Synthesis and Uncommon Structural Characterization of Novel Zinc and Cadmium Complexes with Imino Nitroxide Radical

Two novel complexes {[Zn(IM4py)2(tp)(H2O)]·2H2O}n 1 and {[Cd(IM4py)2(tp)- (H2O)]·1.25H2O}n 2 (IM4py = 2-(4'-pyridinyl)-4,4,5,5-tetramethylimidazoline-1-oxyl and tp = terephthalate dianion) have been synthesized and characterized by elemental analyses, IR spectrum and single-crystal X-ray diffraction. Crystal data for complex 1: monoclinic, space group C2/c, a = 20.648(7), b = 12.130(4), c = 14.036(4) , β = 106.351(5)o, C32H42N6O9Zn, Mr = 720.09, V = 3373.3(2) 3, Z = 4, Dc = 1.418 g/cm3, μ(MoKα) = 0.790 mm-1, F(000) = 1512, the final R = 0.0407 and wR = 0.0894 for 3480 independent reflections with Rint = 0.0432. Crystal data for complex 2: monoclinic, space group C2/c, a = 21.332(6), b = 12.063(3), c = 14.246(4) , β = 106.704(4)o, C32H40.50N6O8.25Cd, Mr = 753.60, V = 3511.2(2) 3, Z = 4, Dc = 1.426 g/cm3, μ(MoKα) = 0.679 mm-1, F(000) = 1554, the final R = 0.0419 and wR = 0.0961 for 3627 independent reflections with Rint = 0.0440. The framework structures of complexes 1 and 2 are 3-D networks via the hydrogen bonds among 1-D chains. The notable characteristics of the two complexes are that the coordination polyhedron of Zn(II) adopts a rare distorted five-coordinate square pyramidal geometry in 1, and the Cd(II) complex exhibits an unusual distorted seven-coordinate pentagonal bipyramid in 2.     

Synthesis and Crystal Structure of Dicopper(II) Compound Containing Oxalate and Reduced Imino Nitroxide Radicals

1 INTRODUCTION There has been increasing interest in molecular- based magnetic materials, in which the combination of metal ions and organic radicals are used to construct assembled systems[1, 2]. Nitroxide radicals are normally used as spin carriers …     

A Cu(II) Complex with IM-MeImz-κ~2 N,O Mode in [Cu(IM-MeImz)_2]·(SCN)_2: Synthesis, Crystal Structure and Magnetic Properties

A new copper(II) compound with imino nitroxide radicals [Cu(IM-MeImz)2]?(SCN)2 (IM-meImz =2-(5-methylimidazol-4-yl)-4,4,5,5-tetramethyl-2-imidazoline-1-oxyl) has been synthesized and characterized structurally and magnetically. It crystallizes in monoclinic, space group P21/c with a = 9.3604(7), b = 10.3012(7), c = 16.6684(12) , β = 105.0290(10)o, V = 1552.25(19) 3, C24H34CuN10O2S2, Mr = 622.27, Z = 2, Dc = 1.331 g/cm3, μ(MoKα) = 0.876 mm-1, F(000) = 650, the final R = 0.0374 and wR = 0.1079. X-ray analysis demonstrates that the IM-MeImz ligand is coordinated to the copper(II) ion as an unusual didentate chelate with a κ2 N(MeImz),O(IM) mode in the complex. The square-planar coordination sites at Cu(II) are occupied by two O and two N atoms from the imino nitroxide radicals. The complex molecules are connected as a onedimensional polymer structure by intermolecular interactions. Magnetic measurements show that there are intramolecular antiferromagnetic interactions between the Cu(II) ion and radicals.     

Crystal structures and magnetic properties of metal complexes bearing four nitronyl nitroxide moieties in the same coordination sphere

Mononuclear transition metal complexes of the type [M(2,6-NITpy)2](ClO4)2 x solvent (2,6-NITpy = 2,6-bis-(3'-oxide-1'-oxyl-4',4',5',5'-tetramethylimidazolin-2'-yl)pyridine; M = Ni (1), Co (2), Zn (3), Mn (4), Cu (5)) have been synthesized and characterized by single-crystal X-ray diffraction studies. Crystal data: 1, monoclinic, P2(1)/c, Z = 4, a = 20.946(2) A, b = 12.0633(2) A, c = 21.173(2) A, beta = 113.55(1) degrees; 2, monoclinic, P2(1)/c, Z = 4, a = 20.902(2) A, b = 12.0981(8) A, c = 21.215(2) A, beta = 113.130(9) degrees; 3, triclinic, P1, Z = 2, a = 11.410(1) A, b = 12.932(1) A, c = 21.609(2) A, alpha = 96.040(2) degrees, beta = 102.24(1) degrees, gamma = 114.98(1); 4, monoclinic, P2(1)/n, Z = 4, a = 11.5473(8) A, b = 19.212(1) A, c = 25.236(2) A, beta = 98.772(9) degrees; 5, triclinic, P1, Z = 2, a = 12.1604(9) A, b = 12.6961(9) A, c = 18.103(2) A, alpha = 84.191(8) degrees, beta = 73.392(8) degrees, gamma = 66.072(8). The two 2,6-NITpy biradicals behave as terdentate ligands and bind almost perpendicular to each other in meridional positions. In compounds 1-4, the pyridine rings are axially ligated and four different nitronyl nitroxide radicals bind to the metal center through their O(nitroxyl) atoms, forming the equatorial plane of a distorted octahedron. On the contrary, in the copper(II) complex (5), the two N(pyridyl) atoms are found in equatorial positions. Only two nitroxide groups are then bound to the copper(II) ion in the equatorial plane, the other two being axially ligated. The two axially bound nitronyl nitroxide radicals couple ferromagnetically to the copper center (JCu-rad(ax) = + 10 K), whereas a strong antiferromagnetic coupling between this metal ion and the equatorial nitroxide groups (JCu-rad(eq) = -460 K) is observed. The other complexes exhibit strong antiferromagnetic metal-radical interactions: JNi-rad = -240 K, for 1; JMn-rad = -120 K, for 4. Interestingly, the study of the diamagnetic zinc(II) compound (3) reveals a moderate intramolecular antiferromagnetic interaction between radicals coordinated to the same metal center (Jrad-rad = -27.7 K). This interaction is transmitted through space and is also present in the other complexes: Jrad-rad = -14 K, for 1; Jrad-rad = -10 K, for 4; Jrad-rad = -20.5 K, for 5. Antiferromagnetic intermolecular interactions are also present in all the complexes herein studied.     

