Four highly soluble square-planar Cu(II) and Ni(II) complexes of siloxy-salens (2SiCu, 2SiNi) and hydroxy-salens (2Cu, 2Ni) have been synthesized. An X-ray crystal structure analysis was performed on 2SiCu, 2SiNi, and 2Ni. The compounds have been investigated by cyclic voltammetry, UV-vis-NIR spectroelectrochemistry, and EPR spectroscopy. According to these results, the monooxidized species [2SiCu]+ and [2SiNi]+ are to be classified as Robin-Day class II and III systems, respectively. Magnetic measurements on the dinuclear (PMDTA)Cu(II) complex 1Cu2 x (PF6)2 with deprotonated 1,4-dihydroxy-2,5-bis(pyrazol-1-yl)-benzene (1) linker revealed antiferromagnetic coupling between the two Cu(II) ions thereby resulting in an isolated dimer compound. Coordination polymers [1Cu]n(H2O)(2n) of Cu(II) ions and bridging p-hydroquinone linkers were obtained from CuSO4 x 5 H2O and 1,4-dihydroxy-2,5-bis(pyrazol-1-yl)benzene. X-ray crystallography revealed linear chains running along the crystallographic a-direction and stacked along the b-axis. Within these chains, the Cu(II) ions are coordinated by two pyrazolyl nitrogen atoms and two p-hydroquinone oxygen atoms in a square-planar fashion.

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The first ansa-nickelocenes, [Ni(η 5 ,η 5 -C 5 H 4 -CH 2 -CHdCH-CH 2 -C 5 H 4 )] ( 4) and [Ni(η 5 ,η 5 -C 5 H 4 - 6), were prepared by alkene metathesis of 1,1′-disubstituted nickelocenes. Compound 4 reacts with hydrogen to yield ansa-nickelocene 7, bearing the saturated bridge. The new compounds were characterized by UV-vis, IR, MS, 1 H NMR, magnetic susceptibility, and electrochemical measurements. Crystal and molecular structures of 4, 6, and 7 were determined by single-crystal X-ray analysis. These measurements show that the studied ansa-nickelocenes exhibit properties similar to those of nickelocene.