Crystal and anion structure, TGA, DTA, and infrared and Raman spectra of manganese(II) nitroprusside dihydrate, Mn[Fe(CN)(5)NO]center dot 2H(2)O

The single crystal and anion structure of Mn[Fe(CN)(5)NO . 2H(2)O, obtained by slow interdiffusion of reactant solutions through a TMS gel, was solved by X-ray diffraction methods and refined to R1 = 0.036. Spatial group: orthorhombic, Pnma, a = 14.069(2), b = 7.538(1), c = 10.543(1)Angstrom, Z = 4. The Mn(II) ion and the water molecules are sited on mirror planes, which bisect the nitroprusside ions. One of the water molecules is coordinated to Mn(II) and the other, strongly hydrogen (as acceptor) bonded to the first molecule. The IR spectrum confirms the bonding of the water molecules and TGA results are in accordance with the dihydrate character of the substance and its dehydration in two successive steps. DTA results and the Raman spectrum agree with other results and the comparison between IR and Raman nu NO wavenumbers confirms the expected strong vibrational interaction between the closely packed antiparallel (eclipsed) NO groups. There is a topotactic relationship between the dihydrate and the trihydrate, which crystallizes in the space subgroup P2(1)/n.