Chaurasia, Sheo Chandra

Maurya, Ram Charitra

Sarkar, Sabyasachi

English

NOPR

n-Glucuronic acid itself is not reduced at the d.m.e.but in aqueous solution it is converted into n-glu-curono-ti.Llactonew which is reduced in two steps.Limiting currents for both the lactone waves havebeen found to be linearly dependent on the concen-tration of n-glucuronic acid and hence can beutilized for analytical determination. PH of themedium has a marked effect on the magnitudes ofthe waves. Wave-heights decrease rapidly withincreasing PH of the medium. Two factors maybe responsible for this behaviour. Firstly, hydrogenions are involved in the reduction process. Andsecondly, in alkaline medium, n-glucuronic acidlargely forms n-glucuronate and not reduciblen-glucuronolactone.References1. ISHIDATE, M. & SHIMOZAWA, T., J. pbarm: Soc. Japan,64 (1944), 53.2. THIBERT, R. J. & BOYLE, A. J., T'alanta, 7 (1961), 175.3. THIBERT, R. J. & JOHNSTON, J. R., Can. J. cu«; 47(1969), 265.4. HEYROVSKY, J. & KUTA, J., Principles of polarography(Academic Press, New York), 1966.5. FEDoRo/rKo, M., in Advances in carbohydrate chemistryand biochemistry, Vol. 29, edited by R. S. Tipson &D. Horton (Academic Press, London), 1974, 107.Bis( acetylacetonato )ni trosyl Cr(I)SABYASACHI SARKAR, RAM CHARITRA MAURYA &SHEO CHANDRA CHAURASIADepartment of Chemistry, T.D. College, Jaunpur 222002Received 17 November 1975; accepted 24 December 1975A monomeric neutral Cr(l) complex, (Cr(acac).NO]has been prepared by the reaction of potassium penta-cyanonitrosylchromate (I) monohydrate with exces-of acetylacetone in the absence of air. The complexshows a magnetic moment of 1·72 B.M. and g value of1·982 consistenr with a low-spin d5 configuration ofCr (I). Its IR spectrum exhibits a very strong bandat 1692 em= which is characteristic of vNO+. On thebasis of IRand electronic spectral data, a square-pyramidal structure is proposed for the complex.AFTER the isolation of potassium salt of nitrosyl-pentacyanochromate (1)1, several other cationicnitrosyl complexes of hexacoordinated Cr(I)2.3havebeen reported. However, neutral complexes ofnitrosyl Cr(I) have not been reported so far. Inthis note we report the preparation and propertiesof bisiacetylacetonatojnitrosyl Cr(I), a neutral com-plex having comparable stoichiometry to that of[Co(acac)2NOJbut containing NO+group in contrastto NO- group present in the cobalt complex-.The complex was prepared by refluxing a mixtureof K3[Cr(CN),;NO]-H20(ref. 1) and excess acetyl-acetone in an air-tight compartment with an inter-mittent removal of the liberated HCN by passingdry CO2, After refluxing for 8 hr, the excess acetyl-acetone was distilled off and the resultant mixturewas cooled in vacuo over solid KOH. Traces ofNOTESfree acetylacetone were removed from the cooledbrown mass by repeated washing with petroleumether and the brown crust was extracted withacetone. On evaporation of acetone, the solutiongave brown crystals which were washed with petro-leum ether. The crystallization processwas repeatedthrice. The crystal thus obtained were dried andanalysed [Found: Cr, 18·6; N, 5·0; C, 42·9; H, 8·32;calc. for CrNO(acac)2: Cr, 18·6; N, 5·0; C, 42·9;H, 8'23%J; m.p. 2060; mol. wt 300 (Rast).This non-electrolytic monomeric complex (AM=13·2 0-1 cm2 mcle> in acetone) is soluble in mostof the common non-polar organic solvents butinsoluble in water. Its stability is comparableto that of Cr(acac)a as it remains unaffected byconcentrated alkalies or mineral acids in cold. anddecomposes only on prolonged boiling. The roomtemperature magnetic moment (1'72 B.M.) is con-sistent with a low spin d5 configuration (g= 1·982).Its IR spectrum shows a very strong band at ~1692cm! characteristic of v (NO+) (ref. 5). The lowenergy vibrations in the range 700-385 crrr- consistof three envelopes. The first one contains sharpbands at 675, 654 and 640 cm-I, the second at 610and 592 cm-1and the third one at 454 and 412 em"!respectively. The nature of the first and thirdenvelopes are identical to that observed by Mikamiand coworkers" for several square-planar acetyl-acetonato complexes of bivalent metals. The bands.in second envelope, then, should be due to Cr-Nstretching and Cr-N-O bending vibrations respec-tively as reported by Miki", The solid state andsolution (ethanoh electronic spectra give four ab-sorptions at identical positions, viz. 18·] 8 (32),25·38 (135), 29·65 (3120), and 39·22 (1900) (peakpositions in kK and molar extinction coefficientsin parentheses) suggesting that solvation does nottake place at the sixth position. On the basis ofabove data, a square-pyramidal structure may beproposed for the complex. First two of the aboveelectronic transitions are believed. to be of ligandfield origin while the third and fourth peaks canbe assigned to strong 1t-1t* transitions of the com-plexed acetylacetone moietys-".We are indebted to Prof. R. P. Rastogi, GorakhpurUniversity and Dr P. K. Singh, Principal, fortheir encouragement and help.References1. GRIFFITH, W. P., LEWIS, J. & WILKINSON, G., }. chem:Soc., (1959), 872.2. GRIFFITH, W. P., J. chem, Soc., (1963), 3286.3. FELTHAM, R. D., SILVERTHORN, W. & Me PHERSON, G.,Inorg. Chem., 8 (1969), 844.4. NAST, R. & BIER, H., Chem. Ber., 92 (1959), 1858; MeBRIDE, D. W., STAFFORD, S. L. & STONE, F. G. A.,Inorg. cu«; 1 (1962), 386.5. JOHNSON, B. F. G. & MCCLEVERTY, J. A., in Pro-gress in inorganic chemistry, Vol. 7, edited byF. A. Cotton (John Wiley, New York), 1966, 277-279.6. MIKAMI, H., NAKAGANA, I. & SHIMANOUCHI, T., Spectro-chim. Acta, 23A (1967). 1037.7. MIKI, E., Bull. chem. Soc. Uapan) , 41 (1968), 1835.8. ENEMARK, J. H. & FELTHAM, R. D., J. Am. chem. Soc.;96 (1974), 5002, 5004.9. FACKLER (Jr), J. P., Progress in inorganic chemistry,Vol. 7, edited by F. A. Cotton (John Wiley, NewYork), 1966, 372.285

Bis(acetylacetonato)nitrosyl Cr(I)

http://nopr.niscair.res.in/bitstream/123456789/53656/1/IJCA%2014A%284%29%20285.pdf

Bis(acetylacetonato)nitrosyl Cr(I)

Abstract

Similar works

Full text

Available Versions

NOPR