Studies On New Types Of Dithiolate And Diimine Transition Metal Coordination Compounds

Dithiolate metal coordination compounds are one important studying object of new functional complexes in the frontier of inorganic chemistry field. For theoretical and practical meanings, it is important to synthesize new dithiolate metal complexes with new structure and function, investigate the relationship between the structure and the property of resulted compounds.This dissertation concerns with the synthesis, characterization, structure, property and theoretical analysis of new functional complexes, derived from ligand maleonitriledithiolate (mnt²), l,3-dithiole-2-thione-4,5-dithiolate (dmit²-), and α,α'-diimine (2,2'-bipyridine, 4,4'-di-methyl-2,2'-bipyridine, 1,10-phenanthroline). In this work, fifteen novel coordination compounds were designed and synthesized; the crystal and molecular structures of nine of them were solved and refined. Based on the experimental and theoretical computing results, some relationships between the structures and properties of some compounds were investigated.1. Four novel coordination compounds containing both dmit²- and α,α'-diimine were synthesized and characterized: two neutral mononuclear complexes [Ni(dmit)(bipy)2] and [Ni(dmit)(phen)₂], one neutral binuclear complex [Zn(dmit)(phen)]₂, and one ion-pair charge-transfer type complex [Zn(phen)₃][Zn(dmit)2], the later three of them were also characterized by X-ray crystallography. In the given conditions, the neutral mixed-ligand complexes could be synthesized through the ligand-exchanging reaction between the cationic and anionic complexes containing ether the same or different metal ionic, and the ion-pair charge-transfer type complex, which containing one kind of ligands in the cation and the other kind of ones in the anion, could be prepared by ligand-replacing reaction. For complex [Ni(dmit)(phen)₂], [Zn(dmit)(phen)]2 and [Zn(phen)₃][Zn(dmit)₂], it is shown that there are n-n packing interactions among their molecules in the crystals, and the interactions are strongest for the last one. Furthermore, dmit in [Ni(dmit)(phen)2] is coordinated to metal in a bent model, and one sulphur atom of every dmit in [Zn(dmit)(phen)]₂ behaves as a bi-bridge coordination atom, hence it is coordinated with both zinc atoms. For complex [Zn(phen)₃][Zn(dmit)2], stronger S-S intermolecular interactions were observed. In visible region, medium intense LL'CT bands were observed in solution for the three neutral mixed-ligand complexes, and both LMCT band and IPCT band were observed for [Zn(phen)₃][Zn(dmit)₂]. In DMF and MeCN medium, all of the four complexes possess some intense fluorescence emitting in the region of 360 — 500 nm on the exciting of UV. From the results of various spectral studies, tt is also found that there are interactions between ionic [Zn(dmit)₂]²- and [Zn(phen)₃]²+ in solution.2. Three novel charge-transfer type coordination compounds (EV)₂[M(mnt)₂] (M = Ni, Cu, Zn) derived from bis(maleonitriledithiolate)transition-metal coordination anions and ethyl violet cation (EV), were synthesized and characterized. Their crystals were obtained and the crystal structure of the complexes containing nickel and copper were solved and refined. The two complexes belong to isomorphism. It is found that both them crystallized in P-\ space group and possess columnar stacking structure. No intermolecular interaction was observed between the anions. The cationic ion EV has triangular plane geometry with a propeller conformation and the whole molecule only has an A symmetry, not the expected D₃. Through point contact interactions, adjacent cationic ions form a pseudo-dimmer, which contacts with the anions by weak H-bond contacts. At room temperature, only thecharacteristic adsorption bands and fluorescence emitting bands belonging to EV could be observed in visible region for anyone of the solutions of three complexes, the bands of anionic [M(mnt)2]2 should be overlapped. It is noted that [M(mnt)2]2 have the fluorescence bands of EV shift a little to red region. For theoretical and practical meanings, it