Coordination Compounds of Schiff-Base Ligands Derived from Diaminomaleonitrile (DMN): Mononuclear, Dinuclear, and Macrocyclic Derivatives

Copper(II) and V(IV)O complexes of an open chain (1:2) Schiff-base ligand (H(2)L1), derived by the template condensation of diaminomaleonitrile (DMN) and salicylaldehyde, and dicopper(II) complexes of (2:2) macrocyclic Schiff-base ligands derived by template condensation of diformylphenols and diaminomaleonitrile, have been synthesized and studied. Structures have been established for the first time for mononuclear Cu(II) and V(IV)O derivatives of the open chain ligand H(2)L1 (1:2), a dinuclear macrocyclic Cu(II) complex derived from a 2:2 macrocyclic ligand (H(2)M1), and the half-condensed 1:1 salicylaldehyde ligand (H(2)L2). [Cu(L1)] (1) (L1 = C(18)H(10)N(4)O(2)) crystallized in the monoclinic system, space group P2(1)/n (No. 14), with a = 11.753(6) ?, b = 7.708(5) ?, c = 16.820(1) ?, and Z = 4. [VO(L1)(DMSO] (2) crystallized in the orthorhombic system, space group Pbca (No. 61), with a = 22.534(9) ?, b = 23.31(1) ?, c = 7.694(5) ?, and Z = 8. H(2)L2 (C(18)H(8)N(4)O) (3) crystallized in the monoclinic system, space group P2(1)/c (No. 14), with a = 13.004(6) ?, b = 11.441(7) ?, c = 7.030(4) ?, and Z = 4. [Cu(2)(M3)](CH(3)COCH(3)) (4) (M3 = C(32)H(24)N(8)O(4)) crystallized in the monoclinic system, space group C2/c (No. 15), with a = 38.33(2) ?, b = 8.059(4) ?, c = 22.67(2) ?, and Z = 8. [Cu(L3)(DMSO)] (5) (L3 = C(20)H(14)N(2)O(4)) crystallized in the triclinic system, space group P&onemacr; (No. 2), with a = 10.236(4) ?, b = 13.514(4) ?, c = 9.655(4) ?, and Z = 2. 4 results from the unique addition of two acetone molecules to two imine sites in [Cu(2)(M1)](ClO(4))(2) (M1 = 2:2 macrocyclic ligand derived from template condensation of DMN and 2,6-diformyl-4-methylphenol). 4 has extremely small Cu-OPh-Cu bridge angles (92.0, 92.8 degrees ), well below the expected lower limit for antiferromagnetic behavior, but is still antiferromagnetically coupled (-2J = 25.2 cm(-)(1)). This behavior is associated with a possible antiferromagnetic exchange term that involves the conjugated framework of the macrocyclic ligand itself. The ligand L3 in 5 results from hydrolysis of M1 on recrystallization of [Cu(2)(M1)](ClO(4))(2) from undried dimethyl sulfoxide.     

Intermolecular Ferromagnetic and Antiferromagnetic Interactions in Halogen-Bridged Copper(I) Imino Nitroxides: Crystal Structures and Magnetic Properties of [Cu(I)(&mgr;-X)(imino nitroxide)](2) (X = I or Br)

