A Mixed Cation Ternary Nitroprusside: [(CH 3 ) 4 N][Na][Fe(CN) 5 (NO)].2.5H 2 O (original) (raw)
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Polyhedron, 2002
18 / Abstract / 19 / / 20 / The crystal structure of nitropentaamminecobalt(III) nitroprusside sesquihydrate, [Co(NH 3 ) 5 NO 2 ][Fe(CN) 5 NO] ×/1.5H 2 O has / 21 / been determined by Patterson and Fourier methods employing 3881 independent X-ray reflections with I /2s (I ) and refined by / 22 / full-matrix least-squares to R 1 0/0.032. The substance crystallizes in the monoclinic C 2/c (C 2h 6 ) space group No. 15, with a 0/ / 23 / 28.408(3), b 0/6.422(1), c 0/22.401(3) Å , b 0/123.55(1)8 and Z0/8. The metastable state I (MSI) of the nitroprusside anion and the / 24 / photochemical isomerization reaction of the nitropentaamminecobalt(III) cation to the nitrito isomer were produced by irradiation / 25 / with Ar ' laser light of 488 nm wavelength at 77 K. TGA and DTA of the non-excited substance were performed under nitrogen / 26 / atmosphere. # 2002 Published by Elsevier Science Ltd. / 27 / Keywords: PPPPentacyanonitrosylferrate(2(/) ion; Metastable excited states; X-ray diffraction; FIRRS; TGA; DTA / 28 / 1. Introduction / 29 / An extensive work on nitroprussides, which includes / 30 / alkaline, alkaline-earth, and transition metals salts has / 31 / been previously performed ([1 Á/10] and references / 32 / therein). These studies provided interesting results, / 33 / especially about the vibrational and photophysical NO / 34 / behavior. The strongly polar NO stretching vibration / 35 / proved to be largely affected by the environment, as / 36 / suggested by resonant (interanionic) ([10] and references / 37 / therein) and non-resonant (lattice) effects experienced / 38 / by this stretching mode in salts containing the / 39 / [Fe(CN) 5 NO] 2( (NP) anion. [9,11] The MNO group, / 40 / in this and other pentaligandnitrosyl anions, [12 Á/17] / 41 / seems to be the site of the generation of two very long-/ 42 / lived metastable states (MSI and MSII) by irradiation at / 43 / low temperature with light in the 300 Á/550 nm wave-/ 44 / length range. A geometrical interpretation has been / 45 / proposed for MSI and MSII with a nearly linear / 46 / structure (FeON) for MSI and T-shaped Fe N O for MSII / 47 / [18] as results of very refined single crystal X-ray / 48 / diffraction studies. Recently, additional information / 49 / was obtained in favor of the linear, isonitrosyl structure / 50 / of MSI from the IR studies of 15 NO, N 18 O and 54 Fe-/ 51 / substituted excited sodium nitroprusside dihydrate / 52 / (SNP) and a DFT vibrational calculation [19].
The structure of two orthorhombic nitroprussides: Cd[Fe(CN)5NO]·2H2O and Zn[Fe(CN)5NO]·2H2O
Polyhedron, 2001
When zinc and cadmium nitroprussides, obtained as powders or single-crystals samples, are aged in air they lose crystallization water and change their crystalline structure. In the stable form these two complexes are orthorhombic dihydrates with four molecules in the unit cell. In the aging process the crystals become brittle producing a polycrystalline material. The crystalline structure of these two complexes (orthorhombic dihydrates) was refined from their XRD powder patterns using the Rietveld method. As the starting model in the refining process the reported orthorhombic structure of copper nitroprusside (dihydrate) was used. The main changes in the dehydration process associated with the structural transformation take place in the coordination sphere of the outer cation (Cd or Zn).
Structure of calcium nitroprusside tetrahydrate
Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 1980
mm-1 (Mo Ka), F(000) = 324. The structure was solved by the heavy-atom method. A full-matrix least-squares refinement proceeded to R = 0.041 for 1966 unique reflections (Rsy m "-0.021) measured by counter methods. An antiparallel alignment of the NC dipoles along b was observed as well as seven-coordinated Ca 2÷ ions. Introduction. The determination of the structure of the title compound was undertaken as part of a series of chemical, spectroscopic, TGA-DTA and structural studies of alkaline-earth nitroprussides (Lanfranconi,
Journal of Chemical Crystallography - J CHEM CRYSTALLOGRAPHY, 2001
The crystal structure of tetrabutylammonium nitroprusside dihydrate (TBANPDH, [(C4H9)4N]2[Fe(CN)5NO]·2H2O) was determined by single crystal X-ray diffraction (XRD) and the compound was also studied, as well as the anhydrous salt (TBANP), by room and low temperature Fourier Transform Infra-Red (FTIR) and room temperature Fourier Transform Near Infra-Red Raman (FTNIRR) spectroscopies. In addition to the ground states (GS), the metastable excited states (MSI and MSII) generated by laser excitation (488 nm) at low temperature were IR studied, both of the dihydrate and the anhydrate. TBANPDH crystallizes in the trigonal space group P3221, D63, with a = b = 13.777(2), c = 22.039(2) Å, and Z = 3. The structure was solved employing 1273 independent XR reflections, with I > 2s(I), by Patterson and Fourier methods and refined by full-matrix least-squares to R1 = 0.054.
