María I. Arriortua

(C2H10N2)[Cr(HPO3)F3]: The First Organically Templated Fluorochromium(III) Phosphite†

� 3 gL � 1 ) with C32H66 ,C 44H90 ,C 50H102 (1.3 i 10 � 2 gL � 1 ) were spin-coated onto the basal plane of highly oriented pyrolytic graphite (HOPG, Advanced Ceramics Co., USA, quality ZYH at 40 rps). The coated graphite samples were dried for 10 min at 408C before SFM investigations were carried out with a Nanoscope IIIa (Digital Instruments, Santa Barbara, CA) in the tapping mode. An E-scanner over a range of scan lengths from 5 to 0.3 mm, and commercial Si cantilevers (length 125 mm and width 30 mm) with spring constants between 17 and 64 N m � 1

Synthesis and spectroscopic properties of copper(II) complexes derived from thiophene-2-carbaldehyde thiosemicarbazone. Structure and biological activity of [Cu(C6H6N3S2)2].

The synthesis, structure and spectroscopic properties on complexes with the formula [Cu(Lm)2] (1) and Cu(NO3)2(HLm)2 (2), where HLm = thiophene-2-carbaldehyde thiosemicarbazone, have been developed. The molecular structure of compound 1 consists of monomeric entities. The copper(II) ions exhibit distorted square-planar geometry with both bidentate thiosemicarbazone ligands placed in a centrosymmetric way. Metal to ligand pi-backdonation is proposed to explain several structural and spectroscopic features in these complexes. The EPR spectra of compound 1 show an orthorhombic g tensor indicating the presence of weak magnetic exchange interactions. The reaction of compound 1 with glutathione causes the reduction of the metal ion and the substitution of the thiosemicarbazone ligand by the thiol ligand. This mechanism seems to be related to the cytotoxicity of this complex against Friend Erithroleukemia cells (FLC) and melanome B16F10 cells.

Spectroscopic and magnetic properties of copper(II) complexes derived from pyridine-2-carbaldehyde thiosemicarbazone. Structures of [Cu(NO3)(C7H8N4S)(H2O)](NO3) and [{Cu(NCS)(C7H7N4S)}2]

Abstract Complexes with the formula CuX(L) (X=N3 1, NCO 2 and NCS 3) and [Cu(NO3)(HL)(H2O)](NO3) 4, where HL=C7H8N4S, (pyridine-2-carbaldehyde thiosemicarbazone), have been characterised. Single-crystal X-ray diffraction studies on compounds 3 and 4 have been carried out. The structure of compound 4 consists of monomeric distorted square pyramidal copper(II) species. The copper(II) ions are coordinated to the NNS atoms from the tridentate thiosemicarbazone ligand and one oxygen atom of a nitrate group in the equatorial position. The oxygen atom of the water molecule occupies the apical position. The structure of compound 3 consists of non-centrosymmetric {Cu2(μ-SR)2} entities in which the copper(II) ions exhibit five-coordinate square–pyramidal geometry. The thiosemicarbazone ligand and one nitrogen atom from the thiocyanate ion are in a basal position. The sulfur atom of the tridentate ligand acts as a bridge occupying the apical position. Structural and spectroscopic results suggest the presence of relevant σ ligand-to-metal charge transfer and metal-to-ligand π-backdonation character in these compounds. The ESR spectra of compounds 3 and 4 show rhombic symmetry. For complexes 1 and 2 the ESR spectra exhibit axial signals. Magnetic measurements on compounds 1, 2 and 3 show antiferromagnetic couplings. The susceptibility data were fitted by the Bleaney–Bowers’ equation for copper(II) dimers. The obtained J/k values are −4.22, −6.10 and −7.33 K for compounds 1, 2 and 3, respectively.

