Enabling and Probing Oxidative Addition and Reductive Elimination at a Group 14 Metal Center: Cleavage and Functionalization of E–H Bonds by a Bis(boryl)stannylene

By employing strongly σ-donating
boryl ancillary ligands,
the oxidative addition of H2 to a single site SnII system has been achieved for the first time, generating (boryl)2SnH2. Similar chemistry can also be achieved for
protic and hydridic E–H bonds (N–H/O–H, Si–H/B–H,
respectively). In the case of ammonia (and water, albeit more slowly),
E–H oxidative addition can be shown to be followed by reductive
elimination to give an N- (or O-)­borylated product. Thus, in stoichiometric
fashion, redox-based bond cleavage/formation is demonstrated for a
single main group metal center at room temperature. From a mechanistic
viewpoint, a two-step coordination/proton transfer process for N–H
activation is shown to be viable through the isolation of species
of the types Sn­(boryl)2·NH3 and [Sn­(boryl)2(NH2)]− and their onward conversion
to the formal oxidative addition product Sn­(boryl)2(H)­(NH2).