Reaction of CuI or CuBr with some imino nitroxides in methanol gave the halogen bridged dinuclear Cu(I) complexes [Cu(&mgr;-I)(impy)](2) (1), [Cu(&mgr;-I)(immepy)](2) (2), [Cu(&mgr;-Br)(immepy)](2) (3), and [Cu(&mgr;-Br)(imph-NO(2))](2) (4), respectively (impy = 2-(2'-pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl, immepy = 2-(6'-methyl-2'-pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl, imph-NO(2) = 2-(4'-nitrophenyl)-4,4,5,5-tetramethyl-4,6-dihydro-1H-imidazolyl-1-oxyl). Crystal structures and magnetic properties have been studied. Complexes 1-4 have dimeric structures where two copper ions are doubly bridged by halide ions in a &mgr;(2) fashion. In 1-3, each copper ion is tetrahedral with a bidentate imino nitroxide and two halide ions, and the two copper ions are separated by 2.592(2), 2.6869(8), and 2.7357(6) ?, respectively. In 4, triangular coordination sites of the copper ions are completed with a nitrogen atom from the imino nitroxide and two bromide ions bridging the two copper ions with a separation of 3.074(2) ?. Ligand imino nitroxides in 1-4 form one-dimensional radical chains, and the chains are linked with halocuprate dimer units. Structural and magnetic susceptibility data support that radicals in 1 and 4 are ferromagnetically stacked, while radicals in 2 and 3 form an antiferromagnetic chain. The magnetic behaviors are discussed in connection with the stacking modes of the radicals and bridging conformations. Crystal data (Mo Kalpha, lambda = 0.71069 ?): 1, orthorhombic, space group P2(1)2(1)2(1), a = 17.807(2) ?, b = 8.595(2) ?, c = 19.336(6) ?, and Z = 4; 2, monoclinic, space group P2(1)/c, a = 9.941(2) ?, b = 18.482(2) ?, c = 8.337(2) ?, beta = 96.41(2) degrees, and Z = 2; 3, monoclinic, space group P2(1)/c, a = 9.964(6) ?, b = 18.167(4) ?, c = 8.009(7) ?, beta = 95.81(6) degrees, and Z = 2; 4, monoclinic, space group P2(1)/c, a = 11.991(7) ?, b = 17.998(8) ?, c = 7.215(6) ?, beta = 104.07(6) degrees, and Z = 2.     

Dinuclear (Fe(II), Gd(III)) complexes deriving from hexadentate Schiff bases: synthesis,structure, and Mössbauer and magnetic properties

The dinuclear (Fe(II), Gd(III)) complexes studied in this report derive from hexadentate Schiff base ligands abbreviated H(2)L(i)() (i = 1, 2, 3). H(2)L(1) = N,N'-bis(3-methoxysalicylidene)-1,3-diamino-2,2'-dimethyl-propane, H(2)L(2) = N,N'-bis(3-methoxysalicylidene)-1,2-diamino-2-methylpropane, and H(2)L(3) = N,N'-bis(3-methoxysalicylidene)-1,2-diaminoethane. The crystal and molecular structures of three complexes have been determined at 160 K. Depending on the solvent used in the preparation, L(1)Fe(CH(3)OH)Gd(NO(3))(3)(CH(3)OH)(2), 1, or L(1)Fe((CH(3))(2)CO)Gd(NO(3))(3), 1', is obtained from H(2)L(1). A similar complex, L(2)Fe((CH(3))(2)CO)Gd(NO(3))(3), 2, is obtained from H(2)L(2). Complex 1 crystallizes in the orthorhombic space group Pca2(1) (No. 29): a = 22.141(3) A, b = 9.4159(16) A, c = 15.2075(17) A, V = 3170.4(7) A(3), Z = 4. Complexes 1' and 2 crystallize in the monoclinic space group P2(1)/c (No. 14): 1', a = 9.6264(17) A, b = 19.662(3) A, c = 16.039(3) A, beta = 95.15(2) degrees, V = 3023.6(9) A(3), Z = 4; 2, a = 9.7821(13) A, b = 18.7725(17) A, c = 16.100(2) A, beta = 96.497(16) degrees, V = 2937.5(6) A(3), Z = 4. Complexes 1, 1', and 2 possess an Fe(O(phenoxo))(2-)Gd core. The mononuclear L(3)Fe complex could be prepared from H(2)L(3) but not the related dinuclear (Fe, Gd) species. M?ssbauer spectroscopy evidences that the iron center is in the +2 oxidation state for the six complexes. The experimental magnetic susceptibility and magnetization data of complexes 1, 1', and 2 indicate the occurrence of weak Fe(II)-Gd(III) ferromagnetic interactions. Single ion zero-field splitting of the iron(II) must be taken into account for satisfactorily fitting the data by exact calculation of the energy levels associated to the spin Hamiltonian through diagonalization of the full matrix for axial symmetry (1, J = 0.50 cm(-1), D = 2.06 cm(-1); 1', J = 0.41 cm(-1), D = 3.22 cm(-1); 2, J = 0.08 cm(-1), D = 4.43 cm(-1)).     

Verdazyl radicals as oligopyridine mimics: structures and magnetic properties of M(II) complexes of 1,5-dimethyl-3-(2,2'-bipyridin-6-yl)-6-oxoverdazyl (M = Mn,Ni, Cu,Zn)

The verdazyl radical 1,5-dimethyl-3-(2,2'-bipyridin-6-yl)-6-oxoverdazyl (3) was prepared, and its homoleptic metal complexes M(3)(2)(2+).2X(-) (5, M = Mn(II); 6, M = Ni(II); 7, M = Cu(II); 8, M = Zn(II); X = ClO(4), PF(6)) were characterized by single-crystal X-ray diffraction and variable-temperature magnetic susceptibility measurements. Relevant crystallographic parameters are as follows: 5, monoclinic space group Pna2(1), a = 18.755(4) A, b = 11.154(3) A, c = 16.594(4) A, alpha = 90.00 degrees, beta = 90.00 degrees, gamma = 90.00 degrees, V = 3471.4(13) A(3), and Z = 4; 7, triclinic space group Ponedblac;, a = 9.4638(18) A, b = 9.8442(19) A, c = 18.769(4) A, alpha = 103.746(3) degrees, beta = 92.925(3) degrees, gamma = 94.869(3) degrees, V = 1687.8(6) A(3), and Z = 2; 8, triclinic space group Ponedblac;, a = 9.4858(14) A, b = 9.7919(14) A, c = 18.889(3) A, alpha = 104.196(3) degrees, beta = 92.855(3) degrees, gamma = 94.216(3) degrees, V = 1692.1(4) A(3), and Z = 2. In all cases, the two verdazyl-based ligands bind almost perpendicular to each other in meridional positions, yielding pseudooctahedral metal complexes whose general structural features are strongly reminiscent of metal bis(terpyridine) complexes. The intramolecular metal-verdazyl magnetic exchange coupling is strongly ferromagnetic in 6 (J(Ni-vd) = +240 cm(-1)), and strongly antiferromagnetic in 5 (J(Mn-vd) = -93 cm(-1)). Complex 7 exhibits weak ferromagnetic coupling (J(Cu-vd) = -4.5 cm(-1)). Intramolecular radical-radical coupling in the zinc complex 8 was found to be weakly antiferromagnetic (J(vd-vd) = -8 cm(-1)). Intramolecular radical-radical exchange was generally weak in the four metal complexes, ranging from -10 cm(-1) (for 5) to +2 cm(-1) (for 7). The low-temperature magnetic behavior of 7 and 8 is complex, possibly arising from a combination of intra- and intermolecular interactions.     

