| The Mo(W)/S/Cu(Ag) clusters have been extensively investigated due to their rich structural chemistry and potential applications in third-order nonlinear optical (NLO) properties. Among many synthetic routes to such compounds, an efficient one is the employment of the preformed clusters. Precursors containing [MOS3Cux],[MS4Cux] and [(η5-C5Me5)MS3Cux] (x = 14) cores have always been used. However, those containing [Mo2S4M'x] core are less employed. Clusters with [L2Mo2S4] cores exist in several isomer frameworks due to the variety of L and the mode of different S atoms. Some isomer frameworks can be interconvertible. Many such compounds are active in catalyzing the hydrogen addition and desulfurization process. The structure types for such clusters are classified as linear cage-like, incomplete cubane-like and complete cubane-like. In addition, the third-order nonlinear optical (NLO) properties of these clusters have not been explored up to now. In this thesis, several types of clusters were prepared from trans-[(η5-C5Me5)2Mo2(μ-S)2S2], which include a group of halide and pseudo-halide coordinated [Cp*2Mo2S4Cu2] clusters and a group of cubane-like, incomplete cubane-like and gemel-like precursors for the cluster-based assembly. The cubane-like precursors were assembled with a series of bipyridyl and diphosphino ligands, thereby forming several linear polymers and cyclic dimers. The inter-conversion and the third-order NLO properties of some products were also investigated, and the methodology of the construction were discussed.1. The reactions of trans-[(η5-C5Me5)2Mo2(μ-S)2S2] with 2 equiv. of CuX (X = I-, Br-, Cl-, SCN-, CN-) in reflux resulted in the formation of a trans- incomplete cubane-like cluster [(η5-C5Me5)2Mo2(μ3-S)3S(CuI)2] (1), three incomplete cubane-like dimers [(η5-C5Me5)2Mo2(μ3-S)3SCu2Cl(μ-X)]2 ( X = Cl (3), Br (5), SCN (7)) and their cubane-like iosmers [(η5-C5Me5)2Mo2(μ3-S)4(CuX)2] (X = I (2), Cl, Br(4), SCN (6), CN (8)). The trans- incomplete cubane-like frameworks of 1, 3, 5, 7 are unprecedented in the chemistry of [Mo2S4]-based clusters. The trans-to-cis isomerization from 1 to 2 was explored by means of 1H NMR or X-ray powder diffraction, which might take place both in solution and in solid state, and was proved to be irreversible. All products showed excellent third-order NLO absorptions and self-defocusing effects. The third-order NLO performances were remarkably enhanced compared to their precursors, which suggested that the combination of CuX moieties with the [Mo/S] cores might improve their NLO properties.2. As the resulting halide or pseudo-halide coordinated cubane-like clusters didn't react with normal phosphino and pyridyl ligands, a set of new precursors were rationally designed and prepared. The reactions of trans-[(η5-C5Me5)2Mo2(μ-S)2S2] with 2 equiv. of [Cu(MeCN)]4(ClO4) and [Cu(MeCN)]4(PF6) resulted in [(η5-C5Me5)2- Mo2(μ3-S)4Cu2(MeCN)2](ClO4)2 (12) and [(η5-C5Me5)2Mo2(μ3-S)4Cu2(MeCN)2](PF6)2 (13). The direct reaction of 12 with pyradine (py), aniline and PPh3 gave corresponding cubane-like clusters [(η5-C5Me5)2Mo2(μ3-S)4Cu2(L)2](ClO4)2 (L = py (9), aniline (10), PPh3(11)). The reactions of [(η5-C5Me5)2Mo2(μ-S)2S2] and [Cu(MeCN)4]- (PF6) at room temperature produced a trans- gemel-like cluster [(η5-C5Me5)2Mo2(μ3-S)- (μ-S)2SCu(MeCN)](PF6) (14). A incomplete cubane-like cluster [(η5-C5Me5)2Mo2- (μ3-S)4CuCl] (15) was prduced by the reaction of [(η5-C5Me5)2Mo2(μ3-S)4(CuCl)2] with Na2S, which was used to remove one Cu(I) atom from the cubane. Because the coordinated MeCN molecules in 12, 13 and 14 are likely to be labile, some novel coordination polymers could be obtained when they are reacted with bridging ligands. Cluster 15 is likely to be completed by one more metal filling the void of its incomplete cubane, forming heterometallic clusters. Therefore, culsters 1215 were proved to be active precursors for the assembly of cluster-based coordination polymers.3. Clusters 12 and 13 were assembled through several bridging ligands including bipyridyls (1,4-pyrizine (pyz); 4,4'-bipyridyl (bpy); trans-1,2-bis(4-pyridyl)ethylene (bpee); 1,3-bis(4-pyridyl)propane (bpp); 1,2-bis(4-pyridyl)ethane (bpea)) and diphosphinos (1,2-bis(diphenylphosphine)methane (dppm); 1,2-bis(diphenylphosphine)- ethane (dppe) and 1,4-bis(diphenylphosphine)butane (dppb)). These ligands inter- connect the [Mo2S4Cu2] cores via the replacement of MeCN molecules. Three kinds of culsters, 1D polymeric clusters (zigzag type) {[(η5-C5Me5)2Mo2(μ3-S)4Cu2(L)](ClO4)2}n (L = pyz (16), bpy (17), bpee (18)), 1D polymeric cluster (linear type) {[(η5-C5Me5)2- Mo2(μ3-S)4Cu2(bpp)](ClO4)2}n (19) and cyclic dimeric clusters [(η5-C5Me5)2Mo2(μ3-S)4- Cu2(L)]2(X)4 (L = bpea, X = PF6 (20);L = dppe (21), dppb (22), dppmS (23), dppeS2 (24), X = ClO4-) were generated. In these reactions, the flexibility of the ligands was found to modulate the structures effectively. The third-order NLO properties of 12, 17, 18 and 2022 were studied. All these clusters showed excellent third-order NLO absorptions and self-defocusing effects. The hyperpolarizabilityγvalues correlate with the core-numbers while those of the diphosphino clusters are larger than those of the bipyridyl ones.4. Two main-group metal complexes of the zwitterionic ammonium thiolate complexes, [Pb(Tab)3](ClO4)2 (25) and [Bi(Tab)3](ClO4)3 (26) were prepared by electrochemical oxidation of Pb or Bi electrode in MeCN containing Tab and Et4NClO4. Each M atom in 25 and 26 is coordinated by three S atoms of three Tab ligands, forming a trigonal pyramidal coordination geometry. The resulting [M(Tab)3]n+ cations are interconnected by secondary M···S interactions to form two different 1D cationic chains. The electrochemical properties of 25 and 26 both consisted of one reversible reduction (to free metals) and two irreversible oxidations (the two-step oxidation of tab).
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