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Two new 1D chains [(CuL 1R ) 2 Cu 2 (N 3 ) 2 ( μ 1,1,3 -N 3 ) 2 ] n ( 1 ) and [{(CuL 2R ) 2 Cu 2 (N 3 ) 2 ( μ 1,1,3 -N 3 ) 2 }·(CH 3 ) 2 CO] n ( 2 ) based on rare μ 1,1,3 -N 3 bridged tetranuclear Cu(II) complexes, have been synthesized using [CuL 1R ] and [CuL 2R ] as “metalloligands” [where H 2 L 1R  = N,N′-bis(2-hydroxybenzyl)-1,3-propanediamine and H 2 L 2R  = N,N′-bis(2-hydroxybenzyl)-1,2-ethylenediamine]. Both complexes have been characterized by elemental analysis, spectroscopic methods, single crystal XRD, and magnetic study. In case of chain 1 , the basic building block is a centrosymmetric tetranuclear unit whereas for 2 , it is an asymmetric tetranuclear unit containing two types of square pyramidal Cu(II) centers (terminal and central). The μ 1,1 -N 3 bridged central copper atoms of one tetranuclear unit are connected weakly to the axial position of the terminal copper atoms of neibouring units via the azide ions forming a rare μ 1,1,3 -N 3 bridged novel 1D polymeric chain structure. Variable temperature magnetic susceptibility measurements show the presence of an overall strong antiferromagnetic exchange interactions mediated through the double phenoxido bridges with J values of −123.8 and −144.6 cm −1 for 1 and 2 , respectively. [ABSTRACT FROM AUTHOR]

Abstract: Three new Ni(II) complexes, [NiL(NO2)(H2O)] (1), [Ni2L2(PhCH2COO)2(H2O)] (2) and [Ni2L2(N(CN)2)2(H2O)] (3), have been synthesized using a tridentate Schiff base ligand, 1-[(3-dimethylamino-propylimino)-methyl]-naphthalen-2-ol (HL) and the polyatomic monoanions NO2 −, PhCH2COO− or N(CN)2 −. All three complexes (1–3) have been characterized by spectral analysis and X-ray crystallography. Structural analyses reveal that complex 1 is mononuclear, in which the Ni(II) ion is in a distorted octahedral environment, coordinated by the deprotonated tridentate Schiff base (L), a chelating nitrite and one water molecule. The structures of both 2 and 3 consist of dinuclear octahedral Ni(II) units with crystallographic C2 symmetry. In complex 2, two μ2-phenoxido and a water molecule bridge the two Ni(II) centers to make the complex a face sharing bioctahedron, whereas in 3 the Ni(II) atoms are bridged by two μ1,5-dicyanamide ligands. Variable temperature magnetic susceptibility measurements show the presence of ferromagnetic coupling in complex 2 with J =+26.20cm−1 and antiferromagnetic coupling in complex 3 with J =−1.90cm−1. [Copyright &y& Elsevier]

Abstract: Two triangular tri-nuclear, hetero-metallic copper(II)-nickel(II) complexes, [(CuL)2Ni{N(CN)2}2]·H2O (1) and [(CuL)2Ni(NCS)2]·H2O (2) have been synthesized by reacting “ligand complex” [CuL] with Ni(ClO4)2 in presence of polyatomic anions, dicyanamide (dca) or thiocyanate in methanol–water medium, where H2L is a N2O2 donor di-Schiff base derived from 1,3-propanediamine and 2-hydroxyacetophenone. Both the complexes have been structurally and magnetically characterized. In both complexes, two [CuL] units coordinate to a nickel atom through the coordination of the phenoxido oxygen atoms forming triple phenoxido bridges between each Cu(II) and Ni(II). A couple of terminal dca or N-bonded thiocyanate ions complete the distorted octahedral geometry around Ni(II) in 1 and 2 respectively. Variable temperature magnetic susceptibility measurements show the presence of moderate antiferromagnetic exchange interactions mediated through the phenoxido bridges with J values (H = −J∑SiSi +1) of −49 and −42cm−1 for 1 and 2 respectively. [Copyright &y& Elsevier]

