Synthesis and crystal structures of [Sn{2-[(Me3Si)2C]C5H4N}R] [R = C6H2Pri3,4,6 1 or CH(PPh2)2 2], two novel heteroleptic tin(II) compounds derived from [Sn-{2-[(Me3Si)2C]C5H4N}Cl], and for [{Sn(C6H2Pri3-2,4,6)2}3] 3, a structural redetermination

Two novel, monomeric heteroleptic tin(II) derivatives, [Sn{2-[(Me3Si)(2)C]C5H4N}R] [R = C6H2Pr3i,-2,4,6 1 or CH(PPh2)(2) 2], have been prepared, characterised by multinuclear NMR spectroscopies and their molecular structures determined by single crystal X-ray diffraction. Both compounds were prepared from the corresponding heteroleptic tin(II) chloro-analogue, [Sn{2-[(Me3Si)(2)C]C5H4N}Cl], and thus demonstrate the utility of this compound as a precursor to further examples of heteroleptic tin(II) derivatives: such compounds are often unstable with respect to ligand redistribution. In each case, the central tin(II) is three-co-ordinate, Crystals of trimeric [{Sn(C6H2Pr3i-2,4,6)(2)}(3)] 3 were found to undergo a solid state phase transition, which may be ascribed to ordering of the ligand isopropyl groups. At 220 K the unit cell is orthorhombic, space group Pna2(1), compared with monoclinic, space group P2(1)/c, for the same crystals at 298 K, in which there is an effective tripling of the now b (originally c) axis. This result illustrates the extreme crowding generated by this bulky aryl ligand.