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

Abstract

Trichlorido(4-methylpiperidine)gold(III), [AuCl3(C6H13N)], 1, crystallizes in Pbca with Z = 8. Tribromido(4-methylpiperidine)gold(III), [AuBr3(C6H13N)], 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 AuX3 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 AuX3 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.

Keywords

• crystal structure
• gold
• methylpiperidine
• hydrogen bonds
• polymorph