New Bis(mercaptoimidazolyl)(pyrazolyl)borate Ligands and Their Zinc Complex Chemistry

Shu, Mouhai; Walz, Rainer; Wu, Biao; Seebacher, Jan; Vahrenkamp, Heinrich

doi:10.1002/ejic.200300079

Cited by 57 publications

(55 citation statements)

References 27 publications

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“…This attachment of an external hydrogen-bond acceptor seems to be a common feature of all zinc-alcohol complexes with tripodal ligands. [3][4][5] Likewise, the Zn-O bond lengths in both complex units of 21 (av. 1.98 Å) lie within the small range of such bond lengths observed before (1.97-2.01 Å), [3][4][5] and they are nearly identical to the one in the pentafluorobenzyl alcohol adduct of alcohol dehydrogenase (ADH).…”

Section: Complexes With Alcohol and Aldehyde Ligandsmentioning

confidence: 99%

“…While the preparation of tris(pyrazolyl)borates requires high-temperature reactions between KBH 4 and the pyrazoles in a melt, the thioimidazoles react with KBH 4 under milder conditions, typically in boiling toluene. This made the synthesis of ligands L1-L6 an easy, high-yield process, the most time-consuming part of which is actually the twostep synthesis of the substituted thioimidazoles, whose overall yields rarely exceed 50 %.…”

Section: Ligand Synthesismentioning

confidence: 99%

“…We [3,4] and others [5][6][7][8][9] have tried to model the structure and function of these enzymes by applying tripodal scorpionate [10] ligands bearing one to three sulfur donors. During these studies Parkin's [5,8,11,12] and our own research group [3,13] have found that the sulfur-rich environment of the tris(thioimidazolyl)borate ligands (Tti R ) enables the attachment of quite unusual and biologically relevant coligands X at the zinc ion in an S 3 ZnX environment.…”

Section: Introductionmentioning

confidence: 99%

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New Tris(thioimidazolyl)borate Ligands and Some Zinc Complexes Thereof

2005

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In order to improve the encapsulation of metal ions coordinated by tris(thioimidazolyl)borate ligands, four new such ligands with o-substituted phenyl substituents were synthesised as well as ones with p-tolyl and cyclohexyl substituents. In order to provide a basis for their bioinorganic zinc complex chemistry, they were converted to some zinc-halide, -carboxylate, -nitrate, -phenolate and -benzylate complexes. They

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Section: Complexes With Alcohol and Aldehyde Ligandsmentioning

confidence: 99%

Section: Ligand Synthesismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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New Tris(thioimidazolyl)borate Ligands and Some Zinc Complexes Thereof

2005

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“…Treatment of the monotopic tripod [5] À with CuCl and CuBr 2 results in the formation of complexes K[Cu (5) ((N 2 P), [13,14] (NP 2 ) [15] ) or nitrogen and sulfur donors ((N 2 S), [16] (NS 2 ) [17][18][19][20][21][22] ). These derivatives are most interesting, because they allow a smooth modulation of the coordination environment between the extremes (N 3 ) and (P 3 )/(S 3 ).…”

Section: Introductionmentioning

confidence: 99%

Copper Complexes of Mono‐ and Ditopic [(Methylthio)methyl]borates: Missing Links and Linked Systems En Route to Copper Enzyme Models

Ruth

Tüllmann

Vitze

et al. 2008

Chemistry A European J

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TMEDA-free (TMEDA: tetramethylethylenediamine) LiCH(2)SMe is a suitable reagent for the selective introduction of (methylthio)methyl groups into PhBBr(2) and its p-silylated derivative Me(3)Si--C(6)H(4)--BBr(2). The resulting compounds, R*--C(6)H(4)--B(Br)(CH(2)SMe) (R*=H: 2; R*=SiMe(3): 7) and PhB(CH(2)SMe)(2) (3), form cyclic dimers through B--S adduct bonds in solution and in the solid state. Compounds 2 and 3 have successfully been used for preparing the (N(2)S) scorpionate [PhBpz(2)(CH(2)SMe)](-) ([5](-)) (pz: pyrazol-1-yl) and the (NS(2)) scorpionate [PhBpz(CH(2)SMe)(2)](-), respectively. Compound 7 proved to be an excellent building block for the heteroditopic poly(pyrazol-1-yl)borate p-[pz(3)B--C(6)H(4)--Bpz(2)(CH(2)SMe)](2-) ([10](2-)) that mimics the two ligation sites of the copper enzymes peptidylglycine alpha-hydroxylating monooxygenase and dopamine beta-monooxygenase. Treatment of the monotopic tripod [5](-) with CuCl and CuBr(2) results in the formation of complexes K[Cu(5)(2)] and [Cu(5)(2)]. An X-ray crystallography study of K[Cu(5)(2)] revealed a tetrahedral (N(2)S(2)) coordination environment for the Cu(I) ion, whereas the Cu(II) ion of [Cu(5)(2)] possesses a square-pyramidal (N(4)S) ligand sphere (S-atom in the axial position). The remarkable redox properties of K[Cu(5)(2)] and [Cu(5)(2)] have been assessed by cyclic voltammetry and quantum chemical calculations. The reaction of K[Cu(5)(2)] with dry air leads to the Cu(II) species [Cu(5)(2)] and to a tetranuclear Cu(II) complex featuring [PhB(O)pz(2)](2-) ligands. Addition of CuCl to K(2)[10] gives the complex K(3)[Cu(10)(2)] containing two ligand molecules per Cu(I) center. The Cu(I) ion binds to both heteroscorpionate moieties and thereby establishes a coordination environment similar to that of the Cu(I) ion in K[Cu(5)(2)].

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“…. EtOH Shu et al, 2003; (tim o-An = 1-(o-anisyl)-2-thioimidazole) which provides the best structural model to date for LADH. Interestingly, the sulfur rich coordination environment provided by poly(thioimidazolyl)borate ligand stabilizes coordination of the alcohol to zinc, thereby suggesting that one of the reasons why LADH utilizes a sulfur rich coordination environment is to promote coordination of the alcohol relative to that of water.…”

Section: Zinc Biomimetic Systemsmentioning

confidence: 99%