The unprecedented preparation of dinuclear zinc(II) complexes from 4-halido-2-[(3-cyclohexylaminopropylimino)methyl]phenol

Three new centrosymmetric trinuclear nickel(II) and manganese(II) complexes, Ni[Ni(CH(3)COO)(CPA)](2) (1), Ni[Ni(CH(3)COO)(BPA)](2) (2), Mn[Mn(CH(3)COO)(BPA)](2) (3), where H(2)CPA = N,N'-bis(5-chlorosalicylidene)-1,3-propanediamine, H(2)BPA = N,N'-bis(5-bromosalicylidene)-1,3-propanediamine, and two new centrosymmetric dinuclear zinc(II) complexes, [Zn(2)(CMP)(2)] (4) and [Zn(2)(BMP)(2)] (5), where H(2)CMP = 4-chloro-2-{[3-(5-chloro-2-hydroxybenzyl)aminopropylimino]methyl}phenol, and H(2)BMP = 4-bromo-2-{[3-(5-bromo-2-hydroxybenzyl)aminopropylimino]methyl}phenol, have been prepared from the Schiff bases derived from 5-halido-substituted salicylaldehydes with N-hexylpropane-1,3-diamine under solvothermal conditions. The complexes have been characterised by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction studies. The complexes 1, 2, and 3 crystallise in the monoclinic space group P2(1)/c with cell dimensions a = 9.347(1), b = 11.507(2), c = 18.539(2) ?, β = 93.774(2)°, Z = 2 (for 1), a = 9.111(4), b = 12.089(6), c = 18.724(8) ?, β = 92.117(7)°, Z = 2 (for 2), and a = 11.328(2), b = 22.468(5), c = 8.270(2) ?, β = 93.74(3)°, Z = 2 (for 3), while complexes 4 and 5 crystallise in the triclinic space group P1, with cell dimensions a = 7.483(1), b = 9.990(2), c = 12.155(2) ?, α = 75.27(3), β = 85.00(3), γ = 73.82(3)°, Z = 1 (for 4), and a = 7.008(1), b = 10.081(2), c = 13.095(3) ?, α = 100.62(3), β = 95.51(3), γ = 104.03(3)°, Z = 1 (for 5). It is interesting that the mono-Schiff bases 4-chloro-2-[(3-cyclohexylaminopropylimino)methyl]phenol (HCCP) and 4-bromo-2-[(3-cyclohexylaminopropylimino)methyl]phenol (HBCP) used to prepare the nickel(II) and manganese(II) complexes were transferred to bis-Schiff bases H(2)CPA and H(2)BPA in the complexes 1, 2, and 3, while the mono-Schiff bases HCCP and HBCP used to prepare the zinc(II) complexes were transferred to novel ligands H(2)CMP and H(2)BMP, bearing the unexpected, newly formed carbon-nitrogen single bond.     

Novel metal-organic frameworks with specific topology from new tripodal ligands: 1,3,5-tris(1-imidazolyl)benzene and 1,3-bis(1-imidazolyl)-5-(imidazol-1-ylmethyl)benzene

