[Pd₄(μ₃-SbMe₃)₄(SbMe₃)₄]: A Pd(0) Tetrahedron with μ₃-Bridging Trimethylantimony Ligands

Abstract

The palladium(II) chlorostibine complex [PdCl2(SbMe2Cl)2]2 has a dimeric structure in the solid state, stabilized by hyper-coordination at the Lewis amphoteric Sb centers. Reaction with 8 equiv of MeLi forms [Pd4(μ3-SbMe3)4(SbMe3)4], whose structure comprises a tetrahedral Pd(0) core with four terminal SbMe3 ligands and four μ3-SbMe3 ligands, one capping each triangular Pd3 face. Density functional theory calculations, supported by energy decomposition analysis and the natural orbitals for chemical valence scheme, highlight significant donor and acceptor orbital contributions to the bonding between both the terminal and the bridging SbMe3 ligands and the Pd4 core.

A Five-Membered PdSbn Coordination Series

“…Comparison of the bond lengths and angles show them to be essentially chemically identical, with the largest variation being a spread of 0.17 Å in the Sb•••ClPd distances (Table S7). As previously reported, 17 combination of the same two reagents in a 2:1 Sb:Pd ratio gives the red dimer [Pd 2 Cl 4 (SbMe 2 Cl) 4 ] (2). Recrystallisation of this complex from benzene or dichloromethane results in the formation of the respective solvates, 2•4C 6 H 6 and 2•2CH 2 Cl 2 ( Figure 3) whose solid-state structures both contain centrosymmetric dimeric units similar to that found in the unsolvated complex.…”

“…We have previously reported one of the first examples of a halostibine complex with a transition metal halide, [Pd 2 Cl 4 (SbMe 2 Cl) 4 ] (2, Figure 1b), a dimer in the solid-state with two eclipsing square planes held together by secondary ClSb interactions. 17 Reaction of this complex with MeLi results in the formation of the Pd(0) tetramer [Pd 4 (SbMe 3 ) 8 ], an unprecedented example of µ 3bridging by a pnictine ligand (Figure 1b). 17 Here we report an unusual coordination series of five complexes with the general formula PdCl 2 (SbMe 2 Cl) n (n = 1-5), of which 2 is one member (n=2), formed by reacting the same ligand and metal precursor in five different molar ratios.…”

“…17 Reaction of this complex with MeLi results in the formation of the Pd(0) tetramer [Pd 4 (SbMe 3 ) 8 ], an unprecedented example of µ 3bridging by a pnictine ligand (Figure 1b). 17 Here we report an unusual coordination series of five complexes with the general formula PdCl 2 (SbMe 2 Cl) n (n = 1-5), of which 2 is one member (n=2), formed by reacting the same ligand and metal precursor in five different molar ratios. All show Lewis amphoterism of the Sb centres, with either intra-or intermolecular secondary interactions which direct their solid-state structures, leading in four cases to supramolecular architectures.…”

“…We have previously reported one of the first examples of a halostibine complex with a transition metal halide, [Pd 2 Cl 4 (SbMe 2 Cl) 4 ] (2, Figure 1b), a dimer in the solid state with two eclipsing square planes held together by secondary Cl→Sb interactions. 17 Reaction of this complex with MeLi results in the formation of the Pd(0) tetramer [Pd 4 (SbMe 3 ) 8 ], an unprecedented example of μ 3 -bridging by a pnictine ligand (Figure 1b).…”

Synthesis, properties and structures of gallium(III) and indium(III) halide complexes with neutral pnictine coordination

“…After many years of relative neglect, the coordination chemistry of transition metal stibine (SbR3) complexes has received much more detailed attention in the last twenty-five years, revealing significant differences to the much-studied phosphine and arsine analogues [1,2]. Notable features of stibines include their ability to behave as bridging ligands between two metal centres [3,4] and their tendency to generate hypervalent coordination, where a stibine functioning as a σ-donor to a metal centre, simultaneously behaves as a σ-acceptor towards another donor group, including halide, amine, ether, triflate, etc. [5].…”