Synthesis of Mixed Tin–Ruthenium and Tin–Germanium–Ruthenium Carbonyl Clusters from [Ru3(CO)12] and Diaminometalenes (M = Sn, Ge)

Diaminostannylenes react with [Ru3(CO)12] without cluster fragmentation to give carbonyl substitution products regardless of the steric demand of the diaminostannylene reagent. Thus, the Sn3Ru3 clusters [Ru3{μ-Sn­(NCH2tBu)2C6H4}3(CO)9] (4) and [Ru3{μ-Sn­(HMDS)2}3(CO)9] (6) [HMDS = N­(SiMe3)2] have been prepared in good yields by treating [Ru3(CO)12] with an excess of the cyclic 1,3-bis­(neo-pentyl)-2-stannabenzimidazol-2-ylidene and the acyclic and bulkier Sn­(HMDS)2, respectively, in toluene at 110 °C. The use of smaller amounts of Sn­(HMDS)2 (Sn/Ru3 ratio = 2.5) in toluene at 80 °C afforded the Sn2Ru3 derivative [Ru3{μ-Sn­(HMDS)2}2(μ-CO)­(CO)9] (5). Compounds 5 and 6 represent the first structurally characterized diaminostannylene-ruthenium complexes. While a further treatment of 5 with Ge­(HMDS)2 led to a mixture of uncharacterized compounds, a similar treatment with the sterically alleviated diaminogermylene Ge­(NCH2tBu)2C6H4 provided [Ru3{μ-Sn­(HMDS)2}2{μ-Ge­(NCH2tBu)2C6H4}­(CO)9] (7), which is a unique example of Sn2GeRu3 cluster. All these reactions, coupled to a previous observation that [Ru3(CO)12] reacts with excess of Ge­(HMDS)2 to give the mononuclear complex [Ru­{Ge­(HMDS)2}2(CO)3] but triruthenium products with less bulky diaminogermylenes, indicate that, for reactions of [Ru3(CO)12] with diaminometalenes, both the volume of the diaminometalene and the size of its donor atom (Ge or Sn) are of key importance in determining the nuclearity of the final products.