Diiridium complexes with µ2-Sn ligands in different binding modes.

The synthesis and characterization of the µ2-stannide complex [(MeBDIDipp)IrH2]2(µ-Sn) (1; MeBDIDipp = (Dipp)NC(Me)CH(Me)CN(Dipp), Dipp = 2,6-diisopropylphenyl) and the closely related dimetallostannylene [(MeBDIDipp)IrH3]2(µ-Sn) (2) are reported. While 1 is accessible from (MeBDIDipp)IrH4 and Sn[N(SiMe3)2]2, salt metathesis of (MeBDIDipp)IrH3Li with SnCl2 allows for the preparation of 2. Also, treatment of 1 with H2 leads to 2 in addition to side products, thus representing a rare example of a formal 1,3-addition to a heavy allene analogue and a switch in binding mode of a µ2-tetrylide ligand. A comprehensive mechanistic picture for the formation of the new complexes 1 and 2 is presented, which also takes the previously reported cyclic dimetallostannylenes [(MeBDIDipp)IrH2(µ-Sn)]n (n = 2, 3) into account. Essentially, the syntheses are assumed to proceed via an elusive amido(metallo)stannylene intermediate, (MeBDIDipp)IrH3SnN(SiMe3)2 (INT1); a more stable derivative of INT1, (MeBDIDipp)IrH3SnN(Dipp)(SiMe3) (3), was observed by 1H NMR spectroscopy when (MeBDIDipp)IrH4 was treated with Sn[N(Dipp)(SiMe3)]2.