Methoxy-Substituted Transition Metal β-Diketonates: Synthesis and Properties

Novel volatile complexes of Ni(II), Co(II), Mn(II), Zn(II) with methoxy-substituted β-diketonate ligands L = (CH₃)₂C(OCH₃)-CO-CH-CO-C(CH₃)₃ and L^F = (CH₃)₂C(OCH₃)-CO-CH-CO-CF₃ are obtained. The novel compounds are identified by a complex of techniques, including CHF elemental, mass spectrometric, and NMR spectroscopic analyses. According to the X-ray crystallographic analysis data, in the crystals, NiL₂ and ZnL₂ are asymmetric binuclear complexes in which metal atoms have a different coordination environment composed of ligand oxygen atoms (c.n.= 6 and 5) and are bridged by oxygen atoms, both chelate and from one of the methoxy groups. The mixed-ligand complex [NiL(dpm)]₂ (dpm = dipivaloylmethanate: 2,2,6,6-tetramethyl-3,5-heptandionate) has a similar binuclear structure. It is found that complexes with non-fluorinated ligands pass to the gas phase as monomers whereas fluorine-containing complexes pass as dimers. The compounds are paramagnetic, except zinc complexes. In the binuclear complexes based on non-fluorinated ligands, a ferromagnetic exchange interaction of magnetic moments is observed while for fluorine-containing ligands it is antiferromagnetic.