Metallacycles of Iron, Zinc, and Cadmium Assembled by Polytopic Bis(pyrazolyl)methane Ligands and Fluoride Abstraction from BF4

Reactions of the arene-linked bis(pyrazolyl)methane ligands m-bis[bis(1-pyrazolyl)methyl]benzene (m-[CH(pz)2]2C6H4, L m ) and 1,3,5-tris[bis(1-pyrazolyl)methyl]benzene (1,3,5-[CH(pz)2]3C6H3, L 3 ) with BF4 - salts of divalent iron, zinc, and cadmium result in fluoride abstraction from BF4 - and formation of fluoride-bridged metallacyclic complexes. Treatment of Fe(BF4)2·6H2O and Zn(BF4)2·5H2O with L m leads to the complexes [Fe2(μ-F)(μ-L m )2](BF4)3 (1) and [Zn2(μ-F)(μ-L m )2](BF4)3 (2), in which a single fluoride ligand and two L m molecules bridge the two metal centers. The reaction of [Cd2(thf)5](BF4)4 with L m results in the complex [Cd2(μ-F)2(μ-L m )2](BF4)2 (3), which contains dimeric cations in which two fluoride and two L m ligands bridge the cadmium centers. Equimolar amounts of the tritopic ligand L 3 and Zn(BF4)2·5H2O react to give the related monofluoride-bridged complex [Zn2(μ-F)(μ-L 3 )2](BF4)3 (4), in which one bis(pyrazolyl)methane unit on each ligand remains unbound. NMR spectroscopic studies show that in acetonitrile the zinc metallacycles observed in the solid-state remain intact in solution.