Gold(I) complexes of imidazole and thiazole-based diphos type ligands were prepared and their potential as chemotherapeutics investigated. Depending on the ligands employed and the reaction conditions complexes [L(AuCl)(2)] and [L(2)Au]X (X = Cl, PF(6)) are obtained. The ligands used are diphosphanes with azoyl substituents R(2)P(CH(2))(2)PR(2) {R = 1-methylimidazol-2-yl (1), 1-methylbenzimidazol-2-yl (4), thiazol-2-yl (5) and benzthiazol-2-yl (6)} as well as the novel ligands RPhP(CH(2))(2)PRPh {R = 1-methylimidazol-2-yl (3)} and R(2)P(CH(2))(3)PR(2) {R = 1-methylimidazol-2-yl (2)}. The cytotoxic activity of the complexes was assessed against three human cancer cell lines and a rat hepatoma cell line and correlated to the lipophilicity of the compounds. The tetrahedral gold complexes [(3)(2)Au]PF(6) and [(5)(2)Au]PF(6) with intermediate lipophilicity (logD(7.4) = 0.21 and 0.25) showed significant cytotoxic activity in different cell lines. Both compounds induce apoptosis and inhibit the enzymes thioredoxin reductase and glutathione reductase.

The gold(I) bis-NHC (NHC = imidazol-2-ylidene) parent compound was synthesised in high yield by a three step reaction starting from imidazole. The compound is highly water soluble and stable in concentrated hydrochloric acid.

A series of phosphanes with imidazolyl substituents were prepared as hemilabile PN ligands. The corresponding gold(I) complexes were tested as bifunctional catalysts in the Markovnikov hydration of 1-octyne, as well as in the synthesis of propargylamines by the three component coupling reaction of piperidine, benzaldehyde, and phenylacetylene. While the activity in the hydration of 1-octyne was low, the complexes are potent catalysts for the three component coupling reaction. In homogeneous solution the conversions to the respective propargylamine were considerably higher than under aqueous biphasic conditions. The connectivity of the imidazolyl substituents to the phosphorus atom, their substitution pattern, as well as the number of heteroaromatic substituents have pronounced effects on the catalytic activity of the corresponding gold(I) complexes. Furthermore, formation of polymetallic species with Au(2), Au(3), and Au(4) units has been observed and the solid-state structures of the compounds (5)(2)Au(3)Cl(2)]Cl and (3c)(2)Au(4)Cl(2)]Cl(2) (3c = tris(2-isopropylimidazol-4(5)-yl phosphane, 5 = 2-tert-butylimidazol-4(5)-yldiphenyl phosphane) were determined. The gold(I) complexes of imidazol-2-yl phosphane ligands proved to be a novel source for bis(NHC)gold(I) complexes (NHC = N-heterocyclic carbene). 1 Gold(I) catalysts with bifunctional P,N ligands Corinna Wetzel, [a] Peter C. Kunz,* [a] Indre Thiel, [a] Bernhard Spingler [b] [a] Institut für Anorganische Chemie und Strukturchemie I, Heinrich-Heine Universität Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany. Fax: (+)49 211 8112287; E-mail:peter.kunz@uni-duesseldorf.de.

Seven novel imidazole and thiazole derivatives of diphos-type ligands are presented. They are of the general structure R2P(CH2)(2)PR2, where R is imidazol-2-yl (1), 1-methylimidazol-2-yl (2), 1-methyl-benzimidazol-2-yl (3), 1-methylimidazol-5-yl (4), 2-isopropylimidazol-4(5)-yl (5), thiazol-2-yl (6), benzothiazol-2-yl (7), thiazol-4-yl (8) or thiazol-5-yl (9). Syntheses involved direct metallation or halogenmetal exchange reactions. Their solubility, especially in aqueous solution, is strongly dependent on the nature of the substituents as is their partition coefficient log D. The crystal structures of compounds 2, 3, 7a and 9 as well as the structure of the rhodium complex (2)(2) , Corinna Wetzel [a] , Melanie Bongartz [a] , Anna-Louisa Noffke [a] and Bernhard Spingler

The addition of hexa­fluorido­phosphate salts (ammonium, silver, thallium or potassium) is usually used to precipitate complex cations from aqueous solutions. It has long been known that PF6 − is sensitive towards hydrolysis under acidic conditions [Gebala & Jones (1969 ▶). J. Inorg. Nucl. Chem. 31, 771–776; Plakhotnyk et al. (2005 ▶). J. Fluorine Chem. 126, 27–31]. During the course of our investigation into coinage metal complexes of diphosphine ligands, we used ammonium hexa­fluorido­phosphate in order to crystallize [Ag(diphos­phine)2]PF6 complexes. From these solutions we always obtained needle-like crystals which turned out to be the title compound, 2NH4 +·HPO4 2−. It was received as the hydrolysis product of NH4PF6. The crystals are a new modification of diammonium hydrogen phosphate. In contrast to the previously published polymorph [Khan et al. (1972 ▶). Acta Cryst. B28, 2065–2069], Z′ of the title compound is 2. In the new modification of the title compound, there are eight mol­ecules of (NH4)2(HPO4) in the unit cell. The structure consists of PO3OH and NH4 tetra­hedra, held together by O—H⋯O and N—H⋯O hydrogen bonds.