K.S. Patel

Infrared spectra of N,N′-bis(salicylidene)-1,1-(dimethyl)ethylenediamine and its metal complexes

Abstract I.R. spectra in the region 4000-400 cm −1 have been recorded for N,N′-bis(salicylidene)-1,1-(dimethyl)ethylenediamine(Sal 2 -i-bn) and its complexes with divalent nickel, cobalt, copper and palladium. Assignments of the observed frequencies have been made to specific group vibrations by comparison with the spectra of related compounds. Effect of chelation on the ligand group frequencies and the stability order of the chelates are also discussed.

Physicochemical studies of metal haloacetates—V Magnetic and spectral studies of copper(II) fluoroacetates

Abstract The fluoroacetates of copper(II) have been prepared and their magnetic and spectral properties examined. The hydrated monofluoroacetate is essentially a dimer with a J value of 354 cm − , while anhydrous monofluoro- and difluoroacetates appear to be a mixture of dimeric and poly- or monomeric forms. The anhydrous trifluoroacetate and the hydrated difluoro- and trifluoroacetates do not assume the binuclear configuration and are likely to be polymeric.

Physico-chemical studies of metal β-diketonates—I Infrared spectra of 1-(3-pyridyl)-1,3-butanedione and its divalent metal complexes

Abstract The i.r. spectra of 1-(3-pyridyl)-1,3-butanedione (nicotinylacetone) and its complexes with divalent Be, Mn, Co, Ni, Cu, Zn and Pd have been measured between 4000 and 300 cm−1. Substitution of a methyl group in the acetylacetonate by a pyridyl ring has been found to strengthen the CO and MO bonds and weaken the CC bond of the chelate ring. The stability of these complexes is discussed in relation to the chelate ring vibrational frequencies.

Physicochemical studies of metal β-diketonates—V: Spectral and magnetic properties of the Al(III), Cr(III), Mn(III), Fe(III) and Co(III) complexes of 1-(2-thienyl)-1,3-butanedione and 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione

Abstract The spectroscopic and magnetic properties of trivalent metal complexes of 1-(2-thienyl)-1,3-butanedione (Htbd) and 4,4,4 - trifluoro - 1 - (2 - thienyl) - 1,3 - butanedione (Htftbd) (where M(III) = (Al, Cr, Mn, Fe, Co) have been examined. The IR band assignments suggest that substitution of a trifluoromethyl group in thenoylacetone for a methyl one increases the CO and CC bond strengths and decreases that of MO bond of the chelate ring. The spectral and magnetic properties of these two series of complexes revealed that they are very similar to the corresponding tris-(2,4-pentanedionato) M(III) complexes.

Low-frequency infrared spectra of crystalline copper(II) acetate and its chloro derivatives

Abstract The i.r. spectra of copper(II) acetate and its mono-, di- and trichloro derivatives have been measured from 525-40 cm −1 . Some frequency assignments are proposed for CuO stretching vibrations between 300–400 cm −1 . Attempts have also been made to correlate the CuO frequencies with the structures of the complexes.

Physicochemical studies of metal β-diketonates—III magnetic and spectral properties of the manganese(II), iron(II), cobalt(II), nickel(II), copper(II), zinc(II) and palladium(II) complexes of 1-(3-pyridyl)-1,3-butanedione and 4,4,4-trifluoro-1-(3-pyridyl)-1,3-butanedione

Abstract The magnetic properties of bis[1-(3-pyridyl)-1,3-butanedianato] M(II) and bis[4,4,4-trifluoro-1-(3-pyridyl)-1,3-butanedianato] M(II) (where M = Mn, Fe, Co, Ni, Cu, Zn, Pd) have been investigated over the temperature range 300−82°K. Magnetic moments indicate that these complexes are polymeric and of mostly magnetically diluted systems. The electronic spectra of these compounds have been examined at room temperature and 77°K and the tentative band assignments have been made. This evidence suggested that though their stereochemistries could be similar to the corresponding bis-(acetylacetonato) M(II) complexes, they have stronger forces of association probably due to the interaction of nitrogen atoms of the pyridyl groups with the metal atoms.

Physicochemical studies of metal haloacetates—VII magnetic and IR studies of copper(II) bromo- and iodoacetates

Abstract The bromo- and iodoacetates of copper(II) have been prepared and their magnetic properties examined between 80 and 300°K. The hydrated and anhydrous monobromo-, monoiodo- and diiodoacetates appear to be essentially dimeric with a slight contamination by a monomer or polymer. Hydrated dibromoacetate and anhydrous di- and tribromoacetates occur in more than one form, while the hydrated tribromoacetate is monomeric.

Physico-chemical studies of metal β-diketonates—II Infrared spectra of 4,4,4-trifluoro-1-(3-pyridyl)-1,3-butanedione and its divalent metal complexes

Abstract The divalent metal complexes of Mn, Co, Ni, Cu, Zn and Pd with 4,4,4-trifluoro-1(3-pyridyl)-1,3-butanedione have been prepared for the first time. The i.r. spectra including that of beryllium chelate are measured between 4000 and 300 cm −1 and assignments are proposed for the observed frequencies. Trifluoromethyl substitution in nicotinylacetonates is found to increase the CO and CC bond strengths and decrease that of MO bond. The magnitudes of CO and MO stretching frequencies follow very well the Irving-Williams stability order Pd> Cu > Ni > Co > Zn > Mn.

Physicochemical studies of metal β-diketonates—IV: Magnetic and spectral properties of divalent transition metal complexes of 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione

Abstract The complexes of 4,4,4 - trifluoro - 1 - (2 - thienyl) - 1,3 - butanedione (Htftbd) with some divalent metal ions of the formula [M(tftbd) 2 ] (M = Mn, Co, Ni, Cu, Zn, Pd) and [M(tftbd) 2 (H 2 O) 2 ] (M = Mn, Fe, Co, Ni, Zn) have been prepared and characterised using magnetic susceptibility measurements over the temperature range 300–380°K and reflectance electronic spectra. Though the magnetic and spectral properties of the hydrated and corresponding anhydrous chelates are similar, Mn(tftbd) 2 shows evidence of an antiferromagnetic interaction (θ = 32°) while Ni(tftbd) 2 provides an example of a ferromagnetic interaction (θ = −10°). The sulphur atoms of the thienyl rings do not bond to the metals, consequently, the stereochemistries of these complexes resemble very closely the corresponding acetylacetonates.