Synthesis and characterization of mixed-valent manganese phosphonate cage complexes

The reaction of phenylphosphonic acid (PhPO(3)H(2)) with the mixed-valent basic oxo-centered manganese triangle [Mn(3)O(O(2)CCMe(3))(6)(py)(3)] (1; where py=pyridine) in the presence of a suitable base gives four different manganese clusters depending on the identity of the base. The syntheses and structural characterization of [Mn(18)(mu(3)-O)(8)(PhPO(3))(14)(O(2)CCMe(3))(12)(py)(6)(H(2)O)(2)] (2), [Mn(7)(mu(3)-O)(3)(O(3)PPh)(3)(O(2)CCMe(3))(8)(py)(3)] (3), [Mn(9)Na(mu(3)-O)(4)(mu(4)-O)(2)(O(3)PPh)(2)(O(2)CCMe(3))(12)(H(2)O)(2)(H(2)O)(0.67)(Py)(0.33)] (4), and [Mn(13)(mu(3)-O)(8)(OMe)(8)(O(3)PPh)(4)(O(2)CCMe(3))(10)] (5) are described. Complexes 4 and 5 are homovalent Mn(III) cages, while 2 and 3 contain divalent, trivalent, and/or tetravalent ions. All the manganese centers are valence-localized, the octahedral Mn(III) sites being recognizable by marked Jahn-Teller distortions. The magnetic properties of compounds 2-5 have been investigated in the polycrystalline state by magnetic susceptibility and high-field magnetization measurements, which reveal that spin ground states vary from 0< or =S > or =8. AC susceptibility measurements performed on 4 and 5, in the 1.6-10.0 K ranges show the presence of out of AC susceptibility signal (chi(M)') for 4, and an effective energy barrier (U(eff)) for the re-orientation of the magnetization is found to be 17 K, but for 5, the chi(M)' maximum is found to be below 1.5 K.     

Synthesis, structure, and catalytic properties of V(IV), Mn(III), Mo(VI), and U(VI) complexes containing bidentate (N, O) oxazine and oxazoline ligands

Synthesis of seven complexes containing oxazoline ([(L(1))(2)V=O] (4), [(L(1))(2)MoO(2)] (5), [(L(1))(2)UO(2)] (6); HL(1) (1) [HL(1) = 2-(4',4'-dimethyl-3'-4'-dihydroxazol-2'-yl)phenol]), chiral oxazoline ([(L(2))(2)UO(2)] (7); HL(2) (2) [HL(2) = (4'R)-2-(4'-ethyl-3'4'-dihyroxazol-2'-yl)phenol]), and oxazine ([(L(3))(2)V=O] (8), [(L(3))(2)Mn(CH(3)COO(-))] (9), [(L(3))(2)Co] (10); HL(3) (3) [HL(3) = 2-(5,6-dihydro-4H-1,3-oxazolinyl)phenol]) and their characterization by various techniques such as UV-vis, IR, and EPR spectroscopy, mass spectrometry, cyclic voltammetry, and elemental analysis are reported. The novel oxazine (3) and complexes 4, 5, 8 and 9 were also characterized by X-ray crystallography. Oxazine 3 crystallizes in the monoclinic system with the P2(1)/n space group, complexes 4 and 9 crystallize in the monoclinic system with the P2(1)/c space group, and complexes 5 and 8 crystallize in the orthorhombic system with the C222(1) space group and the P2(1)2(1)2(1) chiral space group, respectively. The representative synthetic procedure involves the reaction of metal acetate or acetylacetonate derivatives with corresponding ligand in ethanol. Addition of Mn(OAc)(2).4H(2)O to an ethanol solution of 3 gave the unexpected complex Mn(L(3))(2).(CH(3)COO(-)) (9) where the acetate group is coordinated with the metal center in a bidentate fashion. The catalytic activity of complexes 4-9 for oxidation of styrene with tert-butyl hydroperoxide was tested. In all cases, benzaldehyde formed exclusively as the oxidation product.     

