Co[(CH3PO3)(H2O)] (1) and Co[(C2H5PO3)(H2O)] (2) were prepared by the hydrothermal method and isolated as blue-violet platelet crystals. They were characterized by X-ray diffraction, FT-IR, TGA-DSC techniques and their magnetic properties studied by a dc-SQUID magnetometer. Compound (1) shows an hybrid layered structure, made of alternating inorganic and organic layers along the a-direction of the unit cell. The inorganic layers contain Co(II) ions six-coordinated by five phosphonate oxygen atoms and one from the water molecule. These layers are separated by bi-layers of methyl groups and van der Waals contacts are established between them. In compound (2), the layered hybrid structure is rather similar to that described for compound (1), but the alternation of the inorganic and organic layers is along the b-direction of the unit cell. The magnetic behavior of (1) and (2) as function of temperature and magnetic field was studied. The compounds obey the Curie-Weiss law at temperatures above 100 K, the Curie C, and Weiss 0 constants for the methyl derivative being C = 3.36 cm3 Kmol-1 and 0 = -53 K and for the ethyl derivative C = 3.62 cm3 K mol-1and 0 = -75 K, respectively. The observed magnetic moments for Co atom at room temperature (i.e. μeff = 5.18 and 5.38 BM, respectively) are higher than those expected for a spin-only value for high spin Co(II) (S = 3/2), revealing a substantial orbital contribution to the magnetic moment. The negative values of 0 are an indication of the presence of antiferromagnetic exchange couplings between the near-neighbors Co(II) ions, within the layers. [Co(CnH2n +1PO3)(H2O)] (n = 1,2) are 2D Ising antiferromagnets at low temperatures.

Co[(CH3PO3)(H2O)] (1) and Co[(C2H5PO3)(H2O)] (2) were prepared by the hydrothermal method and isolated as blue-violet platelet crystals. They were characterized by X-ray diffraction, FT-IR, TGA-DSC techniques and their magnetic properties studied by a dc-SQUID magnetometer. Compound (1) shows an hybrid layered structure, made of alternating inorganic and organic layers along the a-direction of the unit cell. The inorganic layers contain Co(II) ions six-coordinated by five phosphonate oxygen atoms and one from the water molecule. These layers are separated by bi-layers of methyl groups and van der Waals contacts are established between them. In compound (2), the layered hybrid structure is rather similar to that described for compound (1), but the alternation of the inorganic and organic layers is along the b-direction of the unit cell. The magnetic behavior of (1) and (2) as function of temperature and magnetic field was studied. The compounds obey the Curie-Weiss law at temperatures above 100 K, the Curie C, and Weiss 0 constants for the methyl derivative being C = 3.36 cm3 Kmol-1 and 0 = -53 K and for the ethyl derivative C = 3.62 cm3 K mol-1and 0 = -75 K, respectively. The observed magnetic moments for Co atom at room temperature (i.e. μeff = 5.18 and 5.38 BM, respectively) are higher than those expected for a spin-only value for high spin Co(II) (S = 3/2), revealing a substantial orbital contribution to the magnetic moment. The negative values of 0 are an indication of the presence of antiferromagnetic exchange couplings between the near-neighbors Co(II) ions, within the layers. [Co(CnH2n +1PO3)(H2O)] (n = 1,2) are 2D Ising antiferromagnets at low temperatures.

The ‘complexes as metal’ strategy has been used to prepare new mixed ligand complexes containing Co(II), Ni(II) and Cu(II) terpyridine (terpy) with dithiooxamide (dto) and thiosemicarbazide (tsc). Characterization of the complexes has been accomplished by elemental analysis, molar conductance, thermal analysis, as well as electronic and IR spectral measurements. It is deduced that the coordination mode of the terpyridine is changed from tridentate in the binary complex to bidentate in the ternary one where the uncoordinated pyridine exists in the protonated form. The dto and tsc act as neutral bidentate ligands coordinating through either sulfur or sulfur and nitrogen atoms respectively, forming chelate ring systems

The ‘complexes as metal’ strategy has been used to prepare new mixed ligand complexes containing Co(II), Ni(II) and Cu(II) terpyridine (terpy) with dithiooxamide (dto) and thiosemicarbazide (tsc). Characterization of the complexes has been accomplished by elemental analysis, molar conductance, thermal analysis, as well as electronic and IR spectral measurements. It is deduced that the coordination mode of the terpyridine is changed from tridentate in the binary complex to bidentate in the ternary one where the uncoordinated pyridine exists in the protonated form. The dto and tsc act as neutral bidentate ligands coordinating through either sulfur or sulfur and nitrogen atoms respectively, forming chelate ring systems

The ‘complexes as metal’ strategy has been used to prepare new mixed ligand complexes containing Co(II), Ni(II) and Cu(II) terpyridine (terpy) with dithiooxamide (dto) and thiosemicarbazide (tsc). Characterization of the complexes has been accomplished by elemental analysis, molar conductance, thermal analysis, as well as electronic and IR spectral measurements. It is deduced that the coordination mode of the terpyridine is changed from tridentate in the binary complex to bidentate in the ternary one where the uncoordinated pyridine exists in the protonated form. The dto and tsc act as neutral bidentate ligands coordinating through either sulfur or sulfur and nitrogen atoms respectively, forming chelate ring systems

