Two novel coordination compounds, [Zn(L) 2 (OOCH) 2 ] (1) and [Zn(L) 3 (OCHO)](OCHO)]•H 2 O (2) (where L = 2-isopropylimidazole, C 6 H 10 N 2) have been prepared by reaction of 2-isopropylimidazole with zinc(II) formate at room temperature using toluene as solvent. These compounds were characterized by elemental and thermal analyses, IR, 1 HNMR and 13 CNMR spectroscopies, single crystal X-ray diffraction and DFT studies. The Zn centers in 1 and 2 adopt pseudo-tetrahedral coordination geometries. Compound 1 crystallizes in the monoclinic system P2/c space group whereas compound 2 crystallizes in the P-1 space group of the triclinic crystal system. Several types of hydrogen intra-/intermolecular interactions are observed in these materials and extend into a two-dimensional leaf like network in 1 and a two-dimensional lattice of rectilinear pillars in 2. Compounds 1 and 2 were also optimized and their frontier molecular orbitals, global reactivity descriptors, molecular electrostatic potential, natural bond orbitals were investigated using density functional theory (DFT). In fact the induced structural differences from complex 1 to complex 2 led to the reduction of the frontier molecular orbital energy gap by 1.338 eV and a decrease of the chemical hardness by 0.669 eV.

The reaction of benzene-1,2,3-tricarboxylate copper(II) trihydrate (Cu 3 (1,2,3-BTC) 2 •3H 2 O) and ethylenediamine (en) gave after recrystallization from methanol at room temperature violet crystalline solid of the polymeric two dimensional material {[Cu 3 (μ 3 -1,2,3-BTC)(μ 2 -1,2,3-BTC)(en) 3 (OH 2 ) 2 (OH)(μ 2 -OH 2 )] 2 •5H 2 O•O} n (1) as identified by single crystal X-ray diffraction analysis. The compound was also characterized by elemental analysis, FT-IR spectroscopy, UV-vis spectroscopy, thermogravimetric analysis (TGA) and magnetic susceptibility. The molecular structure indicates crystallization in the triclinic space group P-1 with the unit cell parameters a = 12.1205(3) Å, b = 12.7026(3) Å, c = 13.9890(3) Å, α = 75.034(1)˚, β = 74.957(1)˚, γ = 68.415(1)˚. Structural analysis also revealed that the dimeric compound is connected by Cu-O-Cu bridges and the dimer is further converted into a polymeric chain structure through bridging of one benzene-1,2,3-tricarboxylate ligand. Different coordination modes are observed at the copper atom. The Cu atom at the center is octahedral while the two other ones are pentacoordinated. Thermal analysis of the compound showed decomposition processes, while magnetic studies indicated a magnetic susceptibility μ of 3.21 BM.

Two novel copper complexes (1,2) with N,O-donor ligands were synthesized by reaction of copper(II) malonates with 3,3'-bis(pyrazolyl)pentane and 4,4'-trimethylenedipyridine in methanol at moderate temperature. These compounds were characterized by elemental analysis, UV-VIS, IR spectroscopies and powder X-ray diffraction analyses. Compound (1) melts at higher temperature (202˚C) than compound (2) (100˚C). The IR spectra showed typical vibrations related to C=N and C=C, characteristic of pyrazolyl and pyridine ligands.

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