Metal-induced cyclization of thiosemicarbazones derived from beta-keto amides and beta-keto esters: open-chain and cyclized ligands in zinc(II) complexes

The reactions of Zn(OAc)(2) with acetoacetanilide, methyl acetoacetate, o-acetoacetanisidide, and ethyl 2-methylacetoacetate thiosemicarbazones (HTSC(1), HTSC(2), HTSC(3), and HTSC(4), respectively) were explored in methanol. With HTSC(1), HTSC(2), and HTSC(3), following isolation of the corresponding zinc(II) thiosemicarbazonates [Zn(TSC(x))(2)] (x = 1, 2, 3), the mother liquors afforded pyrazolonate complexes [ZnL(1)(2)(H(2)O)] (HL(1) = 2,5-dihydro-3-methyl-5-oxo-1H-pyrazole-1-carbothioamide) that had been formed by cyclization of the corresponding TSC(-). The reaction of HTSC(4) with zinc(II) acetate gave only the pyrazolonate complex [ZnL(2)(2)(H(2)O)] (HL(2) = 2,5-dihydro-3,4-dimethyl-5-oxo-1H-pyrazole-1-carbothioamide). All compounds were studied by IR and NMR spectroscopy, and HTSC(3), [Zn(TSC(3))(2)] x DMSO, [ZnL(1)(2)(H(2)O)] x 2DMSO, and [ZnL(2)(2)(H(2)O)] x 2DMSO were also studied by X-ray diffractometry, giving a thorough picture of the cyclization process. In preliminary tests of the effects of HL(1) and [ZnL(1)(2)(H(2)O)] on rat paw inflammatory edema induced by carrageenan, HL(1) showed antiinflammatory activity.     

Phosphato, chromato, and perrhenato complexes of titanium(IV) and zirconium(IV) containing Kläui's tripodal ligand

Treatment of titanyl sulfate in dilute sulfuric acid with 1 equiv of NaL(OEt) (L(OEt)(-) = [(eta(5)-C(5)H(5))Co{P(O)(OEt)(2)](3)](-)) in the presence of Na(3)PO(4) and Na(4)P(2)O(7) led to isolation of [(L(OEt)Ti)(3)(mu-O)(3)(mu(3-)PO(4))] (1) and [(L(OEt)Ti)(2)(mu-O)(mu-P(2)O(7))] (2), respectively. The structure of 1 consists of a Ti(3)O(3) core capped by a mu(3)-phosphato group. In 2, the [P(2)O(7)](4-) ligands binds to the two Ti's in a mu:eta(2),eta(2) fashion. Treatment of titanyl sulfate in dilute sulfuric acid with NaL(OEt) and 1.5 equiv of Na(2)Cr(2)O(7) gave [(L(OEt)Ti)(2)(mu-CrO(4))(3)] (3) that contains two L(OEt)Ti(3+) fragments bridged by three mu-CrO(4)(2-)-O,O' ligands. Complex 3 can act as a 6-electron oxidant and oxidize benzyl alcohol to give ca. 3 equiv of benzaldehyde. Treatment of [L(OEt)Ti(OTf)(3)] (OTf(-) = triflate) with [n-Bu(4)N][ReO(4)] afforded [[L(OEt)Ti(ReO(4))(2)](2)(mu-O)] (4). Treatment of [L(OEt)MF(3)] (M = Ti and Zr) with 3 equiv of [ReO(3)(OSiMe(3))] afforded [L(OEt)Ti(ReO(4))(3)] (5) and [L(OEt)Zr(ReO(4))(3)(H(2)O)] (6), respectively. Treatment of [L(OEt)MF(3)] with 2 equiv of [ReO(3)(OSiMe(3))] afforded [L(OEt)Ti(ReO(4))(2)F] (7) and [[L(OEt)Zr(ReO(4))(2)](2)(mu-F)(2)] (8), respectively, which reacted with Me(3)SiOTf to give [L(OEt)M(ReO(4))(2)(OTf)] (M = Ti (9), Zr (10)). Hydrolysis of [L(OEt)Zr(OTf)(3)] (11) with Na(2)WO(4).xH(2)O and wet CH(2)Cl(2) afforded the hydroxo-bridged complexes [[L(OEt)Zr(H(2)O)](3)(mu-OH)(3)(mu(3)-O)][OTf](4) (12) and [[L(OEt)Zr(H(2)O)(2)](2)(mu-OH)(2)][OTf](4) (13), respectively. The solid-state structures of 1-3, 6, and 11-13 have been established by X-ray crystallography. The L(OEt)Ti(IV) complexes can catalyze oxidation of methyl p-tolyl sulfide with tert-butyl hydroperoxide. The bimetallic Ti/ Re complexes 5 and 9 were found to be more active catalysts for the sulfide oxidation than other Ti(IV) complexes presumably because Re alkylperoxo species are involved as the reactive intermediates.     

