Mercury complexes with 1,2,6,7-tetracyano-3,5-dihydro-3,5-diimino-pyrrolizinide

The anion 2-(5-amino-3,4-dicyano-2H-pyrrol-2-ylidene)-1,1,2-tricyanoethanide (L?, C11H2N7-), after isomerization to 1,2,6,7-tetracyano-3,5-dihydro-3,5-diimino-pyrrolizinide (L), forms different metal-complexes with mercury depending on the experimental conditions. Pure compounds were isolated from the reactions HL+CH3HgAc in CH3CN and NaL?+HgAc2 in AcH/H2O. They are CH3HgL and HgL2. From their optical spectra, compared to those of phthalocyaninato- or other well-known pyrrolizinato-complexes, the coordination geometry of Hg(II) in these species is supposed to be trigonal planar and trigonal monopyramidal, respectively. CH3HgL was characterized also by 1H NMR: (CD3CN, ?, ppm) 0.886 (CH3), 8.733 (NH). From the reactions in water between NaL? and HgCl2 or HgClO4 complex mixtures of polynuclear complexes were isolated of composition: 0.826 [Hg2ClL2(OH)]·0.174 [Hg4L3(OH)5]·2.06 H2O (A) or 0.588 [Hg2L2]·0.412 [Hg2L(OH)3]·3.53 H2O (B), respectively. The formulae A and B were based on thermogravimetric and elemental analysis data. Indirect evidences, based on XPS data, for the existence of the pyrrolizinato-Hg(I) complex are also given.