Oxidative Addition Versus Substitution Reactions of Group 14 Dialkylamino Metalylenes with Pentafluoropyridine

Dialkylamino compounds of group 14 elements (Si, Ge,
Sn) in the +2 oxidation state supported by benzamidinate ligands were
synthesized and treated with pentafluoropyridine. Two different modes
of reactivity were observed, depending on the metal atom and the basicity
of the substituent at the metal. Pentafluoropyridine undergoes oxidative
addition reaction at the Si­(II) and Ge­(II) atoms whereas at the Sn­(II)
atom substitution of the NMe2 group by the para fluorine
of pentafluoropyridine occurs. The C–F bond activation by the
lone pair of germanium is the first report of this kind. The Sn­(II)
fluoride obtained has an elongated Sn–F bond length and can
be used as a good fluorinating agent. The compounds were characterized
by multinuclear NMR spectroscopy, mass spectrometry, elemental analysis,
and X-ray structural analysis. Single crystal X-ray structural analysis
of the tin fluoride shows an asymmetric dimer with weak interactions.