity, Redox Chemistry, and NMR Chemical Shift Calculations of a μ-Phosphanido Diplatinum(II) Platform

Abstract

Transition-metal phosphanides M−PR 2 are key intermediates in catalytic C−P bond functionalization. M−PR 2 formation from tertiary phosphines through P−C bond cleavage widens the scope beyond P−H functionalized substrates, but mechanistic understanding of this reaction still is fragmentary. Starting from a defined coordination complex has allowed monitoring the reaction of a Pt-PPh 3 moiety and Pt(0) by NMR spectroscopy. Initial Pt(0) transfer is rate-limiting and leads to products from PPh 3 -borne ortho-C−H and C−P bond cleavage along kinetically distinct pathways. Albeit kinetically favored, the reversibility of C−H bond cleavage eventually leads to thermodynamically preferred C−P bond scission. This pathway affords a robust [Pt(μ-PPh 2 )Pt] core structure whose redox chemistry and reactivity toward external ligands are reported. Organometallic products have been substantiated by a combination of magnetic resonance and absorption spectroscopies, X-ray diffraction, and DFT computations.

Modulating Effect of Ligand Charge on the Electronic Properties of 2Ni–2S Structures and Implications for Biological 2M–2S Sites

“…The spatial trans alignment of two arylthiolates across the central π-system renders the 1,4-terphenyldithiolate a suitable platform for detailed studies of the electronic properties of 2Ni–2S structures as it can bind the metals in different formal oxidation states, coordination numbers, and geometries, ,, which had been beneficial to mechanistic work on the skeletal (dis)­assembly of 2Ni–2S cores. , Preserving the principal η 2 :η 2 :μ-coordination mode while converting the arene into cyclohexadienide minimizes structural effects that may bias the suspected effect of donor strength on the electronic properties of the 2Ni–2S core. DFT computational analysis relates the thermodynamic preference of arene over cyclohexadienide coordination to [2Ni 1.5+ -2S] + inferred from electrochemical and solid-state structure data to the reduced electronic coupling of the Ni atoms in 2 .…”

Predicting Pt-195 NMR Chemical Shift and 1J(195Pt-31P) Coupling Constant for Pt(0) Complexes Using the NMR-DKH Basis Sets

“…Despite this difficulty, some works on the theoretical prediction of δ 195 Pt and 1 J 195 Pt-L for Pt(II) and Pt(IV) complexes can be found in the literature [18][19][20][21][22][23][24][25][26]. However, computational studies on NMR prediction of Pt-195 in Pt(0) complexes are still very scarce [27].…”