Biological activity of complexes derived from pyridine-2-carbaldehyde thiosemicarbazone: Structure of [Co(C7H7N4S)2][NCS]

Biological studies on [Fe(L)2](NO3).0.5H2O (1), [Fe(L)2][PF6] (2), [Co(L)2](NCS) (3), [Ni(HL)2]Cl2.3H2O (4) and Cu(L)(NO3) (5), where HL=C7H8N4S, pyridine-2-carbaldehyde thiosemicarbazone, have been carried out. The crystal structure of compound 3 has been solved. It consists of discrete monomeric cationic entities containing cobalt(III) ions in a distorted octahedral environment. The metal ion is bonded to one sulfur and two nitrogen atoms of each thiosemicarbazone molecule. The thiocyanate molecules act as counterions. The copper(II) and iron(III) complexes react with reduced glutathione and 2-mercaptoethanol. The reaction of compound 1 with the above thiols causes the reduction of the metal ion and bis(thiosemicarbazonato)iron(II) species are obtained. The redox activity, and in particular the reaction with cell thiols, seems to be related to the cytotoxicity of these complexes against Friend erithroleukemia cells and melanoma B16F10 cells.

Organically templated open-framework phosphites

Here we present a summary of the work carried out in the last few years on the synthesis and characterization of a new type of organically templated inorganic–organic solid based on the (HPO3)2−phosphite oxoanion, with special focus on the magnetostructural properties of those systems containing open d-shell transition metal ions. As a result of the inherent connectivity of the metal-phosphite framework, the magnetic behaviour of the great majority of these materials is characterized by weak antiferromagnetic interactions that become relevant only at low temperature.

Coordination behavior of cinoxacine: Synthesis and crystal structure of tris (cinoxacinate) cobaltate(II) of sodium hexahydrate (HCx = 1-ethyl-4(1H) -oxo-(1,3) dioxolo-(4,5g) cinnoline-3-carboxylic acid)

The synthesis, crystal, and molecular structure of Co(Cx)3Na6H2O are reported. The Cobalt(II) compound crystallizes in the trigonal system, space group R 3 with Z = 6, in a cell of dimensions a= 18.688(7) (A), c= 20.142(6) A. Least-squares refinement of 1331 reflections [I≥3σ(I)] gave a final R = 0.088 for all observed reflections. The structure consists of anionic monomeric units of (Co(Cx)3−) and sodium cations. Three Cinoxacinate ions are chelated through Oceto and Ocarbox atoms. The Co(II) ion positioned on the third axis is bonded to six oxygen atoms in a slightly distorted octahedral environment.

Structure and magnetic properties of the ferromagnetically coupled nickel dimer [Ni(terpy)(NCO)(H2O)]2(PF6)2

SummaryThe crystal structure of the dimeric [{Ni(C15H11N3)(NCO)(H2O)}2](PF6)2 has been determined by x-ray diffraction methods. Crystal data are as follows: P 1,a=11.904(4) Å,b=10.392(4) Å,c=8.531(3) Å, α=111.87(2)o, β=90.61(3)o, γ=107.37(5)o, U=926.7(4) Å3, Z=2, Dm=1.77(2), Dx=1.78 g. cm−3, μ(Mo-Kα)=12.1 cm−1, F(000)=494. Least-squares refinement of 1230 reflections with I≥1.5σ(1) gave a final R =0.035 (Rω=0.038). The structure is formed by cationic [{Ni(C15H11N3)(NCO)(H2O)}2]2+ and anionic PF6− units, linked through hydrogen bonds between the water molecule and the hexafluorophosphate ion. The resulting coordination geometry around each nickel(II) ion is ferragonally elongated octahedral. The N-bridging cyanate groups occupy simultaneously an equatorial position in the coordination sphere of one of the nickel atoms and an axial position in the other. The remaining axial positions are occupied by the water molecules. Powder susceptibility data, between 2.0 and 300 K, show the existence of ferromagnetic exchange between nickel centres. The magnetic parameters are J/K=6.6K, D/K =−17.6 K, z′J′/K=0.57 and g-2.21.

Structure and magnetic properties of two new polynuclear copper(II) complexes [Cu(terpy)(NCO)(H2O)](Y) (Y = NO3, PF6)