The reaction of Ln(NO[sub 3])[sub 3]·aq with K[sub 3][Fe(CN)[sub 6]] or K[sub 3][Co(CN[sub )]6] and 2,2'-bipyridine in water led to five one-dimensional complexes: trans-[M(CN)[sub 4](µ-CN)[sub 2]Ln(H[sub 2]O)[sub 4] (bpy)][sub n]·XnH[sub 2]O·1.5nbpy (M = Fe[sup 3+] or Co[sup 3+]; Ln = Sm[sup 3+], Gd[sup 3+], or Yb[sup 3+]; X = 4 or 5). The structures for [Fe[sup 3+]-Sm[sup 3+]] (1), [Fe[sup 3+]-Gd[sup 3+]] (2), [Fe[sup 3+]-Yb[sup 3+]] (3), [Co[sup 3+]-Gd[sup 3+]] (4), and [Co[sup 3+]-Yb[sup 3+]] (5) have been solved; they crystallize in the triclinic space P&1macr; and are isomorphous. The [Fe[sup 3+]-Sm[sup 3+]] complex is a ferrimagnet, its magnetic studies suggesting the onset of weak ferromagnetic 3-D ordering at 3.5 K. The [Fe[sup 3+]Gd[sup 3+]] interaction is weakly antiferromagnetic. The isotropic nature of Gd[sup 3+] allowed us to evaluate the exchange interaction (J = 0.77 cm[sup -1]). [ABSTRACT FROM AUTHOR]

A diphenoxido-bridged dinuclear copper(ll) complex, [Cu2L2(ClO4)2 (1), has been synthesized using a tridentate reduced Schiff base ligand, 2-[[2-(diethylamino)-ethylamino]methyl]phenol (HL). The addition of triethyl-amine to the methanolic solution of this complex produced a novel triple bridged (double phenoxido and single hydroxido) dinuclear copper(ll) complex, [Cu2L2(OH)]ClO4 (2). Both complexes 1 and 2 were characterized by X-ray structural analyses, variable-temperature magnetic susceptibility measurements, and spectroscopic methods. In 1, the two phenoxido bridges are equatorial--equatorial and the species shows strong antiferromagnetic coupling with J = --6lS.6(6.l) cm-1. The inclusion of the equatorial--equatorial hydroxido bridge in 2 changes the CuṪCu distance from 3.018 Å (avg.) to 2.798 Å (avg.), the positions of the phenoxido bridges to axial--equatorial, and the magnetic coupling to ferromagnetic with J = 50.1(1.4) cm-1. Using 3,5-di-terf-butylcatechol as the substrate, the catecholase activity of the complexes has been studied in a methanol solution; compound 2 shows higher catecholase activity (kcat = 233.4 h-1) than compound 1 (kcat = 93.6 h-1). Both complexes generate identical species in solution, and they are interconvertible simply by changing the pH of their solutions. The higher catecholase activity of 2 seems to be due to the presence of the OH group, which increases the pH of its solution. [ABSTRACT FROM AUTHOR]

