Syntheses, Structures And Properties Of Coordination Complexes Supported By Schiff Base Ligands

The syntheses and magnetic properties of coordination complexes supported bySchiff base ligands were reported. Twenty-two coordination complexes weresynthesized by reactions of transition metal ions as well as rare-earth metal ions withSchiff base ligands. The magnetic properties of four complexes were investigated. Themain results are as follows:Five polynuclear coordination complexes of the compositions[Ni₄{（py）C（H）NO}₄Cl₂（CH₃O）₂]（1）,[Ni₁₀{（py）C（H）NO}₁₂Cl₈]（2）,{[Fe₃{（ph）（2-py）CHO}₄Cl₄]⁺·FeCl₄^-}（3）,[Ni₄{（ph）（2-py）CNO}₄（C₂H₅OH）₄Cl₄]（4）,[Cu₂{（ph）（2-py）CHO}{（ph）（2-py）CNO}Cl₂][C₂H₅OH]（5）, have been hydrothermallysynthesized by using2-pyridinealdoxime （py）C（H）NOH,phenyl-pyridine-2-yl-methanone oxime （ph）（2-py）CNOH as primary ligand,respectively. The complexes were characterized by X-ray single crystal diffraction, IRspectroscopy, and elemental analysis. Variable-temperature magnetic susceptibilities of1,2and3have been measured in the temperature range of2-300K, andanti-ferromagnetic interactions are determined in1,2and3. The most interestingsynthetic features of complex3and5are the in situ transformation of （ph）（2-py）CNOHinto （ph）（2-py）CHO^-, and the possible reaction mechanism was proposed. We alsofound that the complexes with variety structures can be obtained in the presence ofsecond transition metal salts like Zn（OAc）₂·2H₂O or SmCl₃·6H₂O. The functions of thesecond transition metal salts are still unknown now.Six polynuclear coordination complexes of the compositions[Cu^I₂Cu^II₂{NH₂C（CH₂O）（CH₂OH）₂}₄（CH₃COO）₂]（6）,[Co^II₄Co^III₃{NH₂C（CH₂O）₂（CH₂OH）]₆}（NO₃）₄（CH₃OH）₂NO₃]（7）, [Co^II₃Co^III₂（HL₂）₂（H₂L₂）₂（1-naph）（CH₃COO）]（8）,[Co^IICo^III（H₂L₂）₂（CH₃COO）]_n（9）,[Co^II₂Co^III₂（H₂L₂）₄（C₂O₄）]（10） and [Cr₂（H₂L₂）₂（Cl₂）][CH₃OH]（11） have beenhydrothermally synthesized by using2-amino-2-（hydroxymethyl）-propane-1,3-diol（H₃L₁） and （E）-2-（hydroxymethyl）-2-（（（2-hydroxynaphthalen-1-yl）methylene）amino）propane-1,3-diol （H₄L₂） as ligand, respectively. Mixed valence state Cu^I/Cu^IIwas foundin6, and the Co^II/CoIIImoiety was found in7,8,9and10. Variable-temperaturemagnetic susceptibilities of6have been measured in the temperature range of2-300K,and ferromagnetic interactions are found in6.Four novel coordination polymers of the formula [Sm{（ph）（2-py）CNOH}₃（Cl₃）]（12）,[Ln₄{（ph）（2-py）CNO}₆（NO₃）₄（OH）₂]（Ln=Er（13）, Gd（14）, Dy（15））, have beenhydrothermally synthesized by using phenyl-pyridine-2-yl-methanone oxime（ph）（2-py）CNOH as primary ligand. X-ray single crystal diffraction, IR spectroscopy,and elemental analysis showed that12is a single-core complex,13-15are tetra-nuclearcomplexes. Complexes13-15are isostructral and isomorphous. There are two differentcoordination environments for each metal center, one is eight coordinated, the other isnine coordinated. Lanthanide contraction was observed for these complexes.Seven novel coordination polymers of the compositions[La（H₂napn）（SCN）（C₂H₅OH）₂（NO₃）₂]_n（16）,[La（H₂napn）₂（SCN）（NO₃）₂]_n（17）,[Ln（H₂napn）_1.5（NO₃）₃]_n（Ln=La（18）, Sm（19）, Nd（20）, Er（21）, Eu（22））, have beenhydrothermally synthesized by using versatile ligand H2napn（N,N’-ethylenebis（2-hydroxy-1-naphthylideneiminato））. Complexes16-17wereobtained by using the same reactants at different ratio, and exhibit1D chain and2D netstructure, respectively. Complexes18-22exhibit the same2D net structures. All metalcenter displays nine coordinate environment. Lanthanide contraction was shown forthese complexes.