New family of silver(I) complexes based on hydroxyl and carboxyl groups decorated arenesulfonic acid: syntheses, structures, and luminescent properties

Self-assembly of silver(I) salts and three ortho-hydroxyl and carboxyl groups decorated arenesulfonic acids affords the formation of nine silver(I)-sulfonates, (NH(4))·[Ag(HL1)(NH(3))(H(2)O)] (1), {(NH(4))·[Ag(3)(HL1)(2)(NH(3))(H(2)O)]}(n) (2), [Ag(2)(HL1)(H(2)O)(2)](n) (3), [Ag(2)(HL2)(NH(3))(2)]·H(2)O (4), [Ag(H(2)L2)(H(2)O)](n) (5), [Ag(2)(HL2)](n) (6), [Ag(3)(L3)(NH(3))(3)](n) (7), [Ag(2)(HL3)](n) (8), and [Ag(6)(L3)(2)(H(2)O)(3)](n) (9) (H(3)L1 = 2-hydroxyl-3-carboxyl-5-bromobenzenesulfonic acid, H(3)L2 = 2-hydroxyl-4-carboxylbenzenesulfonic acid, H(3)L3 = 2-hydroxyl-5-carboxylbenzenesulfonic acid), which are characterized by elemental analysis, IR, TGA, PL, and single-crystal X-ray diffraction. Complex 1 is 3-D supramolecular network extended by [Ag(HL1)(NH(3))(H(2)O)](-) anions and NH(4)(+) cations. Complex 2 exhibits 3-D host-guest framework which encapsulates ammonium cations as guests. Complex 3 presents 2-D layer structure constructed from 1-D tape of sulfonate-bridged Ag1 dimers linked by [(Ag2)(2)(COO)(2)] binuclear units. Complex 4 exhibits 3-D hydrogen-bonding host-guest network which encapsulates water molecules as guests. Complex 5 shows 3-D hybrid framework constructed from organic linker bridged 1-D Ag-O-S chains while complex 6 is 3-D pillared layered framework with the inorganic substructure constructing from the Ag2 polyhedral chains interlinked by Ag1 dimers and sulfonate tetrahedra. The hybrid 3-D framework of complex 7 is formed by L3(-) trianions bridging short trisilver(I) sticks and silver(I) chains. Complex 8 also presents 3-D pillared layered framework, and the inorganic layer substructure is formed by the sulfonate tetrahedrons bridging [(Ag1O(4))(2)(Ag2O(5))(2)](∞) motifs. Complex 9 represents the first silver-based metal-polyhedral framework containing four kinds of coordination spheres with low coordination numbers. The structural diversities and evolutions can be attributed to the synthetic methods, different ligands and coordination modes of the three functional groups, that is, sulfonate, hydroxyl and carboxyl groups. The luminescent properties of the nine complexes have also been investigated at room temperature, especially, complex 1 presents excellent blue luminescence and can sensitize Tb(III) ion to exhibit characteristic green emission.     

