Homoleptic tetrakis(silyl) complexes of Pd(0) and Pt(0) featuring metal-centred heterocubane structures: evidence for the existence of the corresponding mononuclear Pd(I) and Pt(I) complexes.

We report on the first homoleptic tetrakis(silyl) complexes of zerovalent Group 10 metals. The compounds [MLi4{Si(3,5-Me2pz)3}4] (M=Pd and Pt; 3,5-Me2 pz=3,5-dimethylpyrazolyl) exhibit very appealing metal-centred heterocubane structures with the central d(10) metal atoms surrounded by four silicon and four lithium atoms. Both compounds were characterised in detail, including X-ray crystal-structure analysis and 2D NMR spectroscopic methods such as (7)Li,(29 Si and (7)Li,(195)Pt HMQC. Cyclic voltammetry studies, in combination with density functional theory (DFT) calculations, revealed that the corresponding mononuclear cationic d(9)-M(I) and dicationic d(8)-M(II) complexes are accessible by stepwise one-electron oxidation of the title compounds. Electron paramagnetic resonance (EPR) investigations provided evidence for the existence of the corresponding paramagnetic palladium(I) and platinum(I) complexes.