Bimetallic cyanide-bridged complexes based on the photochromic nitroprusside anion and paramagnetic metal complexes. Syntheses, structures, and physical characterization of the coordination compounds [Ni(en)(2)](4)[Fe(CN)(5)NO](2)[Fe(CN)(6)]center dot 5H(2)O, [Ni(en)(2)][Fe(CN)(5)NO]center dot 3H(2)O, [Mn(3-MeOsalen)(H2O)](2)[Fe(CN)(5)NO], and [Mn(5-Brsalen)](2)[Fe(CN)(5)NO]

The synthesis, crystal structure, and physical characterization of the coor dination compounds [Ni(en)(2)](4)[Fe-(CN)(5)NO](2)[Fe(CN)6]. 5H(2)O (1), [N i(en)(2)][Fe(CN)(5)NO]. 3H(2)O (2), [Mn(3-MeOsalen)(H2O)](2)[Fe(CN)(5)NO] ( 3), and [Mn(5-Brsalen)](2)[Fe(CN)(5)NO] (4) are presented. 1 crystallizes i n the monoclinic space group P2(1)/n (a = 7.407- (4) Angstrom, b = 28.963(6 ) Angstrom, c = 14.744(5) Angstrom, alpha = 90 degrees, beta = 103.26(4)deg rees, gamma = 90 degrees. Z = 2). Its structure consists of branched linear chains formed by cis-[Ni(en)(2)](2+) cations and ferrocyanide and nitropru sside anions. The presence of two kinds of iron(II) sites has been demonstr ated by Mossbauer spectroscopy. 2 crystallizes in the monoclinic space grou p P2(1)/c (a = 11.076(3) Angstrom, b = 10.983(2) Angstrom, c = 17.018(5) An gstrom, alpha = 90 degrees, beta = 107.25(2)degrees, gamma = 90 degrees, Z = 4). Its structure consists of zigzag chains formed by an alternated array of cis-[Ni(en)(2)](2+) cations and nitroprusside anions. 3 crystallizes in the triclinic space group P (1) over bar (a = 8.896(5) Angstrom, b = 10.43 0(5) Angstrom, c = 12.699(5) Angstrom, alpha= 71.110(5)degrees beta = 79.99 0(5)degrees gamma = 89.470(5)degrees, Z = 1). Its structure comprises neutr al trinuclear bimetallic complexes in which a central [Fe(CN)(5)NO](2-) ani on is linked to two [Mn(3-MeOsalen)](+) cations. 4 crystallizes in the tetr agonal space group P4/ncc (a = 13.630(5) Angstrom, c = 21.420(8) Angstrom, Z = 4). Its structure shows an extended 2D neutral network formed by cyclic octameric [-Mn-NC-Fe-CN-](4) units. The magnetic properties of these compo unds indicate the presence of quasi-isolated paramagnetic Ni2+ and Mn3+. Ir radiated samples of the four compounds have been studied by differential sc anning calorimetry to detect the existence of the long-lived metastable sta tes of nitroprusside.