Reactions of two new tripodal ligands 1,3,5-tris(1-imidazolyl)benzene (4) and 1,3-bis(1-imidazolyl)-5-(imidazol-1-ylmethyl)benzene (5) with metal [Ag(I), Cu(II), Zn(II), Ni(II)] salts lead to the formation of novel two-dimensional (2D) metal-organic frameworks [Ag(2)(4)(2)][p-C(6)H(4)(COO)(2)].H(2)O (6), [Ag(4)]ClO(4) (7), [Cu(4)(2)(H(2)O)(2)](CH(3)COO)(2).2H(2)O (8), [Zn(4)(2)(H(2)O)(2)](NO(3))(2) (9), [Ni(4)(2)(N(3))(2)].2H(2)O (10), and [Ag(5)]ClO(4) (11). All the structures were established by single-crystal X-ray diffraction analysis. Crystal data for 6: monoclinic, C2/c, a = 23.766(3) A, b = 12.0475(10) A, c = 13.5160(13) A, beta = 117.827(3) degrees, Z = 4. For compound 7: orthorhombic, P2(1)2(1)2(1), a = 7.2495(4) A, b = 12.0763(7) A, c = 19.2196(13) A, Z = 4. For compound 8: monoclinic, P2(1)/n, a = 8.2969(5) A, b = 12.2834(5) A, c = 17.4667(12) A, beta = 96.5740(10) degrees, Z = 2. For compound 9: monoclinic, P2(1)/n, a =10.5699(3) A, b = 11.5037(3) A, c = 13.5194(4) A, beta = 110.2779(10) degrees, Z = 2. For compound 10: monoclinic, P2(1)/n, a = 9.8033(3) A, b = 12.1369(5) A, c = 13.5215(5) A, beta = 107.3280(10) degrees, Z = 2. For compound 11: monoclinic C2/c, a = 18.947(2) A, b = 9.7593(10) A, c = 19.761(2) A, beta = 97.967(2) degrees, Z = 8. Both complexes 6 and 7 are noninterpenetrating frameworks based on the (6, 3) nets, and 8, 9 and 10 are based on the (4, 4) nets while complex 11 has a twofold parallel interpenetrated network with 4.8(2) topology. It is interesting that, in complexes 6,7, and 11 with three-coordinated planar silver(I) atoms, each ligand 4 or 5 connects three metal atoms, while in the case of complexes 8, 9, and 10 with six-coordinated octahedral metal atoms, each ligand 4 only links two metal atoms, and another imidazole nitrogen atom of 4 did not participate in the coordination with the metal atoms in these complexes. The results show that the nature of organic ligand and geometric needs of metal atoms have great influence on the structure of metal-organic frameworks.     

Synthesis and characterization of six new quaternary actinide thiophosphate compounds: Cs(8)U(5)(P(3)S(10))(2)(PS(4))(6)(,) K(10)Th(3)(P(2)S(7))(4)(PS(4))(2), and A(5)An(PS(4))(3), (A = K, Rb, Cs; An = U, Th)

Six new actinide metal thiophosphates have been synthesized by the reactive flux method and characterized by single-crystal X-ray diffraction: Cs(8)U(5)(P(3)S(10))(2)(PS(4))(6) (I), K(10)Th(3)(P(2)S(7))(4)(PS(4))(2) (II), K(5)U(PS(4))(3) (III), K(5)Th(PS(4))(3) (IV), Rb(5)Th(PS(4))(3) (V), and Cs(5)Th(PS(4))(3) (VI). Compound I crystallizes in the monoclinic space group P2(1)/c with a = 33.2897(1) A, b = 14.9295(1) A, c = 17.3528(2) A, beta = 115.478(1) degrees, Z = 8. Compound II crystallizes in the monoclinic space group C2/c with a = 32.8085(6) A, b = 9.0482(2) A, c = 27.2972(3) A, beta = 125.720(1) degrees, Z = 8. Compound III crystallizes in the monoclinic space group P2(1)/c with a = 14.6132(1) A, b = 17.0884(2) A, c = 9.7082(2) A, beta = 108.63(1) degrees, Z = 4. Compound IV crystallizes in the monoclinic space group P2(1)/n with a = 9.7436(1) A, b = 11.3894(2) A, c = 20.0163(3) A, beta = 90.041(1) degrees, Z = 4, as a pseudo-merohedrally twinned cell. Compound V crystallizes in the monoclinic space group P2(1)/c with a = 13.197(4) A, b = 9.997(4) A, c = 18.189(7) A, beta = 100.77(1) degrees, Z = 4. Compound VI crystallizes in the monoclinic space group P2(1)/c with a = 13.5624(1) A, b = 10.3007(1) A, c = 18.6738(1) A, beta = 100.670(1) degrees, Z = 4. Optical band-gap measurements by diffuse reflectance show that compounds I and III contain tetravalent uranium as part of an extended electronic system. Thorium-containing compounds are large-gap materials. Raman spectroscopy on single crystals displays the vibrational characteristics expected for [PS(4)](3)(-), [P(2)S(7)](4-), and the new [P(3)S(10)](5)(-) building blocks. This new thiophosphate building block has not been observed except in the structure of the uranium-containing compound Cs(8)U(5)(P(3)S(10))(2)(PS(4))(6).     

Magnetic Mn and Co complexes with a large polycyclic aromatic substituted nitronylnitroxide

2-(1'-Pyrenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl (PyrNN) was reacted with M(hfac)(2) (M = Mn(II) and Co(II), hfac = hexafluoracetylacetonate) to give two isostructural ML(2) stoichiometry M(hfac)(2)(PyrNN)(2) complexes and a ML stoichiometry one-dimensional (1-D) polymer chain complex [Mn(hfac)(2)(PyrNN)]. The ML(2) complexes have similar crystal structures with monoclinic unit cells, in which one NO unit from each PyrNN ligand is bonded to the transition metal on cis vertices of a distorted octahedron. The major magnetic interactions are intracomplex metal-to-radical exchange (J), and intermolecular exchange across a close contact between the uncoordinated NO units (J'). For M = Mn(II) an approximate chain model fit gives g = 2.0, J = (-)125 cm(-1) and J' = (-)49 cm(-1); for M = Co(II), g = 2.4, J = (-)180 cm(-1), and J' = (-)70 cm(-1). Hybrid density functional theory (DFT) computations modeling the intermolecular exchange by using only the radical units across the close contact are in good accord with the estimated values of J'. The chain type complex structure shows solvent incorporation for overall structure [Mn(hfac)(2)(PyrNN)](n)·0.5(CHCl(3))·0.5(C(7)H(16)). Both NO groups of the PyrNN ligand are complexed to form helical chains, with very strong metal to radical antiferromagnetic exchange that gives overall ferrimagnetic behavior.     

