Platinum(II) Template Synthesis of a Pendant-Arm Macrocycle

Abstract

Platinum(II)-directed condensation of ethane-1,2-diamine with nitroethane and formaldehyde yields the colourless macrocyclic complex (trans-6,13-dimethyl-6,13-dinitro-1,4,8,11-tetraazacyclotetradecane)plat- inum(II), [Pt(1)]²⁺, in good yield. This parallels chemistry reported earlier around other triad members nickel(II) and palladium(II). The pendant nitro groups in the major isomer are disposed on opposite sides of the macrocycle in a trans geometry, as confirmed by the X-ray crystal structure analysis of [Pt(1)] (ClO₄)₂, which crystallizes in the triclinic space group P^-1, a 8·041(4), b 8·482(4), c 9·443(3) Å, α 69·44(3), β 67·66(4), γ 71·73(4)°,Z1, and was refined to an R value of 0·027 on 1920 F. The platinum ion lies in a square planar environment of four nitrogen donors, with typical Pt–N distances; comparisons between the platinum(II) and palladium(II) complexes of (1) and its analogue (2), with diammonio groups in place of dinitro groups, are discussed