Bimetallic cyanide-bridged complexes based on the photochromic nitroprusside anion and paramagnetic metal complexes

Three novel compounds formed by the photochromic nitroprusside anion, [Fe(C N)(5)NO](2-), and the paramagnetic complexes [Cu(C19H18N6)](2+), [Ni(C6H14N 2)(2)](2+) and [Ni(cyclam)](2+) are reported. The structure of [Cu(C19H18N6 )][Fe(CN)(5)NO] (1) comprises binuclear complexes with a [Fe(CN)(5)NO](2-) anion linked to a [Cu(C19H18N6)](2+) cation. The structure of [Ni(C6H14N2)( 2)][Fe(CN)(5)NO].6.5H(2)O (2) and [Ni(cyclam)][Fe(CN)(5)NO]. 4H(2)O (3) con sists of zigzag chains formed by an alternate array of the paramagnetic cat ions and [Fe(CN)(5)NO](2-) anions. The three compounds are paramagnets; a f ourth compound containing [cis-Ni(en)(2)](2+) cations and [Fe(CN)(5)NO](-) anions does not show a change in the magnetic properties after irradiation. In compounds 1 and 2 the first metastable state of the nitroprusside anion has been detected by differential scanning calorimetry at 172 and 180 K, r espectively. (C) 2001 Elsevier Science Ltd. All rights reserved.