Proton control of oxidation and spin state in a series of iron tripodal imidazole complexes

Reaction of iron salts with three tripodal imidazole ligands, H(3)(1), H(3)(2), H(3)(3), formed from the condensation of tris(2-aminoethyl)amine (tren) with 3 equiv of an imidazole carboxaldehyde yielded eight new cationic iron(III) and iron(II), [FeH(3)L](3+or2+), and neutral iron(III), FeL, complexes. All complexes were characterized by EA(CHN), IR, UV, M?ssbauer, mass spectral techniques and cyclic voltammetry. Structures of three of the complexes, Fe(2).3H(2)O (C(18)H(27)FeN(10)O(3), a = b = c = 20.2707(5), cubic, I3d, Z = 16), Fe(3).4.5H(2)O (C(18)H(30)FeN(10)O(4.5), a = 20.9986(10), b = 11.7098(5), c = 19.9405(9), beta = 109.141(1), monoclinic, P2(1)/c), Z = 8), and [FeH(3)(3)](ClO(4))(2).H(2)O (C(18)H(26)Cl(2)FeN(10)O(9), a = 9.4848(4), b = 23.2354(9), c = 12.2048(5), beta = 111.147(1) degrees, monoclinic, P2(1)/n, Z = 4) were determined at 100 K. The structures are similar to one another and feature an octahedral iron with facial coordination of imidazoles and imine nitrogen atoms. The iron(III) complexes of the deprotonated ligands, Fe(1), Fe(2), and Fe(3), are low-spin while the protonated iron(III) cationic complexes, [FeH(3)(1)](ClO(4))(3) and [FeH(3)(2)](ClO(4))(3), are high-spin and spin-crossover, respectively. The iron(II) cationic complexes, [FeH(3)(1)]S(4)O(6), [FeH(3)(2)](ClO(4))(2), [FeH(3)(3)](ClO(4))(2), and [FeH(3)(3)][B(C(6)H(5))(4)](2) exhibit spin-crossover behavior. Cyclic voltammetric measurements on the series of complexes show that complete deprotonation of the ligands produces a negative shift in the Fe(III)/Fe(II) reduction potential of 981 mV on average. Deprotonation in air of either cationic iron(II) or iron(III) complexes, [FeH(3)L](3+or2+), yields the neutral iron(III) complex, FeL. The process is reversible for Fe(3), where protonation of Fe(3) yields [FeH(3)(3)](2+).     

Ferro- and ferrimagnetic chains of hin-bridged copper(II) and manganese(II) and hnn-bridged manganese(II) complexes (hin = 4,4,5,5-tetramethylimidazolin-1-oxyl; hnn = 4,4,5,5-tetramethylimidazolin-1-oxyl 3-oxide)

We have exploited potential utility of 4,4,5,5-tetramethylimidazolin-1-oxyl (hin) and 4,4,5,5-tetramethylimidazolin-1-oxyl 3-oxide (hnn) as mu-1,4 and mu-1,5 bridging ligands, respectively, carrying an unpaired electron in development of metal-radical hybrid magnets. X-ray diffraction measurements of [Cu(hfac)(2)hin] (1), [Mn(hfac)(2)hin] (2), and [Mn(hfac)(2)hnn] (3) revealed one-dimensional metal-radical alternating chain structures, where hfac denotes 1,1,1,5,5,5-hexafluoropentane-2,4-dionate. Magnetic measurements of 1 indicate the presence of intrachain ferromagnetic coupling between copper and radical spins. The magnetic exchange parameter was estimated as 2J/k = 56.8 K based on an S = 1/2 equally spaced ferromagnetic chain model (H = -2J summation operator S(i).S(i+1)). This ferromagnetic interaction can be explained in terms of the axial coordination of the hin nitrogen or oxygen to Cu(II). The chi(m)T value of 2 and 3 increased on cooling, and the magnetic data could be analyzed by Seiden's ferrimagnetic chain model, giving 2J/k = -325 and -740 K, respectively. The antiferromagnetic interaction of 2 and 3 can be attributed to orbital overlap between the manganese and the oxygen or nitrogen magnetic orbitals. The exchange interactions between Cu-hin and Mn-hnn are larger than those of typical Cu- and Mn-nitronyl nitroxide complexes, indicating that the choice of small ligands is a promising strategy to bestow strong exchange interaction. Compound 3 became a ferrimagnet below 4.4 K, owing to ferromagnetic coupling among the ferrimagnetic chains.     

2,6-吡啶二亚胺基锰(Ⅲ)配合物的合成、晶体结构及催化性能

由三齿含氮配体2,6-二[1-(2,6-二甲基苯基亚胺)乙基]吡啶(L1)、2,6-二[1-(2,6-二乙基苯基亚胺)乙基]吡啶(L2)和2,6-二[1-(2,4,6-三甲基苯基亚胺)乙基]吡啶(L3)分别与MnCl2·4H2O在乙腈中反应,合成了3个新的具有较大空间位阻的2,6-吡啶二亚胺基氯化锰配合物L1Mn(Ⅱ)...     