Abstract: The 1:1 condensation of N-methyl-1,3-diaminopropane and N,N-diethyl-1,2-diminoethane with 2-acetylpyridine, respectively at high dilution gives the tridentate mono-condensed Schiff bases N-methyl-N′-(1-pyridin-2-yl-ethylidene)-propane-1,3-diamine (L1) and N,N-diethyl-N′-(1-pyridin-2-yl-ethylidene)-ethane-1,2-diamine (L2). The tridentate ligands were allowed to react with methanol solutions of nickel(II) thiocyanate to prepare the complexes [Ni(L1)(SCN)2(OH2) (1) and [{Ni(L2)(SCN)}2] (2). Single crystal X-ray diffraction was used to confirm the structures of the complexes. The nickel(II) in complex 1 is bonded to three nitrogen donor atoms of the ligand L1 in a mer orientation, together with two thiocyanates bonded through nitrogen and a water molecule, and it is the first Schiff base complex of nickel(II) containing both thiocyanate and coordinated water. The coordinated water initiates a hydrogen bonded 2D network. In complex 2, the nickel ion occupies a slightly distorted octahedral coordination sphere, being bonded to three nitrogen atoms from the ligand L2, also in a mer orientation, and two thiocyanate anions through nitrogen. In contrast to 1, the sixth coordination site is occupied by a sulfur atom from a thiocyanate anion in an adjacent molecule, thus creating a centrosymmetric dimer. A variable temperature magnetic study of complex 2 indicates the simultaneous presence of zero-field splitting, weak intramolecular ferromagnetic coupling and intermolecular antiferromagnetic interactions between the nickel(II) centers. [Copyright &y& Elsevier]

Abstract: A new linear trinuclear nickel(II) complex, [Ni3(salme)2(OCn)4] (Hsalme=2-[(3-methylamino-propylimino)-methyl]-phenol, OCn=cinnamate), showing weak ferromagnetic coupling (J =1.8(1)cm−1) through phenoxo and a novel tridentate bridging mode (1κ2 OO′:2κO′) of the cinnamate ligand has been synthesized and structurally characterized by X-ray crystallography. [Copyright &y& Elsevier]

The reaction of Ln(NO3)3(aq) with K3[Fe(CN)6] or K3[Co(CN)6] and 2,2′-bipyridine in water/ethanol led to 13 one-dimensional complexes: trans-[M(CN)4(µ-CN)2Ln(H2O)4(bpy)]n·4nH2O·1.5nbpy (Ln = Eu3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Lu3+; M = Fe3+, Co3+). The structures for [EuFe]n (1), [TbFe], (2), [DyFe]n (3), [HoFe]n (4), [ErFe]n (5), [TmFe]n (6), [LuFe]n (7), [EuCo]n (8), [TbCo]n (9), [DyCo]n (10), [HoCo]n (11), [ErCo]n (12), and [TmCo]n (13) have been solved: they crystallize in the triclinic space group P1 and are isomorphous. They exhibit a supramolecular architecture created by the interplay of coordinative, hydrogen bonding, and π-π interactions. A stereochemical study of the eight-vertex polyhedra of the lanthanide ions, based on continuous shape measures, is presented. The Ln3+-Fe3+ interaction is antiferromagnetic in [DyFe]n and [TbFe]n. For [EuFe]n, [HoFe]n, [ErFe]n, and [TmFe]n, there is no sign of any significant interaction. The magnetic behavior of [DyFe]n suggests the onset of weak long-range ferromagnetic ordering at 2.5 K. [ABSTRACT FROM AUTHOR]

The reaction of Ln(NO3)3(aq) with K3[Fe(CN)6] or K3[Co(CN)6] and 2,2′-bipyridine in water/ethanol led to eight trinuclear complexes: trans-[M(CN)4(µ-CN)2{Ln(H2O)4(bpy)2}2][M(CN)6]·8H2O (M = Fe3+ or Co3+, Ln = La3+, Ce3+, Pr3+, Nd3+, and Sm3+). The structures for the eight complexes [La2Fe] (1), [Ce2Fe] (2), [Pr2Fe] (3), [Nd2Fe] (4), [Ce2Co] (5), [Pr2Co] (6), [Nd2Co] (7), and [Sm2Co] (8) have been solved; they crystallize in the triclinic space group P1 and are isomorphous. They exhibit a supramolecular 3D architecture through hydrogen bonding and π-π stacking interactions. A stereochemical study of the nine-vertex polyhedra of the lanthanide ions, based on continuous shape measures, is presented. No significant magnetic interaction was found between the lanthanide(III) and the iron(III) ions. [ABSTRACT FROM AUTHOR]