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New urea-coordinated dinickel(II) complexes with binucleating ligands— HL 1 , which contains dimethylaminoethyl arms, and its analogs HL 2 , which features bis(methoxyethyl) arms, and HL 3 , which contains one dimethylaminoethyl arm and one bis(methoxyethyl) arm—all of which contain a 2-hydroxytrimethylene bridge between the two chelating sites, were synthesized. The structures of [Ni 2 L 1 (μ-CH 3 COO)(CH 3 COO)(urea)(EtOH)]BPh 4 ·EtOH ( 2 ), [Ni 2 L 1 (μ-Cl) 2 (urea)(CH 3 CN)]BPh 4 ·H 2 O ( 3 ), [Ni 2 L 2 (H 2 O) 2 (urea)Cl](BPh 4 ) 2 ·H 2 O ( 5 ), and [Ni 2 L 3 (μ-CH 3 COO) 2 (urea)]BPh 4 ( 7 ) were revealed by X-ray crystallography, as well as those of their parent dinickel(II) complexes, [Ni 2 L 1 (μ-CH 3 COO)(CH 3 COO)(H 2 O) 2 ]BPh 4 ( 1 ), [Ni 2 L 2 (μ-CH 3 COO) 2 ]BPh 4 ·CH 3 CN ( 4 ), and [Ni 2 L 3 (μ-CH 3 COO)(CH 3 COO)(EtOH)]BPh 4 ( 6 ). One urea molecule was coordinated to one dinuclear nickel(II) ion, forming intramolecular hydrogen bonds with a μ-acetato bridge ( 2 , 7 ), a μ-chloro bridge ( 3 ), and coordinated chloro and aqua ligands ( 5 ). The formation of 7 from the reaction of 6 with urea was associated with a change in coordination mode from a non-bridging acetato ligand to a μ-acetato ligand. Magnetic measurements revealed a weak antiferromagnetic interaction between the two nickel(II) ions in 1 ( J = −16.7 cm −1 ) and 2 ( J = −15.0 cm −1 ). |
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