Mrinal K. Das

Synthesis and characterization of diorganotin(IV) complexes of tetradentate Schiff bases: Crystal structure of n-Bu2Sn(Vanophen)

Abstract Diorganotin(IV) complexes of the general formula R2SnL (R=Ph, n-Bu and Me) have been prepared from diorganotin(IV) dichlorides (R2SnCl2) and tetradentate Schiff bases (H2L) containing N2O2 donor atoms in the presence of triethylamine in benzene. The Schiff bases, H2L, were derived from salicylaldehyde, 3-methoxysalicylaldehyde (o-vanillin), 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone and diamines such as o-phenylenediamine and 1,3-propylenediamine. The complexes were characterized by IR, NMR (1H, 13C, 119Sn) and elemental analysis. The structure of the complex, n-Bu2Sn(Vanophen), was determined using single crystal X-ray diffraction. The tin atom has a distorted octahedral coordination, with the Vanophen ligand occupying the four equatorial positions and the n-butyl groups in the trans axial positions. Six-coordinated distorted octahedral structures have been proposed for all diorganotin(IV) complexes studied here, as they possess similar spectroscopic data.

Di- and triorganotin(IV) derivatives of N,N-substituted hydroxylamines

Abstract Twenty-four organotin(IV) N,N-disubstituted hydroxylamines of the formula R2SnL2 (R = n-C4H9 and C6H5; LH = N,N-disubstituted hydroxylamines) and (C6H5)3SnL (LH = as above) have been synthesized by the reaction of organotin(IV) chlorides and hydroxylamines in presence of triethylamine in benzene medium. UV, IR, NMR and Mossbauer spectroscopic techniques have been utilized for the characterization and elucidation of the structural and bonding aspects of the compounds. The results indicate that the di-n-butyltin(IV) bis(hydroxylaminates) have distored trans-octahedral structures, whereas the diphenyltin(IV) bis(hydroxylaminates) and triphenyltin(IV) hydroxylaminates are cis-octahedral and trigonal bipyramidal with equatorial triphenyltin groups, respectively.

STUDIES ON THE DIORGANOTIN(IV) COMPLEXES OF SOME DIHYDROXAMIC ACIDS

Abstract Twenty-one diorganotin(IV) complexes of N, N′-substituted dihydroxamic acids of the formula {R21Sn[ON(R)CO]2(CH2)n}2 (R1 = n-C4H9, C6H5; R = C6H5, 4-CH3C6H6H4, 4-ClC6H4) were synthesized by the reaction of diorganotin(IV) dichlorides and dihydroxamic acids in the presence of triethylamine. Molecular weight determinations and electronic, IR, Raman and NMR spectroscopic techniques were utilized for the characterization and elucidation of the structural and bonding aspects of the compounds. The results suggest that all the compounds are dimeric and the di-n-butyltin(IV) dihydroxamates have trans-octahedral structures, whereas the diphenyltin(IV) dihydroxamates have cis-octahedral structures.

Studies on some di- and triorganotin(IV) derivatives of bis(1-pyrazolyl) borates and some related compounds

Abstract A number of di- and triorganotin(IV) complexes of dihydrobis(1-pyrazolyl)borate and diphenylbis(1-pyrazolyl)borate have been synthesized. The complexes derived from dihydrobis(1-pyrazolyl)borate have been converted to their dihalobis(1-pyrazolyl)borate analogues by halogenation reactions. The compounds have been characterized by elemental analysis, infrared and 1 H, 11 B and 119 Sn NMR spectra.

Synthesis and Characterization of Some Phosphine-Boranes and Phosphine- and Phosphite-Cyanoboranes

Abstract Phosphine-boranes have been very conveniently prepared in high yields by the reaction of NaBH4 and I2 with the corresponding phosphine in refluxing tetra-hydrofuan. Phosphine- and phosphite-cyanoboranes have been prepared by the reaction of NaBH3CN with I2 with the corresponding phosphine or phosphite in refluxing monoglyme. All these compounds have been characterized by elemental analysis, IR spectra and proton NMR spectra.