Syntheses and Crystal Structures of Two New Zinc(Ⅱ)Nitroxide Radical Complexes Bridged by Isophthalate

Two novel complexes [Zn(NIT3-py)(ip)]n 1 and [Zn(im3-py)(ip)]n 2 (NIT3-py =2-(3"-pyridyl)-4,4,5,5,-tetramethylimidazoline-1-oxyl-3-oxide, im3-py = 2-(3'-pyridyl)-4,4,5,5-te-tramethylimidazoline-1-oxyl, ip = isophthalate) have been synthesized and structurally determinedby X-ray diffraction.Crystal data for 1: C32H36N6O8Zn, Mr= 698.04, monoclinic, space group C with a = 23.600(3), b = 10.2073(12), c = 13.4027(16)(A), β= 92.586(2)°, V = 3225.3(7) (A)3, Dc=1.438 g/cm3, F(000) = 1456,μ(MoKα) = 0.822 mm-1, Z = 4, the final R = 0.0390 and wR = 0.1032 for 6037 independent reflections with Rint=0.0214.Crystal data for 2: C32H36N6O6Zn, Mr = 666.04,monoclinic, space group C2/c with a = 24.434(4), b = 13.543(2), c = 10.2379(16)(A), β= 109.024(2)°,V= 3202.8(9)(A)3, Dc= 1.381 g/cm3, F(000) = 1392,μ(MoKα) = 0.820 mm-1, Z= 4,the final R = 0.0304 and wR = 0.0658 for 2833 independent reflections with Rint = 0.0307.X-ray analysis reveals that both Zn(Ⅱ) ions are four-coordinated by two pyridyl-N atoms from nitroxide radicals and two carboxylate oxygen atoms to form distorted tetrahedral geometries.Each iso-phthalate dianion binds two Zn(Ⅱ) ions in a monodentate mode, leading to a 1-D chain structure.     

Complexation of metal ions, including alkali-earth and lanthanide(III) ions, in aqueous solution by the ligand 2,2',6',2'-terpyridyl

Some metal-ion-complexing properties of the ligand 2,2',6',2'-terpyridyl (terpy) in aqueous solution are determined by following the π-π* transitions of 2 × 10(-5) M terpy by UV-visible spectroscopy. It is found that terpy forms precipitates when present as the neutral ligand above pH ～5, in the presence of electrolytes such as NaClO(4) or NaCl added to control the ionic strength, as evidenced by large light-scattering peaks. The protonation constants of terpy are thus determined at the ionic strength (μ) = 0 to avoid precipitation and found to be 4.32(3) and 3.27(3). The log K(1) values were determined for terpy with alkali-earth metal ions Mg(II), Ca(II), Sr(II), and Ba(II) and Ln(III) (Ln = lanthanide) ions La(III), Gd(III), and Lu(III) by titration of 2 × 10(-5) M free terpy at pH >5.0 with solutions of the metal ion. Log K(1)(terpy) was determined for Zn(II), Cd(II), and Pb(II) by following the competition between the metal ions and protons as a function of the pH. Complex formation for all of these metal ions was accompanied by marked sharpening of the broad π-π* transitions of free terpy, which was attributed to complex formation affecting ligand vibrations, which in the free ligand are coupled to the π-π* transitions and thus broaden them. It is shown that log K(1)(terpy) for a wide variety of metal ions correlates well with log K(1)(NH(3)) values for the metal ions. The latter include both experimental log K(1)(NH(3)) values and log K(1)(NH(3)) values predicted previously by density functional theory calculation. The structure of [Ni(terpy)(2)][Ni(CN)(4)]·CH(3)CH(2)OH·H(2)O (1) is reported as follows: triclinic, P1, a = 8.644(3) ?, b = 9.840(3) ?, c = 20.162(6) ?, α = 97.355(5)°, β = 97.100(5)°, γ = 98.606(5)°, V = 1663.8(9) ?(3), Z = 4, and final R = 0.0319. The two Ni-N bonds to the central N donors of the terpy ligands in 1 average 1.990(2) ?, while the four peripheral Ni-N bonds average 2.107(10) ?. This difference in the M-N bond length for terpy complexes is typical of the complexes of smaller metal ions, while for larger metal ions, the difference is reversed. The significance of the metal-ion size dependence of the selectivity of polypyridyl ligands, and the greater rigidity of ligands based on aromatic groups such as pyridyl groups, is discussed.     

Novel square planar copper(II) complexes with imino or nitronyl nitroxide radicals exhibiting large ferro- and antiferromagnetic interactions

This paper reports the synthesis, crystal structures, and magnetic properties of two copper(II) complexes (1, 2) of general formula Cu(tfac)2(radical)2 (tfac = trifluoroacetate; radical = (1) 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (NITPh) or (2) 2-phenyl-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazoline-1- oxyl (IMPh)). They crystallize in the monoclinic P2(1)/n space group with the following parameters: (1) a = 13.212(2) A, b = 9.136(1) A, c = 15.587(2) A, beta = 114.61(1) degrees, Z = 2; (2) a = 11.059(2) A, b = 15.289(1) A, c = 10.694(2) A, beta = 114.20(1) degrees, Z = 2. In both complexes the copper(II) ion is coordinated to two radicals in a slightly distorted square planar surrounding. The copper(II)-radical exchange couplings are antiferromagnetic for the nitronyl nitroxide (NITPh) complex (1) and ferromagnetic in the case of the imino nitroxide (IMPh) analogue (2). The ground state has been found to be a spin-doublet for 1 and the spin-quartet for 2. No thermal population of the highest states has been observed, indicating copper(II)-radical couplings of magnitude of J > 500 cm-1.     