Syntheses, Structures, and Steady State and Time Resolved Photophysical Properties of a Tetraiminodiphenol Macrocyclic Ligand and Its Dinuclear Zinc(II)/Cadmium(II) Complexes with Coordinating and Noncoordinating Anions

The work in the present investigation reports the syntheses, structures, steady state, and time-resolved photophysical properties of a tetraiminodiphenol macrocyclic ligand H(2)L and its eight dinuclear zinc(II) complexes and one cadmium(II) complex having composition [Zn(2)L(H(2)O)(2)](ClO(4))(2)·2CH(3)CN (1), [Zn(2)L(H(2)O)(2)](ClO(4))(2)·2dmf (2), [Zn(2)L(H(2)O)(2)](NO(3))(2)·2dmf (3), [Zn(2)LCl(2)] (4), [Zn(2)L(N(3))(2)] (5), [Zn(2)L(NCS)(2)] (6), [Zn(2)L(NCO)(2)] (7), [Zn(2)L(NCSe)(2)](2)·dmf (8), and [Cd(2)L(OAc)(2)] (9) with various coordinating and noncoordinating anions. The structures of all the complexes 1-9 have been determined by single-crystal X-ray diffraction. The noncovalent interactions in the complexes result in the generation of the following topologies: two-dimensional network in 1, 2, 4, 6, 7, 8, and 9; three-dimensional network in 5. Spectrophotometric and spectrofluorometric titrations of the diprotonated salt [H(4)L](ClO(4))(2) with triethylamine as well as with zinc(II) acetate and cadmium(II) acetate have been carried out, revealing fluorescence enhancement of the macrocyclic system by the base and the metal ions. Steady state fluorescence properties of [H(4)L](ClO(4))(2) and 1-9 have been studied and their quantum yields have been determined. Time resolved fluorescence behavior of [H(4)L](ClO(4))(2) and the dizinc(II) and dicadmium(II) complexes 1-9 have also been studied, and their lifetimes and radiative and nonradiative rate constants have been determined. The induced fluorescence enhancement of the macrocycle by zinc(II) and cadmium(II) is in line with the greater rate of increase of the radiative rate constants in comparison to the smaller rate of increase of nonradiative rate constants for the metal complexes. The fluorescence decay profiles of all the systems, being investigated here, that is, [H(4)L](ClO(4))(2) and 1-9, follow triexponential patterns, revealing that at least three conformers/components are responsible to exhibit the fluorescence decay behavior. The systems and studies in this report have been compared with those in the reports of the previously published similar systems, revealing some interesting aspects.     

Effect of cyanato, azido, carboxylato, and carbonato ligands on the formation of cobalt(II) polyoxometalates: characterization, magnetic, and electrochemical studies of multinuclear cobalt clusters

Five Co(II) silicotungstate complexes are reported. The centrosymmetric heptanuclear compound K(20)[{(B-beta-SiW(9)O(33)(OH))(beta-SiW(8)O(29)(OH)(2))Co(3)(H(2)O)}(2)Co(H(2)O)(2)]47 H(2)O (1) consists of two {(B-beta-SiW(9)O(33)(OH))(beta-SiW(8)O(29)(OH)(2))Co(3)(H(2)O)} units connected by a {CoO(4)(H(2)O)(2)} group. In the chiral species K(7)[Co(1.5)(H(2)O)(7))][(gamma-SiW(10)O(36))(beta-SiW(8)O(30)(OH))Co(4)(OH)(H(2)O)(7)]36 H(2)O (2), a {gamma-SiW(10)O(36)} and a {beta-SiW(8)O(30)(OH)} unit enclose a mononuclear {CoO(4)(H(2)O)(2)} group and a {Co(3)O(7)(OH)(H(2)O)(5)} fragment. The two trinuclear Co(II) clusters present in 1 enclose a mu(4)-O atom, while in 2 a mu(3)-OH bridging group connects the three paramagnetic centers of the trinuclear unit, inducing significantly larger Co-L-Co (L=mu(4)-O (1), mu(3)-OH (2)) bridging angles in 2 (theta(av(Co-L-Co))=99.1 degrees ) than in 1 (theta(av(Co-L-Co))=92.8 degrees ). Weaker ferromagnetic interactions were found in 2 than in 1, in agreement with larger Co-L-Co angles in 2. The electrochemistry of 1 was studied in detail. The two chemically reversible redox couples observed in the positive potential domain were attributed to the redox processes of Co(II) centers, and indicated that two types of Co(II) centers in the structure were oxidized in separate waves. Redox activity of the seventh Co(II) center was not detected. Preliminary experiments indicated that 1 catalyzes the reduction of nitrite and NO. Remarkably, a reversible interaction exists with NO or related species. The hybrid tetranuclear complexes K(5)Na(3)[(A-alpha-SiW(9)O(34))Co(4)(OH)(3)(CH(3)COO)(3)]18 H(2)O (3) and K(5)Na(3)[(A-alpha-SiW(9)O(34))Co(4)(OH)(N(3))(2)(CH(3)COO)(3)]18 H(2)O (4) were characterized: in both, a tetrahedral {Co(4)(L(1))(L(2))(2)(CH(3)COO)(3)} (3: L(1)=L(2)=OH; 4: L(1)=OH, L(2)=N(3)) unit capped the [A-alpha-SiW(9)O(34)](10-) trivacant polyanion. The octanuclear complex K(8)Na(8)[(A-alpha-SiW(9)O(34))(2)Co(8)(OH)(6)(H(2)O)(2)(CO(3))(3)]52 H(2)O (5), containing two {Co(4)O(9)(OH)(3)(H(2)O)} units, was also obtained. Compounds 2, 3, 4, and 5 were less stable than 1, but their partial electrochemical characterization was possible; the electronic effect expected for 3 and 4 was observed.     

