Manoranjan Das

Metal chelates of dithiocarbazic acid and its derivatives. IX. Metal chelates of ten new schiff bases derived from S-methyldithiocarbazate

The Schiff bases RR′CNNHC(S)SCH3 derived from S-methyldithiocarbazate have been prepared. The mass spectra of the Schiff bases having R = Me and R′ = Ph, 2-furyl, and 2-thienyl and R = R′ = Ph are similar and display strong peaks for the molecular ion M and the ions MCH3S, MCH3SH, R′CNH, R′CN, R′H, R′, and R′H. A mechanism of fragmentation is proposed. Complexes of the Schiff bases of the type Met(RR′CNNCSSCH3)2 (MetNi, Cu, Zn, Pd, and Pt) have been isolated in most instances. When R′ = Bun or Bui, nickel ion catalyses the hydrolysis of the Schiff base with the concomitant formation of the S-methyldithiocarbazate complex [Ni(H2NNHCSSCH3)3](NO3)2. The metal complexes are being tested for anti-cancer activity.

A comparative 13C and 19F NMR study of some nickel, zinc and cobalt monothio-β-diketonate complexes

Abstract The 13 C and 19 F NMR spectra of the nickel, zinc and cobalt complexes of 1,1-difluoro-4-mercapto-4-(2′-thienyl)but-3-en-2-one, 1,1,1-trifluoro-4-mercapto-4-(2′-thienyl)but-3-en-2-one and 1,1,1-trifluoro-4-mercapto-4-(2′-naphthyl)but-e-en-2-one are reported. The nickel and zinc complexes have a cis -square planar, and tetrahedral geometry, respectively. Our NMR data support a facial ( cis ) octahedral geometry for the cobalt complexes. The high and low frequency IR spectra of the zinc complexes show a small variation in the diketone ring vibrations with thienyl or naphthyl substituents. The 19 F NMR spectra show the chemical shift of the trifluoromethyl group to be metal dependent.

Tris(trifluoro and difluorobutane-2,4-dionato)aluminum(III) complexes

Eight tris(β-diketonate)aluminum(III) complexes having various fluoro and aryl substituents have been studied by nuclear magnetic resonance spectroscopy. The complexes are all nonrigid (fluxional) and their 19F nuclear magnetic resonance spectra show four resonances in the nonexchanging region due to cis and trans isomers. A variable high temperature 19F NMR study of these complexes was done and activation parameters are calculated.

Dipole moments of some metal complexes of six new monothio-β-diketones containing perfluoroalkyl group

Abstract Dipole moments of nickel(II), palladium(II) and cobalt(III) complexes of six new monothio-β-diketones R 1 C(SH) = CHCOR 2 (R 1 = phenyl, 2′-naphthyl and 2′-thienyl; R 2 = C 2 F 5 and CF 2 CF 2 CF 3 ) were determined by static-polarization measurements. With same R 2 the dipole moments varies when R 1 arranged as 2′-thienyl > 2′-naphthyl > phenyl. With same R 1 the dipole moments varies as C 3 F 7 > C 2 F 5 . The latter values are small: 0.03–0.37 D for the nickel, 0.08–0.24 D for the palladium and 0.12–0.16 D for the cobalt complexes. Nickel(II) and palladium(II) complexes definitely have cis -square-planar structures Cobalt(III) complexes perhaps have the facial -octahedral configurations.

Dipole moments and mass spectra of some metal complexes of three new monothio-β-diketones, RCSCH2COCHF2

SummaryThe dipole moments of some nickel(II), copper(II), zinc(II) and cobalt(III) complexes of three new difluoro monothio-β-diketones RCSCH2COCHF2 (R = 2-thienyl, phenyl andp-tolyl) have been determined by static polarization measurements. The mass spectra of these complexes are discussed. The mass spectra of nickel complexes of the correspondingβ-diketones are also presented for the purpose of comparison.

