Investigation of Protonation of the Tetraazamacrocyclic Complex of Gold(III) [Au(C14H22N4)]+ in Water. Synthesis and Crystal and Molecular Structures of [Au(C14H23N4)](ClO4)2

The equilibrium of protonation of tetraazamacrocyclic complex of gold(III) [AuL]+ (L = 5,7,12,14-tetramethyl-1,4,8,11-tetraazacyclotetradeca-4,6,11,13-tetraenato(2-)) in a water solution has been investigated. A monoprotonated tetraazamacrocyclic metallocomplex with two inequivalent (iminate and imine) six-membered chelate cycles and charge 1- was obtained and isolated for the first time. The compound [AuHL](ClO4)2 was characterized by chemical analysis, IR and UV-VIS spectroscopy, powder and single crystal X-ray diffraction. The proton was shown to be attached to the β-carbon of one of the two six-membered chelate rings of the macrocycle. Crystal data for [AuHL](ClO4)2 are: a = 7.693(1) Å, b = 17.366(2) Å, c =15.172(2) Å; β = 96.82(1)°, V = 2012.6(4) Å3, Z = 4, dcalc = 2.123 g/cm3, space group P21/c. The structure is built from practically planar [Au(C14H23N4)]2+ cations and perchlorate anions [ClO4]−.