Complexes of copper(II) with 3-(ortho-substituted phenylhydrazo)pentane-2,4-diones: syntheses, properties and catalytic activity for cyclohexane oxidation

Reactions of copper(II) with 3-phenylhydrazopentane-2,4-diones X-2-C(6)H(4)-NHN=C{C(=O)CH(3)}(2) bearing a substituent in the ortho-position [X = OH (H(2)L(1)) 1, AsO(3)H(2) (H(3)L(2)) 2, Cl (HL(3)) 3, SO(3)H (H(2)L(4)) 4, COOCH(3) (HL(5)) 5, COOH (H(2)L(6)) 6, NO(2) (HL(7)) 7 or H (HL(8)) 8] lead to a variety of complexes including the monomeric [CuL(4)(H(2)O)(2)]·H(2)O 10, [CuL(4)(H(2)O)(2)] 11 and [Cu(HL(4))(2)(H(2)O)(4)] 12, the dimeric [Cu(2)(H(2)O)(2)(μ-HL(2))(2)] 9 and the polymeric [Cu(μ-L(6))](n)] 13 ones, often bearing two fused six-membered metallacycles. Complexes 10-12 can interconvert, depending on pH and temperature, whereas the Cu(II) reactions with 4 in the presence of cyanoguanidine or imidazole (im) afford the monomeric compound [Cu(H(2)O)(4){NCNC(NH(2))(2)}(2)](HL(4))(2)·6H(2)O 14 and the heteroligand polymer [Cu(μ-L(4))(im)](n)15, respectively. The compounds were characterized by single crystal X-ray diffraction (complexes), electrochemical and thermogravimetric studies, as well as elemental analysis, IR, (1)H and (13)C NMR spectroscopies (diones) and ESI-MS. The effects of the substituents in 1-8 on the HOMO-LUMO gap and the relative stability of the model compounds [Cu(OH)(L(8))(H(2)O)]·H(2)O, [Cu(L(1))(H(2)O)(2)]·H(2)O and [Cu(L(4))(H(2)O)(2)]·H(2)O are discussed on the basis of DFT calculations that show the stabilization follows the order: two fused 6-membered > two fused 6-membered/5-membered > one 6-membered metallacycles. Complexes 9, 10, 12 and 13 act as catalyst precursors for the peroxidative oxidation (with H(2)O(2)) of cyclohexane to cyclohexanol and cyclohexanone, in MeCN/H(2)O (total yields of ca. 20% with TONs up to 566), under mild conditions.     

