The 1-substituted tris(2-thioimidazolyl)hydroborate ligands Tt(R) were prepared as the potassium salts from KBH(4) and the corresponding 1-R-2-thioimidazole for R = t-Bu and C(6)H(4)-p-CH(CH(3))(2) (Cum). Their reactions with zinc salts yielded the tetrahedral complexes Tt(R)Zn-X with X = F, Cl, ONO(2) and (Tt(t)()(-)(Bu))(2)Zn. With zinc perchlorate the labile perchlorate complexes Tt(R)Zn-OClO(3) were obtained. They served as starting materials for the incorporation of substrates which are relevant for the chemistry of horse liver alcohol dehydrogenase: Ethanol led to [Tt(t)()(-Bu)Zn.EtOH] ClO(4).EtOH, p-nitrophenol (NitOH) yielded Tt(Cum)Zn-ONit. Pyridine-2-carbaldehyde and salicylic aldehyde were incorporated as N(pyridine) and O(phenolate) coligands with possible additional O(aldehyde) coordination. Substituted pyridyl methanols (R-PyCH(2)OH) yielded the trinuclear complexes [(Tt(t)()(-Bu))(2)Zn(3)(R-PyCH(2)O)(2)] (ClO(4))(2) with bridging Tt and pyridylmethoxide ligands. Preliminary experiments on the functional modeling of alcohol dehydrogenase have shown that TtZn complexes promote both the dehydrogenation of 2-propanol and the hydrogenation of pentafluorobenzaldehyde.

Bis(pentafluorothiophenolato)zinc (1) and bis(2,4,6-triisopropylthiophenolato)zinc (2) can be combined with nitrogen-containing derivatives of benzyl alcohol and benzaldehyde to form (N,O-chelate) zinc thiolates. 2-Pyridylmethanol as well as 2-quinolylmethanol (HetMeOH) yield [(HetMeO)Zn(SR)](4) (3, 4) having a cyclo-Zn(4)(&mgr;-O)(4) backbone and only terminal SR. Likewise, thiolate 1 and 2-(dimethylamino)benzyl alcohol form zwitterionic [(dimethylammoniobenzylato)Zn(SR)(2)](2) (5) with bridging alkoxide and terminal thiolate. In contrast, 6-picolylmethanol (PicMeOH) and thiolate 1 result in [(PicMeOH)Zn(SC(6)F(5))(2)] (6) containing zinc in a tetrahedral ZnNS(2)O, environment. Simple aromatic aldehydes form polymeric complexes [(RCHO)Zn(SC(6)F(5))(2)] (7: R = p-tolyl, 8: R = mesityl) with a [Zn-S](infinity) backbone. Chelating aldehydes (CA) yield mononuclear complexes with tetrahedral ZnNS(2)O coordination [(CA)Zn(SC(6)F(5))(2)] (9, CA = pyridine-2-carbaldehyde; 10, CA = 6-methylpyridine-2-carbaldehyde; 11, CA = 6-methoxypyridine-2-carbaldehyde; 12, CA = quinoline-2-carbaldehyde; 13, CA = 2-(dimethylamino)benzaldehyde). In contrast, N-methylimidazole-2-carbaldehyde (ImA) is coordinated twice in tetrahedral [(ImA)(2)Zn(SC(6)F(5))(2)] (14) lacking any Zn-O interactions. Pyridine-2,6-dicarbaldehyde (PDA) forms trigonal bipyramidal [(PDA)Zn(SC(6)F(5))(2)] (15) with ZnNO(2)S(2) ligation. The structures of 3, 4, 6, 8, 10, 11, 13, and 14 were determined crystallographically, and the structures of 5 and 15 were deduced from those of the corresponding ZnBr(2) complexes. The ZnNS(2)O coordination pattern observed for the enzyme has been reproduced to a very good approximation. In complexes 6 and 10, which are almost superimposable, it is realized for both the corresponding alcohol and aldehyde.

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The synthesis of two new dithiols, 1,8‐dimercapto‐2,7‐di(tert‐butyl)naphthalene (H2L1) and 1,8‐dimercaptonaphthoic anhydride (H2L2), is described. They react with diethylzinc to yield the polymeric complexes L1Zn and L2Zn. L1Zn dissolves in the presence of pyridine to form [L1Zn·py]x, which is presumed to be dimeric. Both L1Zn and L2Zn react with neocuproin. Structure determinations have confirmed the tetrahedral ZnN2S2 coordination in the resulting LZn·neo complexes.

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