Crystal structures of trichlorido(4-methylpiperidine)gold(III) and two polymorphs of tribromido(4-methylpiperidine)gold(III)

Trichlorido(4-methylpiperidine)gold(III), [AuCl 3 (C 6 H 13 N)], 1 , crystallizes in Pbca with Z = 8. Tribromido(4-methylpiperidine)gold(III), [AuBr 3 (C 6 H 13 N)], 2 , crystallizes as two polymorphs, 2a in Pnma with Z = 4 (imposed mirror symmetry) and 2b , which is isotypic to 1 . The Au—N bonds trans to Cl are somewhat shorter than those trans to Br, and the Au—Cl bonds trans to N are longer than those cis to N, whereas the Au—Br bonds trans to N are slightly shorter than the cis bonds. The methyl and Au X 3 groups ( X = halogen) occupy equatorial positions at the six-membered ring. The packing of all three structures involves chains of molecules with offset stacking of the Au X 3 moieties associated with short Au... X contacts; for 1 and 2b these are reinforced by N—H... X hydrogen bonds, whereas for 2a there are no classical hydrogen bonds and the chains are interconnected by Br...Br contacts.