Zinc complexes with

Single-phase ZnS films of a fine grain size (no XRD shown) and a band gap of 3.7 eV were electrodeposited from aqueous alkaline (pH 8-10) solutions of zinc complexed with EDTA, and thiosulfate as a sulfur source [101]. The voltammet-ric data implied that deposition occurred either by S-induced UPD of Zn or by a pathway involving both Zn " and thiosulfate concurrently. 

The value of the tris(pyrazolyl)hydroborato complexes [TpRR ]ZnOH is that they are rare examples of monomeric four-coordinate zinc complexes with a terminal hydroxide funtionality. Indeed, [TpBut]ZnOH is the first structurally characterized monomeric terminal hydroxide complex of zinc (149). As such, the monomeric zinc hydroxide complexes [TpRR ]ZnOH may be expected to play valuable roles as both structural and functional models for the active site of carbonic anhydrase. Although a limitation of the [TpRR ]ZnOH system resides with their poor solubility in water, studies on these complexes in organic solvents... 

The zinc complexes with diphenyl-2-pyridylmethane, ZnL2Cl2 and ZnL2Br2, have been characterized by IR spectroscopy and conductivity measurements.107 The [(pyridyl)2P(NSi Mc3)2] ligand forms an aminoiminophosphoranate complex with zinc which structural characterization shows to be four-coordinate bound to two pyridyl and two amide nitrogen donors (3).108... 

Diethylenetriamineacetic acid has been used in the formation of homodinuclear zinc complexes with the bridging imidazole. The crystal structure of [LZn(imidazolate)ZnL]C104 was obtained. The magnetics of the heterodinuclear Cu-Zn complex were studied and single crystal EPR of the Zn2 dimer doped with the CuZn dimer.139... 

A structurally characterized example of a dinuclear zinc complex with a bridging phosphate monoester was provided by Kitajima and co-workers using the tris(pyrazolyl)borate ligand system. The P—O bond in a tris- or bis-phosphate ester is cleaved by a hydroxo zinc complex resulting in the monoester compound.443... 

Triply bridging carbonates between three zinc centers have been identified in nine different X-ray structures deposited in the CSD 458,461,465-467 For example, a binuclear ft-OH zinc complex with a tetradentate /V-donor ligand absorbs atmospheric carbon dioxide to a triply bridged carbonate.468 Examples are also known where the metal atoms are in varying coordination environments. The complex cation [Zn3(bipyridine)6(/U3-C03)(H20)2]4+ contains one penta- and two hexacoordinate zinc centers.469 A tetrapodal compartmental ligand forms a tetrameric complex with zinc that contains the carbonate bridging between three of the four zinc centers.470... 

Varying ratios of the ligands 7V-(2-thiophenyl)-2,5-dimethylpyrrole and V-methylimidazole were used to form tetrahedral zinc complexes with S4, S3N, and S2N2 coordination spheres. X-ray structural analyses and IR spectra were recorded for all compounds and the relevance to zinc finger proteins was discussed. The comparison to cobalt and cadmium structures showed only minor differences, supporting the theory that changes on substituting these metals into zinc proteins would be minor.538... 

Pendent arm 1,4,7-triazacyclononane macrocycles (91) and (92) have been used to stabilize the zinc-to-phenoxyl bond allowing characterization of these compounds.477 The interest in the zinc complexes comes from the wide potential range in which it is redox stable allowing observation of the ligand-based redox processes, this allows study of the radical by EPR and the electronic spectra is unperturbed by d-d transitions. Macrocycles of the type l,4,7-tris(2-hydroxybenzyl)-1,4,7-triazacylononane form a bound phenoxyl radical in a reversible one-electron oxidation of the ligand. The EPR, resonance Raman, electronic spectra, and crystal structure of the phenoxide complexes were reported. This compound can be compared to a zinc complex with a non-coordinated phenoxyl radical as a pendent from the ligand.735... 

Figure 14 Molecular structure showing the helical nature of the zinc complex with a 19-methoxyoctaethyl-bilinone ligand formed on ring opening of the oxaporphyrin macrocycle.828...

A hexadentate N202S2 ligand (116) has been synthesized as a dithiaalkyl-substituted triazene-1-oxide and forms an unusual hexacoordinated zinc complex with thioether donors. Both the phenyl and the methyl derivatives form structurally characterized octahedral complexes.896... 

The demonstration of the formation of a hexanuclear zinc complex with the S-donor ligand 2-aminoethanethiolate, containing Zn3S3 and Zn4S4 cyclic units, contributes to the building up of a pattern of polynuclear complex formation based on coordination preferences of the metal ions involved (320) - reaction of Zn2+ with salicylideneamino ligands and pyrazine can give linear tetranuclear complexes (321). Another hexanuclear zinc complex appears in the section on supramolecular chemistry below (Section VII.D). 

On treating diisobutene with acetic anhydride and anhydrous zinc chloride, A. C. Byrns and T. F. Doumani had isolated in 1943 a crystalline compound to which they had ascribed the structure of a zinc complex with a 1,3-diketone 40 the correct pyrylium chlorozincate structure was established by A. T. Balaban et al.41 in 1961, after extended investigation on the formation of pyrylium salts by alkene diacylation.42 This formation again had remained undetected for many decades during which alkenes had been acylated but only the water-insoluble monoacylation products had been investigated, whereas the water-soluble pyrylium salts went into the sink with the Lewis or Bronsted acid catalysts that had been used in the acylation. 

The goal of the experiments we report was to create new structural model complexes for gluzincins or carboxypeptidases. With [Zn (bdtbpza)Cl] (12) for the first time a tetrahedral zinc complex with a monoanionic W,W,0-tridentate using a carboxylate 0-donor was synthesized (41). A comparison of the molecular structure of 12 with the coordination environment of the enzymes indicates its significance... 

Scheme 13. Synthesis of alkyl zinc complexes with his(pyrazol-l-yl) acetato ligands (47).

The complexes ML2-nH20 (M = Zn or Cd H2L = diformyl- or diacetyl-hydrazine) have also been synthesized, and are dimeric or polymeric with the quadridentate hydrazine acting as a bridging ligand.158 159 A normal coordinate analysis of diformylhydrazine and its zinc complex with deprotonated ligand has been reported.160... 

Rather earlier but still recent studies include those of zinc complexes with glycine,270,273 alanine,272,274 /5-alanine,272 norleudne,271 phenylalanine,272 proline, methionine, serine,274 histidine,271 asparagine,276 adrenaline,277 noradrenaline,277 terizidone,278 S-ethyl-L-cysteine,279 5,5 -methylenebis(L-cysteine),280 ornithine, lysine, 2,4-diaminobutyric add and 2,3-diaminopropionic acid.281... 

The terdentate ligand ft-(2-pyridyl)alanine forms zinc complexes with a considerable degree of enantioselectivity.524 Zinc complexes of 2-pyridyl azo compounds,525 oximes526 and sulfonamides527 have also been described. 

The formation of zinc complexes with a further series of [14Jane-N4 macrocycles has been investigated.1127 The macrocycle [9]ane-l-0-4,7-N2 forms a zinc complex,1128 and the crown ether complex [ZnL][SbQ6]2 (L = 18-crown-6) has also been characterized.1129 Zinc complexes of a range of encrypting ligands have been studied.1130,1131... 

Fig. 6.51 Dendritically linked porphyrin/zinc complexes with fullerene at the focal point (according to Aida et al.)...

ZINC, Complex with 1,IO-PHENANTHROLINYLENE ZINC CHLORIDE ZINC SULFATE (1 1)... 

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