A series of novel dinuclear mixed-ligand complexes having the general formula [M2(tpt)(L)4]Cl4.nH2O where M = Ni(II), Co(II) or Cu(II); tpt = 2,4,6-tris(2-pyridyl)-1,3,5-triazine; L = dithiooxamide (dto) or thiosemicarbazide (tsc); n = 2 - 4, have been synthesized and characterized. The tpt molecule is flexidentate, where it can behave as di- or tridentate and either mono- or dinucleating ligand. The coordination mode of the tpt to the M(II) apparently occurs through pyridyl and a triazine nitrogen atoms. The binary complexes have the formulas [Co2(tpt)Cl4H2O].2H2O, [Ni(tpt)Cl]Cl.5.5H2O and [Cu(tpt)Cl2].3H2O. All the mixed-ligand complexes are dinuclear with bridging tpt molecule and having an octahedral structure. Binary Co(II) and Cu(II) complexes are probably penta coordinated. The complexes under study were characterized by chemical analysis, spectral, molar conductance and thermal studies

A series of novel dinuclear mixed-ligand complexes having the general formula [M2(tpt)(L)4]Cl4.nH2O where M = Ni(II), Co(II) or Cu(II); tpt = 2,4,6-tris(2-pyridyl)-1,3,5-triazine; L = dithiooxamide (dto) or thiosemicarbazide (tsc); n = 2 - 4, have been synthesized and characterized. The tpt molecule is flexidentate, where it can behave as di- or tridentate and either mono- or dinucleating ligand. The coordination mode of the tpt to the M(II) apparently occurs through pyridyl and a triazine nitrogen atoms. The binary complexes have the formulas [Co2(tpt)Cl4H2O].2H2O, [Ni(tpt)Cl]Cl.5.5H2O and [Cu(tpt)Cl2].3H2O. All the mixed-ligand complexes are dinuclear with bridging tpt molecule and having an octahedral structure. Binary Co(II) and Cu(II) complexes are probably penta coordinated. The complexes under study were characterized by chemical analysis, spectral, molar conductance and thermal studies

Ni[CH3(CH2)17PO3]·H2O was prepared and characterized by several techniques and the magnetic properties were measured by using a SQUID magnetometer. Preliminary refinement of the X-ray diffraction powder data by structure-less Le Bail fitting could be obtained and the compound was found to crystallise in the orthorhombic space group Pmn21 with a=5.478(7) Å, b=42.31(4) Å, c=4.725(3) Å. Ni(II)octadecyl phosphonate is lamellar and the structure consists of alternating inorganic and organic layers. The inorganic layers are interspersed by by-layers of the octadecyl substituent and van der Waals contacts are established between them. IR spectroscopy revealed all-trans configuration of the hydrocarbonic chain. A tilt angle of 48.2° between the chain axis and the (ac) plane could be estimated. The temperature dependence of the molar susceptibility plotted as 1/χ vs. T is linear above 100 K and it follows the Curie–Weiss law. The Curie, C, constant suggests the presence of Ni(II) ion in the S=1 spin state and the negative Weiss, θ, constant is indicative of antiferromagnetic nearest neighbour exchange interactions. Zero-field and field-cooled χ vs. T plots were then recorded. The plots show no overlap below 20 K, thus indicating that the compound is in an ordered magnetic state. The critical temperature has been located at the onset of the χ vs. T plot and was found to be TN=21 K. The magnetization vs. field plots, measured at different temperatures, provide the indication that the compound is a weak-ferromagnet below TN.

Ni[CH3(CH2)17PO3]·H2O was prepared and characterized by several techniques and the magnetic properties were measured by using a SQUID magnetometer. Preliminary refinement of the X-ray diffraction powder data by structure-less Le Bail fitting could be obtained and the compound was found to crystallise in the orthorhombic space group Pmn21 with a=5.478(7) Å, b=42.31(4) Å, c=4.725(3) Å. Ni(II)octadecyl phosphonate is lamellar and the structure consists of alternating inorganic and organic layers. The inorganic layers are interspersed by by-layers of the octadecyl substituent and van der Waals contacts are established between them. IR spectroscopy revealed all-trans configuration of the hydrocarbonic chain. A tilt angle of 48.2° between the chain axis and the (ac) plane could be estimated. The temperature dependence of the molar susceptibility plotted as 1/χ vs. T is linear above 100 K and it follows the Curie–Weiss law. The Curie, C, constant suggests the presence of Ni(II) ion in the S=1 spin state and the negative Weiss, θ, constant is indicative of antiferromagnetic nearest neighbour exchange interactions. Zero-field and field-cooled χ vs. T plots were then recorded. The plots show no overlap below 20 K, thus indicating that the compound is in an ordered magnetic state. The critical temperature has been located at the onset of the χ vs. T plot and was found to be TN=21 K. The magnetization vs. field plots, measured at different temperatures, provide the indication that the compound is a weak-ferromagnet below TN.