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

A series of related mono anddouble bridged heterobimetallicd(8)-d(10) complexes with a [MM '](3+) core (M = Ni, Pt; M ' = Cu, Ag, Au) have been synthesized.Dependent on the synthesis strategy, a variety of isomers of the composition[(Me3P)( x )M-(2-C6F4PPh2)(2)M ' Cl] (x = 1, 2) was isolated. All synthesized compounds feature short metal-metalseparations (2.7124(3)-3.3287(7) angstrom). Metallophilic bondingtrends were discussed along the isomeric series using DFT analysis(NCI, ELF, NBO). Treatment of the bis-(chelate) complexes trans-[M-(kappa(2)-2-C6F4PPh2)(2)](trans-1M; M = Ni, Pt) and cis-[Pt-(kappa(2)-2-C6F4PPh2)(2)] (cis-1Pt) with equimolaramounts or excess of PMe3 solution gave complexes of thetype [(Me3P)( x )M-(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 toward monovalent coinage metal ions (M ' = Cu, Ag,Au) was investigated next to the reaction of 1M toward[AuCl-(PMe3)]. Four different complex types [(Me3P)(2)M-(mu-2-C6F4PPh2)(2)M ' Cl] (5MM '; M = Ni, Pt;M ' = Cu, Ag, Au), [(Me3P)-M-(kappa(2)-2-C6F4PPh2)-(mu-2-C6F4PPh2)-M ' Cl]( x ) (x = 1: 6MM '; M = Pt; M ' = Cu,Au; x = 2: 6PtAg), head-to-tail-[(Me3P)-ClM-(mu-2-C6F4PPh2)(2)M '] (7MM '; M = Ni, Pt; M '= Au), and head-to-head-[(Me3P)-ClM-(mu-2-C6F4PPh2)(2)M '] (8MM '; M = Ni, Pt; M ' = Cu, Ag, Au) were observed. Single-crystalX-ray analyses of complexes 5-8 revealedshort metal-metal separations (2.7124(3)-3.3287(7) angstrom),suggestive of attractive metal-metal interactions. Quantumchemical calculations (atoms in molecules (AIM), electron localizationfunction (ELF), non-covalent interaction (NCI), and natural bond orbital(NBO)) gave theoretical support that the interaction characteristicsreach from a pure attractive non-covalent to an electron-shared (covalent)character.