Pal Sachindranath, Barik Anil Kumar, Gupta Samik, Hazra Arijit, Kar Susanta Kumar, Peng Shie-Ming, Lee Gene-Hsiang, Butcher Ray J, El Fallah M Salah, Ribas Joan
Department of Chemistry, SreeChaitanya College, Habra, North 24 Parganas, West Bengal, India.
Inorg Chem. 2005 May 30;44(11):3880-9. doi: 10.1021/ic0501420.
A tetranuclear mixed ligand copper(II) complex of a pyrazole containing Schiff base and a hydroxyhexahydropyrimidylpyrazole and copper(II) and nickel(II) complexes of the Schiff base having N-donor atoms have been investigated. A 2 equiv amount of 5-methyl-3-formylpyrazole (MPA) and 2 equiv of 1,3-diamino-2-propanol (1,3-DAP) on reaction with 1 equiv of copper(II) nitrate produce an unusual tetranuclear mixed ligand complex [Cu4(L1)2(L2)2(NO3)2] (1), where H2L1 = 1,3-bis(5-methyl-3-formylpyrazolylmethinimino)propane-2-ol and HL2 = 5-methyl-3-(5-hydroxyhexahydro-2-pyrimidyl)pyrazole. In contrast, a similar reaction with nickel(II) nitrate leads to the formation of a hygroscopic intractable material. On the other hand, the reaction involving 2 equiv of MPA and 1 equiv each of 1,3-DAP and various copper(II) salts gives rise to two types of products, viz. [Cu(T3-porphyrinogen)(H2O)]X2 (X = ClO4, NO3, BF4 (2)) (T3-porphyrinogen = 1,6,11,16-tetraza-5,10,15,20-tetrahydroxy-2,7,12,17-tetramethylporphyrinogen) and [Cu(H2L1)X]X x H2O (X = Cl (3), Br (4)). The same reaction carried out with nickel(II) salts also produces two types of compounds [Ni(H2L1)(H2O)2]X2 [X = ClO4 (5), NO3 (6), BF4 (7)] and [Ni(H2L1)X2] x H2O [X = Cl (8), Br (9)]. Among the above species 1, 3, and 5 are crystallographically characterized. In 1, all four copper atoms are in distorted square pyramidal geometry with N4O chromophore around two terminal copper atoms and N5 chromophore around two inner copper atoms. In 3, the copper atom is also in distorted square pyramidal geometry with N4Cl chromophore. The nickel atom in 5 is in a distorted octahedral geometry with N4O2 chromophore, where the metal atom is slightly pulled toward one of the axial coordinated water molecules. Variable-temperature (300 to 2 K) magnetic susceptibility measurements have been carried out for complex 1. The separations between the metal centers, viz., Cu(1)...Cu(2), Cu(2)...Cu(2)A, and Cu(2)A...Cu(1)A are 3.858, 3.89, and 3.858 A, respectively. The overall magnetic behavior is consistent with strong antiferromagnetic interactions between the spin centers. The exchange coupling constants between Cu(1)...Cu(2) and Cu(2)...Cu(2A) centers have turned out to be -305.3 and -400.7 cm(-1), respectively, resulting in a S = 1/2 ground state. The complexes are further characterized by UV-vis, IR, electron paramagnetic resonance, and electrochemical studies.
对一种含吡唑席夫碱和羟基六氢嘧啶基吡唑的四核混合配体铜（II）配合物以及具有氮供体原子的席夫碱的铜（II）和镍（II）配合物进行了研究。2当量的5-甲基-3-甲酰基吡唑（MPA）和2当量的1,3-二氨基-2-丙醇（1,3-DAP）与1当量的硝酸铜反应生成一种不寻常的四核混合配体配合物[Cu4(L1)2(L2)2(NO3)2]（1），其中H2L1 = 1,3-双（5-甲基-3-甲酰基吡唑基亚甲基亚氨基）丙烷-2-醇，HL2 = 5-甲基-3-（5-羟基六氢-2-嘧啶基）吡唑。相比之下，与硝酸镍的类似反应导致形成一种吸湿性难处理的物质。另一方面，涉及2当量MPA以及各1当量1,3-DAP和各种铜（II）盐的反应产生两种类型的产物，即[Cu(T3-卟啉原)(H2O)]X2（X = ClO4、NO3、BF4（2））（T3-卟啉原 = 1,6,11,16-四氮杂-5,10,15,20-四羟基-2,7,12,17-四甲基卟啉原）和[Cu(H2L1)X]X·H2O（X = Cl（3），Br（4））。用镍（II）盐进行相同反应也产生两种类型的化合物[Ni(H2L1)(H2O)2]X2 [X = ClO4（5），NO3（6），BF4（7）]和[Ni(H2L1)X2]·H2O [X = Cl（8），Br（9）]。在上述物种中，1、3和5通过晶体学进行了表征。在1中，所有四个铜原子均处于扭曲的四方锥几何构型，两个末端铜原子周围有N4O发色团，两个内部铜原子周围有N5发色团。在3中，铜原子也处于具有N4Cl发色团的扭曲四方锥几何构型。5中的镍原子处于具有N4O2发色团的扭曲八面体几何构型，其中金属原子稍微向一个轴向配位水分子拉动。对配合物1进行了变温（300至2 K）磁化率测量。金属中心之间的间距，即Cu(1)...Cu(2)、Cu(2)...Cu(2)A和Cu(2)A...Cu(1)A分别为3.858、3.89和3.858 Å。整体磁行为与自旋中心之间的强反铁磁相互作用一致。Cu(1)...Cu(2)和Cu(2)...Cu(2A)中心之间的交换耦合常数分别为-305.3和-400.7 cm(-1)，导致基态为S = 1/2。通过紫外可见光谱、红外光谱、电子顺磁共振和电化学研究对这些配合物进行了进一步表征。
