Chemistry of a novel family of tridentate alkoxy tin(II) clusters

The chemical interconversions observed for a novel family of trihydroxymethyl ethane (THME-H-3) ligated Sn(II) compounds have been determined using single-crystal X-ray and Sn-119 NMR experiments. (mu-THME)(2)Sn-3 (1) was isolated from the reaction of 3 equiv of [Sn(NR2)(2)](2) (R = SiMe3) with 4 equiv of THME as a unique trinuclear species capped above and below the plane of Sri atoms by two THME ligands. Upon reaction with "Sn(NR2)(2)", compound 1 rearranged to yield another novel molecule [(mu-THME)Sn2-(NR2)](2) (2). Compound 2 could also be formed directly from the stoichiometric mixture of THME-H-3 and [Sn(NR2)(2)](2). Further studies revealed that I would also rearrange in the presence of Sn(OR)(2) to form [(mu-THME)Sn-2(mu-OR)](2) [OR = OMe (3), OCH2Me (4), OCH2CH(Me)CH2CH3 (5), OCH2CMe3 (6, ONep), OC6H5 (7, not structurally characterized), OC6H4Me-3 (8), OC6H4Me-2 (9), OC6H3(Me)(2)-2,6 (10), OC6H3(CHMe2)(2)-2,6 (11). Additionally, 3-11 could by synthesized from the reaction of 2 and the appropriate H-OR. Sn-119 solution NMR studies of 2-11, in THF-d(8) indicate that an equilibrium between the parent complex and its disassociation products (1 and the free parent Sn alkoxy or amide precursor) exists at room temperature. This is a likely reason behind the ease of interconversion observed for 1. The generality of this exchange was further verified through the reaction of 1 with [Ti(mu-ONep)(ONeP)(3)](2), which led to the isolation of (mu- ONeP)(2)Sn-3(mu-THME)(2)Ti(ONeP)(2) (12). For 12, the solid-state structure was maintained in solution with no indication of an equilibrium.