is valuable to study on the spectroscopic properties of this kind of compounds.3. Six novel ion-pair charge-transfer type complexes, containing bis(maleonitriledithiolate)-transition-metal coordination anions and tris(a,a'-diimine)metal coordination cations, were synthesized and characterized: two homo-nuclear complex [Ni(dmbpy)3][Ni(mnt)2] and [Zn(phen)3][Zn(mnt)2], four hetero-nuclear [Ni(phen)3][Cu(mnt)2], [Ni(bipy)3][Cu(mnt)2], [Ni(phen)3][Pt(mnt)2] and [Ni(bipy)3][Pt(mnt)2]. For complex [Ni(dmbpy)3][Ni(mnt)2] and [Ni(bipy)3][Pt(mnt)2], their crystal structures have been measured and refined. In the given conditions, it is found that this kind of mnt-metal and diimine-metal ion-pair charge-transfer type complexes could be easily prepared through metathesis, ligand-exchanging and ligand-replacing reaction. The crystals for all of the six complexes could be obtained in experimental conditions, but all those containing coordinated phen are not stable. The three complexes left containing coordinated bipy or dmbpy all crystallized in monoclinic but with different space groups. In their crystals, electrostatic force is the main intermolecular interaction for these complexes. In visible region, medium intense LMCT bands were observed in solution for these complexes. In DMF and MeCN medium, all of the six complexes possess certain intense fluorescence emitting in the region of 300 — 500 nm on the exciting of UV. The central metal bonded by diimine, coordination anion and solvent have apparent effects on the fluorescence of the diimines.4. A new kind of mixed-valence dithiolae-metal and diimine-metal ion-pair charge-transfer type complexes [Ni(phen)3]2[Ni(mnt)2]3 and [Ni(phen)3]2[Pt(mnt)2]3 were synthesized and characterized, their crystal structures have been measured and refined. In process of preparating these complexes through metathesis reaction, the addition of counter ion [Ni(phen)3]2+ may induce the disproportionation of [M(mnt)2] (M = Ni, Pt), making two kind of anion [M(mnt)2] and [M(mnt)2]2" occur simultaneously in the obtained complexes. The two complexes belong to isomorphism; variation of central metal in the anions has no important effect on the pacing model. In the crystals, the anion [M(mnt)2] and [M(mnt)2] are separated each other; there are n-n packing interactions among [M(mnt)2] themselves and among [M(mnt)2] and the counter ions, meanwhile [M(mnt)2]2 only interacts with the counter ions through point-contact interactions. In visible region, medium intense LMCT and L(;r)MCT bands were observed in solution for the complexes. In DMF and MeCN medium, the complexes possess certain intense fluorescence emitting in the region of 400 — 550 nm on the exciting of UV. Solvent has apparent effects on the fluorescence of the compounds. From the fluorescence spectra, it is also found that there are interactions between ionic [M(mnt)2] and [Ni(phen)3]2+ in solution.5. The molecular geometry, bonding and electronic structure, and vibration spectrum of [Ni(dmit)(phen)2] have been studied by DFT method, and the molecular geometries of [Zn(dmit)(phen)]2, [Zn(dmit)(bipy)]2, and hypothetical complex [Zn(mnt)(phen)]2 and [Zn(mnt)(bipy)]2 have been studied by PM3 methods. It has been found that the [Ni(dmit)(phen)2] is of planar structure with the symmetry of C2, and the ground state is of triplet state. In free molecule state, nickel atom and the ligand dmit are coplanar; C=S of coordinated dmit has only one normal vibration model, corresponding to the intense bandaround 1051cm ' observed in experiment. Another observed intense band around 1030 cm"1 is also related to the normal vibration model of C=S, Fermi resonance caused by the vibration of C=S with the overtone of ^S(S2C=S) may have important contribution, and the other groups such as C=C may also have their contributions. For [Zn(mnt)(phen)]2 and its homologues, they have simlar geometric structure with Q symmetry. It is found that they all possess planar S2ZnlS2aZnla four-member cycle structure, and the bond length of S2-Znl in mono-molecule [Zn(S-S)(N-N)] is longer than that of the intermolecular S2-Znlabond.