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 (MeBDIDipp)IrH4 (MeBDIDipp = (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 (MeBDIDipp)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 (MeBDIDipp)IrH4 with 5 yields the
amidostannylene complex (MeBDIDipp)(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.