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Dimeric [Mn(salpn)NCS] 2 (1) and polymeric [Mn(salpn)NCS] n (2) are formed by the reaction of Mn(CH 3 CO 2 ) 2 . 4H 2 0, the schiff base, and thiocyanate. The formation of the two polymorphic forms is solvent and temperature dependent. 1: orthorhombic, space group Pbca, with a = 12.573(2) A, b = 13.970(7) A, c = 18.891(9) A, and Z = 8. 2: orthorhombic, space group Pna2 1 , with a = 12.5277(14) A, b = 11.576(2) A, c = 11.513(2) A, and Z= 4. The dimers in 1 are held together by weak noncovalent S...π (phenyl) interactions leading to a chain along the a-axis. Each monomeric unit of the polymer in 2 is related to its adjacent ones by a 2-fold screw axis leading to a helix along the c-axis. The exchange coupling is nondetectable in the dimer. The magnetic susceptibility of the helical chain fits a classical chain law with J = -3.2 cm - 1 and shows a weak ferromagnetic ordering below 7 K due to spin canting effects.

Crystal structures of the three isomeric compounds Ag(2-amp)ClO4 (1), Ag(3-amp)ClO4 (2), and Ag(4-amp)ClO4 (3) reveal different packing arrangements of one-dimensional (1-D) infinite chain coordination polymers, formed in each case by the coordination of Ag to the pyridine N and amino N atoms from two different ligand molecules. 1: triclinic, space group P1, with a = 7.672(6) A, b = 11.1401(11) A, c = 11.322(4) A, α = 91.207(14)°, β = 105.52(4)°, γ = 90.48(2)°, and Z = 2. 2: monoclinic, space group P21/c, with a = 8.345(4) A, b = 8.6748(7) A, c = 26.056(9) A, β = 97.96(4)°, and Z = 4. 3: hexagonal, space group P6522, with a = 9.3154(11) A, c = 39.313(5) A, and Z = 12. 1 consists of zigzag chains, while 2 is made up of triple helical chains generating a tunnel space large enough to hold half the anions inside it. 3 has a highly symmetrical arrangement of 12 crystallographically equivalent chains held by weak Ag···Ag bonds. The crystal packing of the 1-D polymers in this case may be described in terms o...

Treatment of an aqueous solution of copper(II) acetate, dafone, and KI with I2 in CH2Cl2 leads to the formation of Cu(dafone)3I12 (1). 1 crystallizes in the orthorhombic system, space group Pbcn, with a = 22.902(4) A, b = 11.104(2) A, c = 18.992(7) A, and Z = 4. Cu(dafone)32+ is the first tris chelate of dafone and is stabilized by a channel-forming network of planar I122- ions. Temperature dependence of the EPR spectrum indicates fluxionality of the cation.

[DafoneH 2 ][(CuCl 3 H 2 O)HCl (dafone=4,5-diazafluoren-9-one) crystallizes in the monoclinic space group P2 1 /c with a=14.585(2) A, b=14.143(7) A, c=7.076(6) A, β=91.3(2) o , and Z=4. The crystal contains the unusual chromophore [(CuCl 3 H 2 O)Cl] 2- showing coordinated water and a semicoordinate Cl - . Moderately strong antiferromagnetic exchange (J=-72.8 K, with H ex =-2JS 1 S 2 ) is present. The exchange pathway appears to be via an H-bond involving H 2 O and Cl - of inversion-related molecules

Mn 2 (μ-O) 2 (μ-OAc)(H 2 O) 2 (bipy) 2 ] (ClO 4 ) 3 .H 2 O crystallizes in the monoclinic system, space group P2 1 /n (No.14) with Z=4 and a=13.619(1) A, b=16213(2) A, c=16.266(1) A, and β=113.08 (1) o . The structure was solved by direct methods and refined to conventional agreement indices R=0.021 and R w =0.024 with 5159 unique reflections for which I>3σ (I). The structure consists of binuclear [Mn IV 2 (μ-O) 2 (μ-OAc)(H 2 O) 2 (bipy) 2 ] 3+ cation separated by ClO 4 - anions and a molecule of water of crystallization

A series of new heterometallic compounds containing cerium(IV) and lanthanide(III) with pyridine-2,6-dicarboxylic acid (dipicH(2)) have been synthesized. Depending on the Ln(III) ion and preparation conditions, we obtained four types of compounds. Type-I: one-dimensional coordination polymer, [Ln(dipicH)(H(2)O)(4)Ce(dipic)(3)].7H(2)O; Ln = La (1), Ce (2), or Pr (3). Type-II: ionic compound, [Ln(dipicH)(H(2)O)(6)][Ce(dipic)(3)].7H(2)O; Ln = Nd (4), Sm (5), Eu (6), Gd (7), or Dy (8). Type-III: octanuclear cluster incorporating a six-membered coordination ring, [Ln(H(2)O)(7)Ln(dipic)(H(2)O)(4)(Ce(dipic)(3))(2)](2).nH(2)O; Ln = La (9) n = 24, Ce (10) n = 24, Pr (11) n = 24, or Nd (12) n = 26. Type-IV: hexanuclear cluster incorporating a four-membered coordination ring, [(Ln(H(2)O)(5))(2)(Ce(dipic)(3))(4)(2H(+))].nH(2)O; Ln = Nd (13) n = 34, Sm (14) n = 26, Eu (15) n = 26, or Gd (16) n = 26. Crystal structures were determined for compounds 1-16. Tb and heavier lanthanides all form compounds isomorphous with Type-IV compounds. The observed structural variety is a consequence of the interplay of lanthanide contraction and kinetic effects involving water molecules, free as well as clusters, ranging in size from 6 to 26. A metal-centered luminescence sensitized by dipic ligand was observed in compounds containing Eu(III) and Dy(III) ions. Direct chelation, as opposed to bridging coordination, leads to enhanced luminescence. Resolved EPR spectra were observed for the Gd(III) compounds which are dependent on the coordination environment.

