Synthesis of Metallostannylenes from Transition Metal Polyhydride Complexes

Syntheses of high-valent open-chain metallostannylene hydride complexes from transition metal polyhydride complexes and aryl-substituted amidostannylenes are reported. The reaction of (^MeBDI^Dipp)IrH₄ (^MeBDI^Dipp = (Dipp)NC(Me)CH(Me)CN(Dipp); Dipp = 2,6-diisopropylphenyl) with DMPSnN(SiMe₃)₂ (DMP = C₆H₃-2,6-Mes₂, Mes = mesityl) gives access to metallostannylene (^MeBDI^Dipp)IrH₃SnDMP (1) with HN(SiMe₃)₂ as the byproduct. Similarly, treatment of Cp*IrH₄ (Cp* = η⁵-C₅Me₅) with DMPSnN(SiMe₃)₂ leads to the formation of Cp*IrH₃SnDMP (2). In contrast to 1, 2 cleanly reacts with a second equivalent of DMPSnN(SiMe₃)₂, allowing for the synthesis of bis(metallostannylene) Cp*IrH₂(SnDMP)₂ (3). Additionally, the synthesis and characterization of two new amidostannylenes DMPSn[N(Dipp)(SiMe₃)] (4) and TripSn[N(Dipp)(SiMe₃)] (5; Trip = 2,4,6-triisopropylphenyl) is presented. While the reaction of Cp*IrH₄ with 4 represents an alternative route to 2, treatment of (^MeBDI^Dipp)IrH₄ with 5 yields the amidostannylene complex (^MeBDI^Dipp)(H)₂Ir═Sn(Trip){N(Dipp)(SiMe₃)} (6) with concomitant release of H₂, rendering stannylene coordination a reaction pathway that competes with Sn-N bond cleavage and metallostannylene formation. Within the broader context of transition metal-main group element compounds, metallostannylene formation is characterized as a formal deprotonation of the transition metal polyhydride complex by the amidostannylene. Notably, the ambiphilicity of amidostannylenes, which distinguishes them from tetravalent amidostannanes, appears to be essential for efficient Ir-Sn bond formation.