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The isomeric distribution and rearrangement of complexes of the type [CoX[L.sub.n].super. 2

The reaction of Ln([N[O.sub.3]).sub.3) with [K.sub.3][Cr[CN.su.6)] and 2,2-bipyridine (bpy) in a water/ethanol solution is found to lead to two families of complexes. The magnetic results obtained in the full lanthanide series using {[Fe[CN.sub.6]}.sup.3-] and bpy as the blocking ligand are presented.

The synthesis and structural characterization of polynuclear copper (II) complexes derived from 1,3-bis (dimethylamino)-2-propanolato is described. The magnetic behavior of these complexes has been investigated, showing strong antiferromagnetic coupling in all the cases.

Results show that trinuclear copper(sup)II(sub)3 cation systems exhibit one- dimensional systems using XCN(sup)- as a bridging ligand and with X = S or Se. Data reveal that the homotrinuclear complexes are similar in structures possessing a trinuclear copper(II) complexes.

The synthesis, crystal structure, magnetic properties, and Mossbauer spectra of [Fe(bpb)2(NCS)2]. 0.5CH3OH are reported. It is a singular example of the interpenetration of three mutually perpendicular nets with spin crossover properties.

Two new one-dimensional nickel(II) complexes were synthesized and characterized. The two complexes are similar and may be described as one-dimensional with double-azido-bridged ligands in end-to-end and end-on coordination alternatively, while the end-on moiety is almost identical for the two complexes, the end-to-end moiety is different in each structure.

A study is conducted on new iron(III)-SB complexes with the general formula (Fe(L)(HIm)2). These complexes are obtained from the reaction of Fe(L1)Cl.H2O (L1 = N,N'-3,4-toluenebis(3-ethoxysalicylideneimine)), Fe(L2)Cl.H2O (L2 = N,N'-4-chloro-omicron-phenylenebis(3-methoxysalicylideneimine)), Fe(L3)Cl.H2O (L3 = N,N'-4-chloro-omicron-phenylenebis(3-methoxysalicylideneimine)) and Fe(L4)Cl.H2O (L4 = N,N'-1,2-propylenebis(3-methoxysalicylideneimine)) with imidazole in methanol.

The synthesis and magnetic properties of four new (Cu-Ni)2 tetranuclear complexes of general formula (Cu(oxpn)Ni(mu-NCS)(H2O)(aa))2(X)2 (oxpn = N, N'-bis(3-aminopropyl)oxamide; aa = bidentate amine; X = CIO4- or PF6-) are presented. The antiferromagnetic coupling was given by the oxpn ligand while the ferromagnetic coupling was given by the thiocyanate anion. Using X-ray crystallography, the structures of three of these complexes were proven to be tetranuclear. Results indicate that in the new tetranuclear complexes, the antiferromagnetic coupling through the oxamidato bridge is dominant.

X-ray diffraction methods were used to characterize the structure of a newly developed spin crossover dihydrobis(1-pyrazolyl)borate {H2B(pz)2}-containing iron(II) complexes. It was shown that a decrease in temperature as well as trigonal deformation angle modification resulted in structural modification relative to the spin change of the Fe-N angles. Furthermore, the positive charge of iron(II) was neutralized through the chelate anions.

A one-dimensional compound, (Mn(bipy)(N3)2) (bipy = 2,2'bipyridine) was synthesized and characterized structurally and in terms of its spectroscopic and magnetic properties. The results showed that the compound bears Mn(II) ions alternatively bridged by two end-on and two end-to-end azido ligands, a conformational property that is responsible for the observed ability of the compound to undergo alternating ferro- and antiferromagnetic interactions.

The preparation and characterization of (Ni(1,3-diamino-2,2-dimethylpropane)2(mu-N3))n(PF6)n and (Ni(1,3-diaminopropane)2(mu-N3))n(PF6)n are discussed. The two nickel(II) trans-monodimensional, antiferromagnetically-coupled azide-bridged complexes, both of which crystallize in the orthorhombic space group Pnmn, exhibit similar structures at room temperature but become unstable at low temperatures due to a change in the magnetic susceptibility caused by phase transition.

