GOLD(III) DERIVATIVES WITH C(4)-AURATED 1-PHENYLPYRAZOLE

The reaction of 1-phenylpyrazole (HL), with gold(III) chloride has bee n studied. Besides a 1:1 adduct [Au(HL)Cl-3] 1, where the ligand is bo nded through the nitrogen atom, several C(4) aurated species have been isolated. Thus treatment of [AuCl3](2) with HL in dichloromethane sol ution affords a complex, [Au(L)Cl2HCI](n), 2, where the gold atom is b onded to the 4-carbon atom of the pyrazole ligand. Deprotonation of co mplex 2 by means of the not coordinating base 1,8-bis(dimethylamino)na phthalene (proton sponge), B, affords the salt [BH][Au(L)Cl-3], 3, whe reas reaction of 2 with 3,5-Me(2)py and PPh3 (molar ratio 1:2) gives t he neutral species trans-[Au(L)(3,5-Me(2)py)Cl-2, 4, and cis-[Au(L)(PP h3)Cl-2] 5, respectively. The structure of compound 4 solved by X-ray diffraction, unambiguously shows the anionic ligand L bonded to the go ld ion through the C4 atom. Alternatively, compounds 4 and 5 can be ob tained in two steps, i.e. deprotonation of 2 with NaOH to give [Au(L)C l-2](n) 6, and reaction of 6 with 3,5-Me(2)py and PPh3, respectively. The new species were characterized by elemental analyses, conductivity measurements, IR, NMR and FAB-MS spectroscopy. (C) 1998 Elsevier Scie nce S.A. All rights reserved.