Formation of Heterobimetallic Complexes by Addition of d¹⁰-Metal Ions to [(Me₃P)_xM(2-C₆F₄PPh₂)₂] (x = 1, 2; M = Ni and Pt): A Synthetic and Computational Study of Metallophilic Interactions

Treatment of the bis(chelate) complexes trans-[M(κ²-2-C₆F₄PPh₂)₂] (trans-1M; M = Ni, Pt) and cis-[Pt(κ²-2-C₆F₄PPh₂)₂] (cis-1Pt) with equimolar amounts or excess of PMe₃ solution gave complexes of the type [(Me₃P)_xM(2-C₆F₄PPh₂)₂] (x = 2: 2M^a, 2M^b x = 1: 3M^a, 3M^b; M = Ni, Pt). The reactivity of complexes of the type 2M and 3M towards monovalent coinage metal ions (M’ = Cu, Ag, Au) was investigated next to the reaction of 1M towards [AuCl(PMe₃)]. Four different complex types [(Me₃P)₂M(µ-2-C₆F₄PPh₂)₂M’Cl] (5MM’; M = Ni, Pt; M’ = Cu, Ag, Au), [(Me₃P)M(κ²-2-C₆F₄PPh₂)(µ-2-C₆F₄PPh₂)M’Cl]x (x = 1: 6MM’; M = Pt; M’ = Cu, Au; x = 2: 6PtAg), head-to-tail-[(Me₃P)ClM(µ-2-C₆F₄PPh₂)₂M’] (7MM’; M = Ni, Pt; M’ = Au) and head-to-head-[(Me₃P)ClM(µ-2-C₆F₄PPh₂)₂M’] (8MM’; M = Ni, Pt; M’ = Cu, Ag, Au) were observed. Single crystal X-ray analyses of complexes 5-8 reveal short metal-metal separations (2.7124(3) – 3.3287(7) Å) suggestive of attractive metal-metal interactions. Quantum chemical calculations (AIM, ELF, NCI, NBO) gave theoretical support that the interaction characteristics reach from pure attractive non-covalent to electron-shared (covalent) character.