Inorganic Chemistry, 2005
The kinetics and mechanism of the thermal decomposition of the one-electron reduction product of [Fe(CN) 5 NO] 2-(nitroprusside ion, NP) have been studied by using UV−vis, IR, and EPR spectroscopy and mass-spectrometric and electrochemical techniques in the pH range of 4−10. The reduction product contains an equilibrium mixture of [Fe(CN) 4 NO] 2and [Fe(CN) 5 NO] 3ions. The first predominates at pH <8 and is formed by the rapid release of trans-cyanide from [Fe(CN) 5 NO] 3-, which, in turn, is the main component at pH >9−10. Both nitrosyl complexes decay by first-order processes with rate constants around 10-5 s-1 (pH 6−10) related to the dissociation of NO. The decomposition is enhanced at pH 4 by 2 orders of magnitude with protons (and also metal ions) favoring the release of cyanides from the [Fe(CN) 4 NO] 2ions and the ensuing rapid delivery of NO. At pH 7, an EPR-silent intermediate I 1 is detected (ν NO , 1695 and 1740 cm-1) and assigned to the trans-[Fe II (CN) 4 (NO) 2 ] 2ion, an {Fe-(NO) 2 } 8 species. At pH 6−8, I 1 induces a disproportionation process with formation of N 2 O and the regeneration of nitroprusside in a 1:2 molar ratio. At lower pHs, I 1 leads, competitively, to a second paramagnetic (S) 1/2) dinitrosyl intermediate I 2 , [Fe(CN) 2 (NO) 2 ] 1-, a new member of a series of four-coordinate {Fe(L) 2 (NO) 2 } complexes (L) thiolates, imidazole, etc.), described as {Fe(NO) 2 } 9. Other decomposition products are hexacyanoferrate(II) or free cyanide, depending on the pH, and precipitates of the Prussian-Blue type. This study throws light on the conditions favoring rapid release of NO, to promote vasodilatory effects upon NP injection, and describes new processes related to dinitrosyl formation and NO disproportionation, which are also relevant to the diverse biological processes associated with NO and N 2 O processing.
Organometallics, 1992
Treatment of the dihalo nitrosyl complexes of molybdenum and tungsten, Cp'M(NO)X2 (Cp' = Cp (q5-C5H5), Cp* (q5-C5Me5); M = Mo, W; X = C1, Br, I), in CH3CN with NO+ or Ag+ salts affords a series of new diamagnetic cationic nitrosyl complexes, [Cp*Mo(NO)(NCCH3),12+ and [Cp'M(NO)X(NCCH,)?]+. Eight such complexes have been isolated analytically pure as either their PFsor BF4salts by crystallization from CH3CN/Eh0. The physical and spectroscopic properties of these organometallic cations are consistent with their possessing four-legged piano stool molecular structures. This conclusion has been confirmed by single-crystal X-ray crystallographic analyses of [Cp*Mo(NO)(NCCH,),] [PF& and [CpMo(NO)Cl-(NCCH3)2]BF4 which also establish that the acetonitrile ligands are coordinated linearly through their N atoms to the metal centers. Crystal data for [C~*MO(NO)(NCCH~)~I[PF~]~: monoclinic, a = 32.468 (4) A, b = 7.7966 (8) A, c = 10.2999 (17) A, B = 94.201 (9)O, 2 = 4, space group R 1 / a , number of unique reflections 5154, number of variables 325, RF = 0.048, RwF = 0.066. Crystal data for [C~MO(NO)C~(NCCH,)~]BF~: monoclinic, a = 8.4885 (8) A, b = 16.5569 (19) A, c = 10.3467 (15) A, / 3 = 91.753 (9)O, 2 = 4, space group P21/c, number of unique reflections 4101, number of variables 181, RF = 0.039, RwF = 0.059. lH NMR spectroscopy has been employed to demonstrate that the CH3CN ligands in the [C~*MO(NO)(NCCH,),]~+ complex are labile and undergo facile exchange with free CD3CN solvent molecules. Treatment of [CpCr(NO)I], with AgPF6 in CH3CN affords the novel paramagnetic complex [CpCr(NO)(NCCH3)2]PF,. The organometallic cation in this salt is monomeric in the solid state and possesses a three-legged piano stool molecular structure whose intramolecular dimensions have been determined crystall aphically. Crystal data for [CpCr(NO)(NCCH3)2]PF6: orthorhombic, a = 12.982 (4) A, b = 6.2962 (6) rc = 18.459 (2) A, 2 = 4, space group PnaP1, number of unique reflections 1377, number of variables 189, RF = 0.034, RwF = 0.044. The room-temperature ESR spectrum of [CpCr(NO)(NCCH3),]PF6 in DMF consists of a broad three-line pattern indicative of the unpaired electron in the 17-electron cation being primarily delocalized onto the nitrosyl ligand (a(I4N) = 5.21 G).