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

Spectral and electro-chemical characterization of transition metal complexes of a modified [N6] macrocycle. A mimic to cyclic hexapeptide

“…The electro-chemical behaviour of the present complex appears to be entirely different from that reported [29] for tetra aza [N 4 ]-Pt(II) complex. The latter does not show formation of either reversible or quasi-reversible redox wave in solution, rather indicates presence of an irreversible anodic and cathodic waves.…”

Cyclic polyamines via a molybdenum(0) templated Mannich-type reaction

“…This undecane triazamacrocycle with an additional pendant amine donor should act as a tetradentate ligand, with the donor predispositions enforcing cis-MN 4 X 2 stereochemistry with octahedral metal ions. This amine-pendant triazamacrocycle represents a new member of a class of pendant-arm macrocycles prepared through similar Mannich-type chemistry, previously represented by the widely studied tetraazamacrocycles [4][5][6][7][8] and one example of a pentaazamacrocycle [24]. Coordination of the new macrocycle to cobalt(III) was achieved, with the ligand bound as a tetradentate from spectroscopic behaviour of the complex.…”

“…Subsequently, a range of more inert metal ions including Pd(II), Pt(II) and Au(III) have been shown to be effective [6][7][8]. Earlier, macrobicyclisation has been described around inert octahedral ions such as Co(III) [9], Rh(III) [10], Ir(III) [11], and Pt(IV) [12].…”