The reaction of (NH4)2Ce(NO3)6 and CaCl2 with dipicH2 resulted in the title compound (1). 1 crystallizes in the triclinic system, space group P1, with a = 11.234(2) A, b = 12.719(4) A, c = 16.142(4) A, α = 95.63(2)°, β = 103.73(2)°, γ = 113.83(2)°, and Z = 2. The structure consists of Ce(dipic)32- and Ca(dipicH2)(OH2)32+ ions linked by carboxylate groups forming an infinite linear chain having alternating tricapped trigonal prismatic and square antiprismatic polyhedra.

Reaction between Ag(I) salts and the three isomers of (aminomethyl)pyridines, viz., 2-amp, 3-amp, and 4-amp, lead to either discrete or polymeric (1-D and 2-D) structures influenced by anions and closed shell Ag.Ag contacts. Characterization data for Ag(2-amp)BF(4) (1) follow: monoclinic, space group C2/c, with a = 16.788(2) A, b = 11.5719(6) A, c = 11.3864(7) A, beta = 123.671(8) degrees, and Z = 8. For Ag(2)(2-amp)(3)(PF(6))(2) (2): monoclinic, space group P2(1)/a, with a = 10.029(7) A, b = 20.291(12) A, c = 13.907(6) A, beta = 95.38(5) degrees, and Z = 4. For Ag(2)(3-amp)(3)(PF(6))(2) (4): triclinic, space group P1, with a = 10.4482(7) A, b = 11.1468(9) A, c = 12.2720(11) A, alpha = 81.018(7) degrees, beta = 80.668(6) degrees, gamma = 80.977(6) degrees, and Z = 2. For Ag(4-amp)BF(4).0.75CH(3)CN (5): orthorhombic, space group C222(1), with a = 9.272(2) A, b = 16.164(12) A, c = 27.851(2) A, and Z = 8. For Ag(4-amp)PF(6) (6): monoclinic, space group P2(1)/m, with a = 5.2089(7) A, b = 14.3950(17) A, c = 7.0149(14) A, beta = 96.538(14) degrees, and Z = 2. While Ag(I) is 2-coordinate in 1, 5 and 6, it shows 3-coordination in 2 and 4. Compound 1 consists of a 1-D polymeric cation chain with interchain Ag...Ag contacts and the anions sitting on the edges of the chains. The dication in 2 is held in the form of a circular helicate by closed shell Ag...Ag interactions. Compound 4 generates a 2-D network with channels big enough to accommodate the anions. Compound 5 is a 2-D chiral network of chains connected by Ag...Ag contacts. Compound 6 shows a simple 1-D chain structure with an alternating arrangement of cationic chains and anions.

The trinuclear manganese complex [Mn(3)O(4)(phen)(4)(H(2)O)(2)](NO(3))(4).2.5H(2)O, 1 (where, phen = 1,10-phenanthroline), has been synthesized by the Ce(IV) oxidation of a concentrated solution of manganese(II) acetate and phen in 1.6 N nitric acid. The complex crystallizes in the triclinic space group Ponemacr; with a = 10.700(2) Å, b = 12.643(3) Å, c = 20.509(4) Å, alpha = 78.37(3) degrees, beta = 83.12(3) degrees, gamma = 82.50(3) degrees, and Z = 2. The structure was solved by direct methods and refined by least-squares techniques to the conventional R (R(w)) factors of 0.055 (0.076) based on 4609 unique reflections with F(o)/= 6.0sigma(F(o)). The structure of the cation consists of an oxo-bridged Mn(3)O(4)(4+) core, with the geometry of the manganese atoms being octahedral. The coordination polyhedron of one of the manganese atoms (Mn(1)) consists of twomgr; oxo ligands and two pairs of nitrogen atoms of two phen moieties, whereas that of each of the remaining two manganese atoms consists of threemgr;-oxo ligands, two nitrogen atoms of a phen moiety, and the oxygen atom of a water molecule. The complex represents the second example for water coordination to manganese(IV) centers in complexes with a Mn(3)O(4)(4+) core. Optical spectra in ligand buffer (pH 4.5) reveal complete conversion of the complex into a Mn(III)Mn(IV) species. The observed room-temperature (298 K) magnetic moment of 3.75mgr;(B) indicates the presence of strong antiferromagnetic coupling in the complex.

Mise en evidence d'une delocalisation etendue incluant l'ion nitrate. Evaluation des parametres de liaison en utilisant les parametres RPE et les energies de transition electronique. Comparaison des stabilites redox des complexes d'argent et de cuivre