Convenient and High-Yield Synthesis of Triphenylphosphine-Cyanoborane and -Dihaloboranes

Abstract Triphenylphosphine-cyanoborane has been very conveniently prepared in high yield by the reaction of NaBH3CN with triphenylphosphine hydrochloride in refluxing tetrahydrofuran, and triphenylphosphine-dichloro- and dibromoboranes have been prepared by halogenation of the precursor triphenylphosphine-borane with free halogen respectively in carbon tetrachloride and dichloromethane. These compounds were characterized by elemental analysis, and infrared and proton NMR spectra.

Preparation, characterization and Mössbauer spectra of the iron(III) complexes of some dihydroxamic acids and amino monohydroxamic acids

SummaryFeIII complexes have been prepared from the dihydroxamic acids (CH2)n[CON(R)OH]2 (n=2, 3, 4, 6, 8; R=H, Ph,o-tolyl,p-tolyl) (H2L) and the amino monohydroxamic acids H2NCH(R)CONHOH (R=H, Me) (HL′) and XC6H4CONHOH (X=o-NH2,p-NH2) (HL″). Based on elemental analyses, molecular weight data, and electronic and i.r. spectra, the complexes have been formulated as Fe2(LH)2L2, Fe2L2O and Fe2L3 for the dihydroxamic acids, and Fe(OH)4L′2(H2O)2 and FeL″3 for the amino monohydroxamic acids. The57Fe Mossbauer spectra are discussed.

Synthesis and characterization of pseudohaloborane adducts of some heteroaromatic N-bases

Abstract Six cyanoborane adducts of the heteroaromatic amines, 2-amino-, 3-amino-, 4-amino-, 2-amino-4- methyl-, 4-cyano- and 4-ethylpyridines, and four isothiocyanatoborane adducts of the heteroaromatic amines, 3-methyl-, 4-methyl-, 4-ethyl- and 4-amino- pyridines have been prepared. These have been characterized by elemental analyses and by infrared and 1H and 11B NMR spectral study.

N-benzoyl-o-tolylhydroxylamine as a gravimetric reagent for uranium(VI)

Abstract N-Benzoyl- o -tolylhydroxylamine has been used for the gravimetric determination of uranium(VI) by direct weighing of the complex. Uranium(VI) is precipitated quantitatively in the pH range 5.0–7.5 and its separation from a large number of metal ions is described. The composition of the complex has been formulated as UO 2 (C 14 H 12 O 2 N) 2 ·C 14 H 13 O 2 N in conformity with analysis, n.m.r. and mass spectra. The gravimetric factor for the conversion of the metal-complex to the metal is 0.2509, smaller than that for other reagents for uranium.

SYNTHESIS, SPECTROSCOPY AND STRUCTURE OF DIORGANOTIN(IV) SCHIFF BASE COMPLEXES

Three diorganotin(IV) chelates with a tetradentate Schiff base, H2Vanophen, [H2Vanophen = N,N′-1,2-phenylen-bis(3-methoxysalicylideneimine)] of the type R2Sn(Vanophen) (R = Ph: 1; R = n-Bu: 2; R = Me: 3) have been synthesized by the reaction of R2SnCl2 (R = Ph, n-Bu, Me) and H2 Vanophen in the presence of triethylamine in benzene. The complexes have been characterised by IR and NMR spectroscopy and by elemental analysis. The δ(119Sn) values for the complexes 1 - 3 are -543.0, -414.2 and -398.2 ppm respectively, indicating hexacoordinated Sn centers. These have been ascertained by X-ray crystal structure determinations of 1 and 3. The distances between tin and the two axial carbon atoms in each complex differ not significantly [2.17(1) Å in 1, and 2.100(3) and 2.115(3) Å in 3). The C-Sn-C angles for 1 and 3 are 165.9(4)° and 159.96(9)°, respectively. The solution NMR spectra (1H , 13C, 119Sn) show clearly that the solid state structures are retained in solution.