Single-molecule magnets: Jahn-Teller isomerism and the origin of two magnetization relaxation processes in Mn12 complexes

Several single-molecule magnets with the composition [Mn12O12(O2CR)16(H2O)x] (x = 3 or 4) exhibit two out-of-phase ac magnetic susceptibility signals, one in the 4-7 K region and the other in the 2-3 K region. New Mn12 complexes were prepared and structurally characterized, and the origin of the two magnetization relaxation processes was systematically examined. Different crystallographic forms of a Mn12 complex with a given R substituent exist where the two forms have different compositions of solvent molecules of crystallization and this results in two different arrangements of bound H2O and carboxylate ligands for the two crystallographically different forms with the same R substituent. The X-ray structure of cubic crystals of [Mn12O12(O2CEt)16(H2O)3]. 4H2O (space group P1) (complex 2a) has been reported previously. The more prevalent needle-form of [Mn12O12(O2CEt)16(H2O)3] (complex 2b) crystallizes in the monoclinic space group P2(1)/c, which at -170 degrees C has a = 16.462(7) A, b = 22.401(9) A, c = 20.766(9) A, beta = 103.85(2) degrees, and Z = 4. The arrangements of H2O and carboxylate ligands on the Mn12 molecule are different in the two crystal forms. The complex [Mn12O12-(O2)CC6H4-p-Cl)16(H2O)4].8CH2Cl2 (5) crystallizes in the monoclinic space group C2/c, which at -172 degrees C has a = 29.697(9) A, b = 17.708(4) A, c = 30.204(8) A, beta = 102.12(2) degrees, and Z = 4. The ac susceptibility data for complex 5 show that it has out-of-phase signals in both the 2-3 K and the 4-7 K ranges. X-ray structures are also reported for two isomeric forms of the p-methylbenzoate complex. [Mn12O12(O2CC6H4-p-Me)16(H2O)4]. (HO2CC6H4-p-Me) (6) crystallizes in the monoclinic space group C2/c, which at 193 K has a = 40.4589(5) A, b = 18.2288(2) A, c = 26.5882(4) A, beta = 125.8359(2) degrees, and Z = 4. [Mn12O12(O2CC6H4-p-Me)16(H2O)4].3(H2O) (7) crystallizes in the monoclinic space group I2/a, which at 223 K has a = 29.2794(4) A, b = 32.2371(4) A, c = 29.8738(6) A, beta = 99.2650(10) degrees, and Z = 8. The Mn12 molecules in complexes 6 and 7 differ in their arrangements of the four bound H2O ligands. Complex 6 exhibits an out-of-phase ac peak (chi(M)' ') in the 2-3 K region, whereas the hydrate complex 7 has a chi(M)' ' signal in the 4-7 K region. In addition, however, in complex 6, one Mn(III) ion has an abnormal Jahn-Teller distortion axis oriented at an oxide ion, and thus 6 and 7 are Jahn-Teller isomers. This reduces the symmetry of the core of complex 6 compared with complex 7. Thus, complex 6 likely has a larger tunneling matrix element and this explains why this complex shows a chi(M)' ' signal in the 2-3 K region, whereas complex 7 has its chi(M)' ' peak in the 4-7 K region, i.e., the rate of tunneling of magnetization is greater in complex 6 than complex 7. Detailed 1H NMR experiments (2-D COSY and TOCSY) lead to the assignment of all proton resonances for the benzoate and p-methyl-benzoate Mn12 complexes and confirm the structural integrity of the (Mn12O12) complexes upon dissolution. In solution there is rapid ligand exchange and no evidence for the different isomeric forms of Mn12 complexes seen in the solid state.     

Syntheses and Crystal Structures of Two New Zinc（ Ⅱ ） Nitroxide Radical Complexes Bridged by Isophthalate

Two novel complexes [Zn（NIT3-py）（ip）]n 1 and [Zn（im3-py）（ip）]n 2 （NIT3-py = 2-（3＇-pyridyl）-4,4,5,5,-tetramethylimidazoline-1-oxyl-3-oxide, im3-py = 2-（3＇-pyridyl）-4,4,5,5-tetramethylimidazoline-1-oxyl, ip = isophthalate） have been synthesized and structurally determined by X-ray diffraction. Crystal data for 1： C32H36N6O8Zn, Mr= 698.04, monoclinic, space group Cc with a = 23.600（3）, b = 10.2073（12）, c = 13.4027（16）A,β = 92.586（2）°, V = 3225.3（7） A^3, Dc= 1.438 g/cm^3, F（000） = 1456,μ（MoKa） = 0.822 mm^-1, Z = 4, the final R = 0.0390 and wR = 0.1032 for 6037 independent reflections with Rint = 0.0214. Crystal data for 2： C32H36N6O6Zn, Mr= 666.04, monoclinic, space group C2/c with a = 24.434（4）, b = 13.543（2）, c = 10.2379（16） A, β = 109.024（2）°, V = 3202.8（9）A3 Dc= 1.381 g/cm^3, F（000） = 1392,μ（MoKa） = 0.820 mm^-1, Z = 4, the final R = 0.0304 and wR = 0.0658 for 2833 independent reflections with Rint = 0.0307. X-ray analysis reveals that both Zn（ Ⅱ ） ions are four-coordinated by two pyridyl-N atoms from nitroxide radicals and two carboxylate oxygen atoms to form distorted tetrahedral geometries. Each isophthalate dianion binds two Zn（ Ⅱ ） ions in a monodentate mode, leading to a I-D chain structure.