13C and 19F nuclear magnetic resonance studies on some monothio-β-diketonate complexes

Abstract The 13 C and 19 F NMR spectra of nine metal complexes containing trifluoromethylmonothio-β-diketonate ligands are recorded in chloroform-d. The complexes are of the type M(RC(S)CHC(O)CF 3 ] n where n is 2 or 3; M is zinc, platinum, cobalt or nickel and R is 4-C 2 H 5 C 6 H 4 , 4-C 2 H 5 OC 6 H 4 , 3, 4, 5-(CH 3 O) 3 C 6 H 2 or 3, 5-(CH 3 O) 2 C 6 H 3 . The cobalt complexes (CoL 3 ) have a cis -octahedral configuration in solution. 13 C- 195 Pt spin coupling is observed for the platinum complex. The 19 F NMR spectra show the chemical shift of the trifluoromethyl group to be dependent on the metal.

Dipole-moment measurements on metal chelate complexes. Part 1. Dipole-moment and dielectric-relaxation measurements on square-planar and octahedral metal complexes of seven mercapto-β-diketones

Dipole moments have been determined for iron(III), cobalt(III), nickel(II), palladium(II), platinum(II) and copper(II) complexes of the mercapto-β-diketones RC(SH):CH·C(O)R′[R = Me or Ph, R′= Ph; R = Me, C4H3S (2-thienyl), Ph. p-MeC6H4, or p-BrC6H4, R′= CF3] from both static-polarization and dielectric-relaxation measurements. The moments clearly indicate cis-square-planar configurations for the nickel, palladium, platinum, and copper complexes, but do not distinguish unequivocally between facial- and meridional-octahedral configurations for the iron and cobalt complexes. Group dipole moments for the R substituents, except 2-thienyl, in the square-planar complexes have been derived from the dipole-moment data. The effect of the CF3 group is discussed in terms of its influence on the electron density in the chelate ring.

Tris(difluoro and trifluorobutane-2,4-dionato) gallium(III) and indium(III) complexes

Abstract Eight tris (β-diketonate)gallium(III) and seven tris (β-diketonate)-indium(III) complexes M(RCOCH-COR′) 3 , with R′being difluoromethyl and trifluoromethyl substituents and R′ being methyl, phenyl, aryl, 2′-naphthyl and 2′-thienyl substituents have been studied by nuclear magnetic resonance spectroscopy. The complexes are all nonrigid (fluxional) and their 19 F NMR spectra show four resonances in the nonexchanging regions due to cis and trans isomers. A variable low temperature study of these complexes was done for the gallium chelates and activation parameters are calculated. The indium complexes all have nonexchanging regions below −100°C. The 13 C NMR data on the complexes are also reported.

NMR studies of some second and third row transition metal complexes of monothio-β-diketones

Abstract A 13 C and 19 F NMR study of twenty-four ruthenium, rhodium, palladium and platinum complexes containing a difluoromethyl or a trifluoromethyl substitutent(R′) on the monothio-β-diketone, RCSCH 2 COR′, is reported. The R-substituents are 2′-thienyl, 2′-naphthyl, phenyl, p-fluorophenyl or p-methylphenyl. The 13 C NMR data show the chemical shift of the diketonate ring carbons to be geometry dependent. Similarly, the 19 F NMR spectra show chemical shift data which are also metal dependent. The thiocarbonyl and methine carbons shieldings are also dependent on the nature of the R-group. The rhodium and platinum complexes show carbon-metal and carbon-fluorine spin coupling. The paramagnetic ruthenium(III) complexes give 19 F NMR spectral resonances which are broad and shifted upfield from the corresponding diamagnetic rhodium, palladium and platinum complexes. 13 C and 19 F NMR data supports a facial octahedral geometry for the rhodium(III) complexes.

A NMR spectroscopic study of some monothio-β-diketonate chelates and the corresponding β-diketones with a perfluoroethyl substituent

Abstract The 13 C and 19 F NMR of nine metal complexes contained perfluoroethylmonothio-β-diketonate ligands are recorded in chloroform- d . The complexes are of the type M[RC(S)CHC(O)C 2 F 5 ] n where M is of nickel, palladium or cobalt; n is 2 or 3 and R is 2′-thienyl, phenyl or 2′-naphthyl. The 13 C-NMR data support a fac -octahedral geometry for the cobalt complex ( n =3). The 19 F NMR show the chemical shift of the difluoromethylene group to be metal dependent. Correlations between the chemical shifts of the respective carbon resonances are also presented and NMR data for the three corresponding β-diketones, RC(OH) = CHC(O)C 2 F 5 , are described.