Organozinc Fluoride and Trifluoromethyl Compounds Supported by the Bis(2-pyridylthio)methyl Ligand

The bis­(2-pyridylthio)­methyl ligand, [Bptm], has been
employed
in the synthesis of {[Bptm]­Zn­(μ-F)}2, a rare example
of an organozinc fluoride compound. The dimeric nature of {[Bptm]­Zn­(μ-F)}2, which possesses an uncommon [Zn­(μ-F)]2 motif,
contrasts with the monomeric structures reported for the other halide
derivatives, [Bptm]­ZnX (X = Cl, Br, I); this difference is supported
by density functional theory calculations which indicate that the
fluoride derivative favors a dimeric form with bridging fluoride ligands,
whereas the other derivatives favor monomeric structures with terminal
halide ligands. {[Bptm]Zn(μ-F)}2 reacts
with Me3SiCF3 to afford the organozinc trifluoromethyl
complex, namely [Bptm]­ZnCF3. The Zn–CF3 bond in this complex is longer than the Zn–CH3 bond of the previously reported methyl derivative [Bptm]­ZnMe, an
observation that is precedented in related zinc compounds but counter
to other metal complexes. The infrared frequency corresponding to
the asymmetric C–F stretch of [Bptm]­ZnCF3 is unusually
low for a metal trifluoromethyl species but is comparable to those
for other zinc and cadmium complexes.