X-Ray Diffraction Study of the Solvation Structure of the Cobalt(II) Ion in N,N-Dimethylformamide Solution

Abstract

X -R a y D if fr a c tio n S tu d y o f th e S o lv a tio n S tr u c tu r e o f th e C o b a lt ( I I ) I o n in N ,N -D im e th y lf o rm a m id e S o lu tio n Haruhiko Yokoyama*, Saeko Suzuki*, Masuo Goto*, Kazuteru Shinozaki*, Yuriko Abe**, and Shin-ichi Ishiguro*** * Department of Chemistry, Yokohama City University, Seto, Kanazawa-ku, Yokohama 236, Japan ** Department of Chemistry, Faculty of Science, Nara Women's University, Kita-uoya-nishi-machi, Nara 630, Japan *** Department of Chemistry, Faculty of Science, Kyushu University, Hakozaki, Higashi-ku, Fukuoka 812, Japan Z. Naturforsch. 50a, 301-306 (1995); received September 28, 1995 Dedicated to Prof. Hitoshi Ohtaki on the occasion of his 60th birthdayThe solvation structure of Co2+ in N,N-dimethylformamide (DMF) has been studied by X-ray diffraction measurements on cobalt (II) and magnesium (II) Perchlorate solutions of the same concen tration, using an isostructural substitution method. The radial distribution function revealed three distinct peaks assigned to the oxygen, amido carbon (CJ, and nitrogen atoms of six planar DMF molecules in the first coordination sphere around the metal atom. The distance from the cobalt atom to each atom (O, Cx, N) is 213,299, and 423 pm, respectively. This indicates that the Co-O-Cj bond angle is 122-123° and the metal atom is close to the O-Cj-N plane of the DMF molecule.

Electrochemistry of Oxygenation Catalysts. 3.1 Thermodynamic Characterization of Electron Transfer and Solvent Exchange Reactions of Co(salen)/[Co(salen)]+ in DMF, Pyridine, and Their Mixtures

“…Often, pentacoordinated Co II (salen)-type complexes are formulated, which reflects results of X-ray analyses , and ESR spectroscopy, , the latter in solutions with only a small amount of base present (toluene + 1% py). On the other hand, Co(II) was characterized in neat DMF solution as being coordinated by six DMF molecules, and complexes structurally similar to 1 have been formulated in hexacoordinate form . Recently, equilibria between penta- and hexacoordinated macrocyclic complexes of Co(II) have been invoked to explain electrochemical results …”

Structure of Solvation Sphere of Tris(acetylacetonato)chromium(III) in Acetonitrile

“…In the present study, the change of the effective scattering angle from the geometrical one due to the low absorption of solutions was corrected by estimating the position giving half of the observed scattering intensity. After the absorption correction, the diffraction intensity data were treated by a version of the KURVLR program modified for use on an IBM personal computer. , …”

“…B. X-ray Diffraction on Isostructural Solutions of Metal Complexes. Radial distribution functions were derived according to the manner previously described. , The experimental radial distribution function, D ( r ), involving all two-atoms correlations in solution was obtained by where ρ 0 = (∑ n i Z i ) 2 / V , s = 4π(sinθ)/λ, i ( s ) is the reduced intensity, and M ( s ) is the modification function with the scattering factor of oxygen ( f o ) and a damping factor k = 0.01 × 10 -20 m 2 , that is, M ( s ) = ( f o (0)/ f o ( s )) 2 exp(− ks 2 ). n i is the number of atoms i with atomic number Z i in V , which is the stoichiometric unit volume including one complex molecule, and the other symbols have their usual meanings.…”

“…Tris(acetylacetonato)chromium(III) (Figure ), [Cr(acac) 3 ] (acac - = 2,4-pentanedionate ion), is chosen as the solute, because it is an inert, stable, and paramagnetic complex quite soluble in acetonitrile. Moreover, structurally very similar analogs of cobalt(III) and ruthenium(III) are available; the former is a good diamagnetic partner for NMR relaxation rate measurements, , and the latter serves as a suitable isostructural partner , for the isomorphous substitution technique of the solution X-ray diffraction method. , These molecules are almost spherical except for having five hollows (two along the C 3 axis and three along the C 2 axes). These hollows aside, the peripheries are hydrocarbons.…”

Solvation of alkaline earth metal ions in N,N -dimethylformamide and N,N -dimethylacetamide – A volumetric and acoustic study

“…It has been established that the zinc(II) ion is hexasolvated in dmf, whereas in dma solution it has an average solvation number of 4.6 [26]. In contrast, the magnesium(II) ion is six-coordinate in both dmf and in dma [27]. Thus, these facts imply that the partial molar volume cannot be simply determined by the size of ions only, as the solvation structure of the ion has to be taken into account.…”