A square-planar hydrated cationic tetrakis(methimazole)gold(III) complex

The cationic pseudo-square-planar complex tetrakis(1-methyl-2,3-dihydro-1H-imidazole-2-thione-kappa S)gold(III) trichloride sesquihydrate, [Au(C4H6N2S)(4)]Cl-3 center dot 1.5H(2)O, was isolated as dark-red crystals from the reaction of chloroauric acid trihydrate (HAuCl4 center dot 3H(2)O) with four equivalents of methimazole in methanol. The Au-III atoms reside at the corners of the unit cell on an inversion center and are bound by the S atoms of four methimazole ligands in a planar arrangement, with S-Au-S bond angles of approximately 90 degrees.