Crystal Structures of the Zn II Complexes

3 Crystal Structures ofZn(II) Complexes with Substrate Mimics 

To further investigate the nature of substrate binding the complex [Zn2(CH3L2)(CH3COO)2](PF6) was crystallized from acetonitrile/water 1 1 with 25 equivalents of BPNPP. Colorless crystals suitable for X-ray crystallography 

The Zn-O-Zn angles [Zo4(BrL2)2(P03F)2(H20)2](PF6)2 and [Zn4(CH3L2)2 (N02C6H50P03)2(H20)2](PF6)2 Were found to be at least 10° larger than in the respective complexes with bridging acetate. Mass spectral analysis, IR and microanalysis indicated that the structure was representative of the whole sample obtained in the synthesis with wet sodium hexafluorophosphate. 

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Crystal Structures of the Zn(II) Complexes with CH3HL4 and CH3HL5... 

Fig. 35 Left Molecular structure of dipicatriz. Right side views of the crystal structures of the Zn(II) and the Cu(II) trinuclear complexes of dipicatriz. The structures show the three coordinate Zn(II) and Cu(ll) ions in scaled ball-and-stick representation and the distances between the centroids of the triazine ring and the closest oxygen atoms of the interacting nitrate anions...

Kumar, P.K., P. Bhyrappa, and B. Varghese (2003). An improved protocol for the synthesis of antipodal 6-tetrabromo-tetraphenylporph5nin and the crystal structure of its Zn(II) complex. Tetrahedron Lett. 44, 4849-4851. 

Pedrido etal. [148] also described the electrochemical synthesis and characterization of new neutral Zn(II), Cd(II), and Pb(II) complexes withbis(4-Ai-methylthiosemicarbazone)-2,6-diacetylpy-ridine. The properties and crystal structure of the obtained complexes were studied. 

The X-ray crystal structure of the inorganic phosphate (an inhibitor) complex of alkaline phosphatase from E. coli (9) showed that the active center consists of a Zn2Mg(or Zn) assembly, where the two zinc(II) atoms are 3.94 A apart and bridged by the bidentate phosphate (which suggests a phosphomonoester substrate potentially interacting with two zinc(II), as depicted in Fig. 2), and the Mg (or the third Zn) is linked to one atom of the zinc pair by an aspartate residue at a distance... 

Crystal structures of the benzotriazole complexes [Zn(HL)Cl2] and [Zn2L4] (HL = benzotriazole 62) have been reported the former compound has the metal in a tetrahedral N2C12 environment (Zn—N, 2.014, 2.034 A Zn—Cl, 2.241, 2.235 A) and the latter is a polymeric species.441 The complex [H2L]2[ZnCU] (HL = 62) has also been described it is isostructural with the tetrachlorocobaltate(II) analogue, which has previously been structurally characterized.441 The synthesis and powder diffraction pattern for [ZnL Cy (L = 62) have also been reported.442 Complexes of the type MX2L2 (M - Zn, X = Cl, Br, I or SCN M = Cd, X = Cl L = allyl or 3,5-dimethylpyrazole) have been synthesized where L is 3,5-dimethylpyrazole, cadmium also forms the complexes (CdBr2L3 and CdI2L4. When L is allylpyrazole, alkene coordination is not observed thiocyanate is N-bonded.443,444... 

Crystal structures of the related complexes tetraaquabi (2,4-dichlorophenoxyacetato)zmc(II) and diaquabi (2,4-dichlorophenoxyacetato)zinc(II) have been reported, in which two distinct metal environments occur. In the [Zn(H20)4L2] (HL = 2,4-dichlorophenoxyacetic acid) molecule (109) the metal is in an octahedral 06 environment, with a trans diaxial arrangement of... 

The novel species obtained from the reaction of zinc(II) salts with thiophenol have been further investigated and complexes of formula [Zn4(SPh)8(ROH)] have been isolated from the interaction of Zn[C03] and PhSH in ROH. A crystallographic study of these species has shown that they should be formulated cflte -( -SPh) ( -SPh) n4(ROH)(SPh) and that they form one-dimensional polymeric crystals with one intercluster bridging PhS unit. A crystal structure of the complex [Me4N] [ClZn4( -SPh)i2(ZnSPh)4], formed from Zn(N03)2, PhSH, Pr3N and [Me4N]Cl, has also been reported.823... 

The Zn(II) ion is held by the tetra8iza assembly and further coordinated by the labile pendant alcohol, which simulates Ser 102 in the enzyme. Under these conditions, the pendant alcohol is activated toward deprotonation such that its pl drops from about 15 to 7.51 (at 298 K). Above pH 7.5, deprotonation of the pendant alcohol rather than a coordinated water molecule, was shown by NMR spectral changes associated with the protons in the pendemt arm and by the crystal structure of the deprotonated Zn(II) complex (Fig. 1). Apparently, [Zn(3)]+ hydrolyzes phosphomonoesters too slowly for ease of investigation however, the reaction with a phosphodiester, bis(4-nitrophenyl) phosphate, which is sufficient to cleuify the proposed cooperative role of Ser 102 and Zn(II) in alkahne phosphatases, is considerably faster and was... 

The titration with cobalt(II) shows a sharp endpoint close to the Co ligand ratio of 0.67 expected for the formation of a triple helical [Co2(6-bismbmp)3] complex, and the crystal structure of the isolated product confirms this [15]. The titration with Cu(I) shows a much less well defined endpoint, which is however around a metal ligand ratio of 1, as expected for a double helical complex [Cu2(6-bismbmp)2], while the titration with Zn(II) shows a very complicated evolution which clearly shows the formation of more than one complex. 

The Zn(II) complexes were typically synthesized by adding two equivalents of zinc(ll) acetate dUiydrate dissolved in a small amount of methanol to a ligand solution in methanol and refluxing the mixture for 30 min to ensure complete binding of two equivalents of Zn(ll) to the ligands. Sodium hexafluorophosphate was employed as counter ion as it proved to be the most successful anion for obtaining crystals suitable for X-ray structure determination (Fig. 4.5). 

As a template for the formation of a trefoil knot, Hunter et al. employed the self-assembly of three bipyridine units of a single linear strand around an octahedral zinc(II) metal center. The templation of the knotted structure was evidenced by an x-ray crystal structure of the intermediate Zn complex (Scheme 17.2, CCDC163073). ... 

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