Abstract Compounds [Cu(terpy)(NCO)(H 2 O)](NO 3 ) ( I ) and [Cu(terpy)(NCO)(H 2 O)](PF 6 ) ( II ) (terpy = 2,2′:6′,2″-terpyridine) have been synthesized and the crystal structures have been determined. Complex I is monoclinic with space group P 2 1 / n and lattice parameters a = 9.698(2), b = 10.391(2), c = 16.681- (2) A, β = 95.54(4)°, U = 1673(1) A 3 and Z = 4. Complex II is triclinic, with space group P 1 and lattice parameters a = 9.129(1), b = 10.489(2), c = 11.106(3) A, α = 104.90(2)°, β = 86.61(1)°, γ = 113.93(1)°, U = 938.1(5) A 3 and Z = 2. The complexes consist of [Cu(terpy)(NCO)(H 2 O)] + and NO 3 − or PF 6 − ions. The [Cu(terpy)(NCO)(H 2 O)] + cationic units are stacked to make a chain or dimeric arrangements for the nitrate and hexafluorophosphate compounds, respectively. Magnetic susceptibility measurements (2–100 K) and EPR spectra provide evidence of the existence of very weak antiferromagnetic exchange coupling for both complexes. The magnetic behaviour is discussed on the basis of the structural findings.

Enhancement of the Luminescent Properties of a New Red-Emitting Phosphor, Mn2(HPO3)F2, by Zn Substitution

The Mn(2)(HPO(3))F(2) phase has been synthesized as single crystals by using mild hydrothermal conditions. The compound crystallizes in the orthorhombic Pnma space group, with unit cell parameters of a = 7.5607(8), b = 10.2342(7), and c = 5.5156(4) Å, with Z = 4. The crystal structure consists of a three-dimensional framework formed by alternating (010) layers of [MnO(3)F(3)] octahedra linked up by three connected [HPO(3)] tetrahedra. Luminescence measurements were performed at different temperatures between 10 and 150 K. The 10 K emission spectrum of the octahedrally coordinated Mn(II) cation exhibits a broad band centered at around 615 nm corresponding to the (4)T(1) → (6)A(1) transition. In order to explore the effect of the Mn(II) concentration and the possibility of enhancing the luminescence properties of the Mn(II) cation in Mn(2)(HPO(3))F(2), different intermediate composition members of the finite solid solution with the general formula (Mn(x)Zn(1-x))(2)(HPO(3))F(2) were prepared and their luminescent properties studied. The magnetic and specific heat behavior of M(2)(HPO(3))F(2) (M = Mn, Fe) have also been investigated. The compounds exhibit a global antiferromagnetic ordering with a spin canting phenomenon detected at approximately 30 K. The specific heat measurements show sharp λ-type peaks at 29.7 and 33.5 K for manganese and iron compounds, respectively. The total magnetic entropy is consistent with spin S = 5/2 and S = 2 of Mn(II) and Fe(II) cations.

Synthesis, crystal structure and spectroscopic properties of the NH4NiPO4·nH2O (n= 1,6) compounds; magnetic behaviour of the monohydrated phase

NH4NiPO4·6H2O and NH4NiPO4·H2O have been obtained by adding different concentrations of H3PO4 to dilute solutions of NiCl2·6H2O with special attention to the control of the pH in the solvent medium, which was regulated by addition of NH4OH. The NH4NiPO4·6H2O compound crystallizes in the orthorhombic Pmn21space group with cell parameters a= 6.9032(8), b= 6.0907(5) and c= 11.1402(8)A, V= 468.39(7)A3, Z= 2, R= 23 and Rw= 2.3%. The structure is three-dimensional and consists of Ni[O(w)]6 octahedra [O(w)= oxygen from a water molecule] linked to PO4 and NH4 tetrahedra by hydrogen bonds. All polyhedra are quite regular in this compound. The NH4NiPO4·H2O phase crystallizes in the Pmn2l space group with cell parameters a= 5.5698(2), b= 8.7668(2) and c= 4.7460(2)A. The structure of this compound has been refined with the Rietveld method using the coordinates of the KMnPO4·H2O phase as a starting model. The final residual factors were Rwp= 7.37, RB= 2.68%. The structure is formed from sheets of distorted NiO6 corner-sharing octahedra bridged through the oxygen atoms of the phosphate tetrahedra. These layers are pillared along the b direction and are interconnected by hydrogen bonds with the NH4+ cations, which are inserted between the sheets. The spectroscopic properties of both compounds are in good agreement with the symmetry observed in each phase. The values of the nephelauxetic ratio, β, are 0.89 and 0.94 for the hexahydrated and monohydrated compounds respectively. Magnetic susceptibility and specific heat results obtained for NH4NiPO4·H2O show an essentially two-dimensional antiferromagnetic exchange coupling, which becomes of a more three-dimensional behaviour with decreasing temperature.