A trinuclear nickel(II) complex with strong antiferromagnetic coupling, (mu(sub 3)-CO3)(Ni3(Medpt)3(NCS)4), exhibits a new asymmetric coordination mode of three nickel atoms bonded by a single pentadentate carbonato ligand. Reaction of thiocyanate ligand and (bis(3-aminopropyl)methylamine) solution in the presence of CO2 produces the complex. Magnetic behavior of the carbonato bridge is discussed.

The novel (mu-oxo)bis(mu-carboxylato)dimanganese(III) complex Mn2O(PhCOO)2(bpy)2(OH)(NO3) .H2O is separated and structurally characterized by X-ray crystallography. The structure of the complex shows triply-bridged (Mn2 mu-O mu-PhCOO 2)2+ dinuclear core with the Mn(III) ions each having chelating bpy and terminal OH- or NO3- anions thereby generating a twisted octahedral configuration. The magnetic properties of the complex show axial zero-field splitting of the Mn(III) at mild temperatures, which are greatly influenced by Jahn-Teller distortions.

The synthesis and characterization of the copper(II) trinuclear micro3-CO(sub3)(super 2-) system (micro-CO3)Cu3(Medpt)3(ClO4)3(ClO4) is described. Structural analysis showed the quasi-equilateral triangular arrangement of copper atom and micro3 coordination of the carbonato bridge. Molecular orbital analysis was used to explain the magnetic trends for the anti-anti-anti coordination mode for the carbonato.

Two nickel(II) polynuclear end-to-end azide bridge compounds, (NiL2{mu-N3})n(ClO4)n (1) and (NiL{mu-N3})n(PF6)n (2), where L = 1,2-diamino-2-methylpropane, was synthesized and characterized. Both their structures are similar but their magnetic behaviors are different. This is due to the greater compactness formed by the perchlorate anion and the difference magnetic pathways. In this, d(sub xy)-d(sub xy) exhibits the antiferromagnetism in 1 while the mixing of d(sub xy)-d(sub xy) + d(sub xy)-d(sub z)2 diminishes the antiferromagnetism in 2.

X-ray crystallography helps determine the structure of an uniform monobridged mu-azido chain ((Ni(Me2(14)-1,3-dieneN4)(mu-N3))n)(ClO4)n, where Me2(14)-1,3-dieneN4 is the macrocycle 2,3-dimethyl-1,4,8,11-tetraazacyclotetradeca-1,3-diene. Magnetic susceptibility study helps analyze the magnetic behavior of the chain. Molecular orbital extended Huckel calculations help correlate the bond parameters with magnetic susceptibility data.

The synthesis and characterization of two new nickel(II) end-to-end azido-bridged compounds, cis-catena(NiL2 mu-N3 )n(ClO4)n.nH20 and (Ni2L4 muN3 sub 2)(PF6), are presented. Analysis showed that the first compound is a one-dimensional helicoidal complex with the two L ligands and the two end-to-end azido bridges in a cis arrangement while the second compound is a dinuclear system with two end-to-end azido bridges. Both compounds exhibited antiferromagnetic coupling behavior.

X-ray crystallographic studies of an alternating magnetic chain system with local spin S=1, with the formula ((Ni2(dpt)2(mu-ox)(mu-N3))n)(PF6)n (dpt = bis-(3-aminopropyl)amine) reveal that in the system one oxalato and one azido bridges alternatively join the Ni(dpt)2+ units. Magnetic susceptibility studies between 4 and 300 K reveal the antiferromagnetic coupling of the system.

Single-crystal x-ray diffraction studies help determine the crystal structures of two new synthetic dinuclear complexes having thiocyanato bridging ligands. In both complexes, NCS- bridges two Ni(II) atoms. While one complex has two dinuclear entities the other has only one dinuclear entity. Magnetic susceptibility studies help examine the ferromagnetic properties of these complexes and analyze the magneto-structural trends in these molecules.

Two compounds cis(Ni(333-tet)(mu-N3))n(ClO4)4 and trans-(Ni(333-tet)(mu-N3))(n)(ClO4)(n)(333-tet-tetramine N,N'-bis(3-amino propyl)-1,3-propanediamine) are synthesized. Structural studies in these compounds show the presence of two monobridged nickel(II)-azido systems. Magnetic and structural parameters of this azido ligand are correlated by a model.

