A route to small clusters: a twisted half-hexagram-shaped M(OH) cluster and its capacity for hosting closed-shell metals.

By combining different oxidation states, coordination indices and bridging systems, it has been possible to obtain the structurally novel M(OH) cluster core (M = transition metal) found in the organometallic compound (NBu)[PtPt(CCl)(μ-OH)(μ-OH)] (1). The cluster is formed by two (μ-OH) and two (μ-OH) units that bond platinum atoms in different oxidation states. The cluster core geometry can best be described as a half-hexagram. Compound 1 is an excellent precursor for preparing heterometallic clusters since it can host d or s Lewis-acid metal centers through Pt→M dative bonds, as demonstrated by its reaction with Ag(i) to produce the heterometallic [AgPtPt(CCl)(μ-OH)(μ-OH)] (2), which has four unbridged Pt-Ag bonds.