Showing papers by "M. Salah El Fallah published in 2001"
TL;DR: A general formula for the magnetic susceptibility of the isotropic ferro-ferromagnetic S = 1 Heisenberg chain is developed in terms of the alternation parameter alpha (= J2/J1); this assumed a variation of chi(M)T versus the length N.
Abstract: Three new one-dimensional nickel(II) complexes with the formulas trans-[Ni(N-Eten)2(mu1.3-N3)]n(ClO4)n (1), trans-[Ni(N-Eten)2(mu1.3-N3)]n(PF6)n (2), and cis-[Ni(N-Eten)(mu1.1-N3)2]n (3) (N-Eten = N-Ethylethylenediamine) were synthesized and characterized. Complex 1 has the P2(1)/c space group and consists of a structurally and magnetically alternating one-dimensional antiferromagnetic system with end-to-end azido bridges. Compound 2 has the P1 space group and has alternate units in its structure but consists of a magnetically uniform one-dimensional antiferromagnetic system with end-to-end azido bridges. Complex 3 has the I2/a space group and may be described as a structurally and magnetically alternating one-dimensional ferromagnetic system with double azido bridged ligands in an end-on coordination mode. The chi(M)T versus T plots for compound 3 suggest an intramolecular ferromagnetic interaction between adjacent NiII ions and metamagnetism at low temperature (below 10 K). The magnetization measurements versus applied field confirm this metamagnetic ordering. In order to describe the magnetic data of this compound we developed a general formula for the magnetic susceptibility of the isotropic ferro-ferromagnetic S = 1 Heisenberg chain in terms of the alternation parameter alpha (= J2/J1); this assumed a variation of chi(M)T versus the length N.
63 citations
TL;DR: In this article, two new copper(II) complexes with pseudohalide ligands have been synthesized and their crystal structures have been determined by X-ray diffraction: a dinuclear complex [Cu2(μ1,1-NCO)2(NCO),2(phen)2] (1) in which two cyanate ligands formed an end-on bridge between the two copper (II) atoms and the two other act as terminal ligands, and a mononuclear complex {[Cu(meso-cth)(CN)]ClO
35 citations
TL;DR: In this paper, a new complex of formula {[Cu(L)][Cu (L)Cr(CN)6]ClO4·2H2O}n1 (L is meso-5,5,7,12, 12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) has been prepared from the reaction of [Cr[CN]3− and [Cu[L]2+, and its structure and magnetic properties studied.
Abstract: A new complex of formula {[Cu(L)][Cu(L)Cr(CN)6]ClO4·2H2O}n1 (L is meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) has been prepared from the reaction of [Cr(CN)6]3− and [Cu(L)]2+, and its structure and magnetic properties studied. The structure consists of a discrete [Cu(L)]2+ cation and an anionic fragment formed by [Cu(L)Cr(CN)6]− in which the CuII is coordinated to four N atoms of the macrocycle and two CN groups of the hexacyanometalate in trans positions to give a one-dimensional compound. The compound shows a moderate ferromagnetic coupling. In order to describe its magnetic data a new formula was developed for the magnetic susceptibility of an isotropic ferromagnetic S = 1/2 and 3/2 Heisenberg chain assuming a variation of χMTvs. the length N. The best least-squares fit gives J = 4.82 cm−1, g = 2.02 and R = 1.23 × 10−4.
32 citations