Ni(II) complexes of dithiophosphonic acids

The reaction of 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide (Lawesson reagent) with isobutanol, cyclohexylamine and phenylethylamine produced (4-methoxy-phenyl)-phosphonodithioic acid o-isobutyl ester HS2P(p-C6H4OMe) (OCH2CH(CH3)(2)) (I) [S2P(C6H11NH)(p-C6H4OMe) H3N+C6H11] (II) and [S2P(phCH(2)CH(2)NH) (p-C6H4OMe)H(3)N(+)CH(2)CH(2)ph] (III), respectively. The reaction of alcohol with Lawesson reagent produced neutral product (I) while that with amines led to an ion pair (H, III). Furthermore, reaction of I, II and III with NiCl2.6H(2)O in methanol produced novel complexes: IV, V and VI. The compounds were characterized by H-1, C-13 and P-31 NMR, IR spectroscopy and elemental analysis. The single crystal X-ray structures of IV and V showed that the nickel complexes are square planar. Compound V formed a three-dimensional supramolecular structure via intermolecular P-O...H-N hydrogen bonds. The Xray crystallography of V showed that those three hydrogens of +NH3 cation produced three hydrogen bonds with different distances. The new compounds were additionally tested in view of their anti-bacterial properties. The ligands containing amine substituents exhibited more activity toward tested bacteria than their alcohol substituents, while the Ni(II) complexes including alcohol substituents exhibited high potential.