Blue crystals of the infinite bidimensional antiferromagnetic polymer (Ni(N3)2(2,2-dimethylpropane-1,3-diamine))(n) are obtained by the reaction of aqueous solution of Ni(Cl04)2 and NaN3 with 2,2-dimethylpropane-1,3-diamine. The reaction also yields a new coordination mode. The polymer crystallizes when placed in a monoclinic system. Nitrogen atoms in the monoclinic ligand coordinate the Ni(II) atoms octahedrally.

Four synthesized ferromagnetic Ni(II) polynuclear complexes containing an end-on azido fragment as a bridging ligand form the first examples of one dimensional Ni(II)-azido ferromagnetic system. Two complexes crystallize in a monoclinic system whereas one crystallizes in a triclnic system. Measurement of susceptibility against temperature reveals that two of the four complexes are metamagnetic at lower temperature ranges.

The X-ray analysis is used to study the composition of five new trinuclear Cu(II) complexes. The crystals of the complexes are found to be orthorhombic, triclinic and monoclinic. Coplanar basal planes with square-planar copper(II) ions are seen in ((N,N,N', N'-tetramethylethylenediamine)Cu2)2 (mu-Cu(pba))(ClO4)2 where Cu(pba) is 1, 3-propanediylbis(oxamato)cuprate(II). A perchlorate and a water oxygen are found in the apical places of (((pet)Cu)2 (mu-Cu(pba))) (ClO4)2.1/2H2O and (((bapa)Cu)2(mu-Cu(pba)(H2O)))-(PF6)2 respectively, where pet is N,N,N',N'', N''-pentaethyldiethylenetriamine and bap is bis(3-aminopropyl)amine, and where the central copper(II) ions are square-pyramidal. The square-planar central copper ion is found in (((pmd)Cu)2 (micro-Cu(pba))) where pmd is N,N,N',N'', N''-pentamethyldiethylenetriamine.

Two differing catena formulas have been used to prepare and examine two novel monodimensional (mu-azido) nickel(II) complexes. The monoclinic crystalline structure of (C7H20N7Ni)n(ClO4)n and the orthorhombic crystalline structure of (C8H22N7Ni)n(ClO4)n reveal varying space group values. The mu-azido groups are in trans positions in both complexes, and the nickel atoms are positioned in an octahedral surrounding. The heat changes the molar susceptibility, revealing the magnetic characteristics of the complexes which are similar to those of an antiferromagnetically coupled nickel(II) standard chain. A sequence of analogous processes reveals the magneto-structural correlations.

A new dinuclear species consisting of 2 N3- bridges is synthesized by employing several bidentate amines as blocking ligands for each Ni(II) ion. This is aimed at extending the magneto-structural correlations in dinuclear or Co(II) complexes, characterized by azido bridges, to Ni (II) compounds. The magnetic properties of the three new Ni(II) dinuclear azide-bridged compounds are analyzed by determining the susceptibility function of temperature. An antiferromagnetic behaviour results from 1, 3-coordination of Ni(II) ions while 1,3-coordination gives rise to ferromagnetic coupling.

The synthesis, crystal structure and magnetic behavior of dinuclear Ni(II) complexes (micro-N3)2(Ni(Me3(12)N3))2(ClO4)2.2H2O, (micro-N3)2(Ni(Me4(12)N3))2(ClO4)2.H2O and (micro-N3)2(Ni(232-N4))2(ClO4)2 were reported. Me3(12)N3 is 2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene, Me4(12)N3 is its 9-methyl derivative and 232-N4 is N,N'-bis(2-aminoethyl)-1, 3-propanediamine. Magnetic interactions in these compounds are discussed in terms of bonding differences.

The first ferromagnetic tetranuclear Ni(II) complex (Ni4(mu-N3)4(2-oxo- 1,3-diaminopropane)2(2-hydroxo-1, 3-diaminopropane)2)(ClO4)2 was synthesized and characterized by X-ray crystallography, elemental analyses, IR and EPR spectra. The complex with the formulation C12H38N20Ni4O4(ClO4)2 consisted of 1,1-azido and one OH bridge and exhibit ferromagnetic properties as an effect of spin polarization.

Seven heterodinuclear Cu(super II)Ni(super II) complexes with an octahedral or pentacoordinated Ni(II) environment were synthesized and characterized. These complexes were prepared from the reaction of the corresponding mononuclear Cu(II) complex with (Ni cth)(ClO4)2. The unit cells of both (Ni cth Cu oxpn)(ClO4)2 and (Ni Me3 12 N3 Cu Me2oxpn)(ClO4)2 consist of four dinuclear (NiCu) dications and two symmetrically independent sets of four perchlorate anions. A 2.5% distortion of the N4 environment of the copper atom of the former compound exists.

The acetic acid adduct of Rh2(O2CCH3)3 (C6H4)P(o-ClC6H4)(C6H5) serves as a model Rh4(II) complex with a single ortho-metalated phosphine bridging two Rh atoms. The acetic acid can be displaced in solution by P(p-XC6H4)3. On heat treatment, a bimetallated compound with an additional (XC6H3)P(XC6H4) forms. The use of excess P(p-XC6H4) speeds up dimerization and allows total CH3COOH substitution. The character of X determines the reaction rate, increasing in the order of X = Cl to H to CH3. Both head-to-head and head-to-tail bridgings occur. Two reaction routes are proposed to account for these differences.

The crystal structure and DNA interaction of the tris-chelate Co(III) complex fac-[Co[(ambi).sub.3]][Cl.sub.3]*3[H.sub.2]O which could be exploited to counteract DNA condensation uniquely arising from electrostatic force in the presence of multivalent [[Co[(ambi).sub.3]].sup.3+] is reported. Results reveal that the metal q/r ratio and ring functionality could be exploited to modulate the binding affinities of multivalent complexes, thereby offering potential applications in chemotherapy against cancer and careful control of the DNA condensation reaction in gene therapy.

A tridentate amine ligand, bis(3-amino propyl)-amine, is used to synthesize the nickel(II) alternating chain complex catena-(Ni2(mu-N3)3(dpt2)2)(ClO4). Magnetic susceptibility measurements confirm the theory that this is the first N(II) chain to alternate magnetically. X-ray crystallography analysis is done using crystals grown from a synthetic pathway.

The synthesis of a family of new Ru complexes containing meridional or facial tridentate ligands with general formula is described. All complexes are spectroscopically characterized in solution through [sup.1.H] NMR and UV-vis techniques.

The synthesis, crystallographic analysis, and magnetic properties of six cyclobutanedicarboxylate copper (II) complexes, starting from the simple copper(II) salt, without any other ligand, and following with five different derivatives by adding specific ligands are reported. Results demonstrate that, in most cases, it is difficult to predict the exact structures and composition of the assembly products formed by mixed ligands when subtle variations are introduced into the main skeleton of the ligand.

A report is presented on how the subtle variations exemplified in the family of dinucleating hexaaza macrocyclic ligands strongly influence the reactivity of their corresponding Cu(super 1)2 complexes toward molecular O2 and their oxidative evolution. DFT calculations have provided an excellent guide to unravel their potential reactivity based on the relative disposition of the aromatic rings and the Cu2O2 core and also on their electronic properties.

It is emphasized that the molecular recognition of dicarboxylic acids is achieved through the formation of anionic complexes with hexaazamacrocyclic ligands. The fundamental features involved in host-guest binding interactions with different dicarboxylic acids, including the geometrical fit are described.

Tridentate/tetradentate Schiff base ligands react with nickel acetate or perchlorate salt and azide, cyanate, or thiocyanate to give rise to a series of four dinuclear complexes. The magnetic and spectroscopic study of the series is reported.

The study stated that the combined use of dca and bipym has led to the preparation of three extended frameworks with Mn(II) and Cu(II), which are synthesized under similar conditions, where the bipym ligand was added on the metal in 1/2 proportion. The weak antiferromagnetic interactions are in agreement with the existence of double discyanamide bridges, while strong and moderate antiferromagnetic interactions are associated to the bipyrimidine bridges.

Synthesis and structural analysis of a bis(mu-thiocyanato) nickel (II) dinuclear compound, (mu-SeCN)2(Ni(Medpt)SeCN)2, where Medpt = N,N-bis(3-aminopropyl)methylamine, reveal the presence of discrete Ni(Medpt)(SeCN)2 entities. Hydrogen bonds are absent between dinuclear entities. This dinuclear compound is ferromagnetically coupled.