Dodecanuclear manganese(III) phosphonates with cage structures

Treatments of Mn(O(2)CR)(2) (R = Me, Ph) with NBu(4)MnO(4) in CH(3)CN or CH(3)CN/CH(2)Cl(2) in the presence of acetic acid, delta(1)-cyclohexenephosphonic acid (C(6)H(9)PO(3)H(2)), and 2,2'-bipyridine or 1,10-phenanthroline result in three novel dodecamanganese(III) clusters [Mn(12)O(8)(O(2)CMe)(6)(O(3)PC(6)H(9))(7)(bipy)(3)] (1), [Mn(12)O(8)(O(2)CPh)(6)(O(3)PC(6)H(9))(7)(bipy)(3)] (2), and [Mn(12)O(8)(O(2)CPh)(6)(O(3)PC(6)H(9))(7)(phen)(3)] (3). They have a similar Mn(12) core of [Mn(III)(12)(mu(4)-O)(3)(mu(3)-O)(5)(mu-O(3)P)(3)] with a new type of topologic structure. Solid-state dc magnetic susceptibility measurements of complexes 1-3 reveal that dominant antiferromagnetic interactions are propagated between the magnetic centers. The ac magnetic measurements suggest an S = 2 ground state for compounds 1 and 3 and an S = 3 ground state for compound 2.     

Aqueous reactions of U(VI) at high chloride concentrations: syntheses and structures of new uranyl chloride polymers

The reactions of UO(3) with acidic aqueous chloride solutions resulted in the formation of two new polymeric U(VI) compounds. Single crystals of Cs(2)[(UO(2))(3)Cl(2)(IO(3))(OH)O(2)].2H(2)O (1) were formed under hydrothermal conditions with HIO(3) and CsCl, and Li(H(2)O)(2)[(UO(2))(2)Cl(3)(O)(H(2)O)] (2) was obtained from acidic LiCl solutions under ambient temperature and pressure. Both compounds contain pentagonal bipyramidal coordination of the uranyl dication, UO(2)(2+). The structure of 1 consists of infinite [(UO(2))(3)Cl(2)(IO(3))(mu(3)-OH)(mu(3)-O)(2)](2-) ribbons that run down the b axis that are formed from edge-sharing pentagonal bipyramidal [UO(6)Cl] and [UO(5)Cl(2)] units. The Cs(+) cations separate the chains from one another and form long ionic contacts with terminal oxygen atoms from iodate ligands, uranyl oxygen atoms, water molecules, and chloride anions. In 2, edge-sharing [UO(3)Cl(4)] and [UO(5)Cl(2)] units build up tetranuclear [(UO(2))(4)(mu-Cl)(6)(mu(3)-O)(2)(H(2)O)(2)](2-) anions that are bridged by chloride to form one-dimensional chains. These chains are connected in a complex network of hydrogen bonds and interactions of uranyl oxygen atoms with Li(+) cations. Crystal data: 1, orthorhombic, space group Pnma, a = 8.2762(4) A, b = 12.4809(6) A, c = 17.1297(8) A, Z = 4; 2, triclinic, space group P1, a = 8.110(1) A, b = 8.621(1) A, c = 8.740(1) A, Z = 2.     

Synthesis, structures, and magnetic properties of the copper(II), cobalt(II), and manganese(II) complexes with 9-acridinecarboxylate and 4-quinolinecarboxylate ligands

To explore the relationships between the structures of ligands and their complexes, we have synthesized and characterized a series of metal complexes with two structurally related ligands, 9-acridinecarboxylic acid (HL(1)) and 4-quinolinecarboxylate acid (HL(2)), [Cu(2)(mu(2)-OMe)(2)(L(1))(2)(H(2)O)(0.69)](n) 1, [Cu(2)(L(1))(4)(CH(3)OH)(2)] 2, [Cu(3)(L(1))(6)(CH(3)OH)(6)].3H(2)O 3, [Mn(3)(L(1))(6)(CH(3)OH)(6)].3H(2)O 4, [Co(3)(L(1))(6)(CH(3)OH)(6)].3H(2)O 5, [Cu(L(2))(2)](n) 6, [Mn(L(2))(2)(H(2)O)](n) 7, and [Co(L(2))(2)(H(2)O)](n) 8. 1 is a three-dimensional (3D) polymer with an interpenetrating NbO type network showing one-dimensional (1D) channels, whereas 2 and 3 take bi- and trinuclear structures, respectively, because of the differences in basicity of the reaction systems in preparing the three complexes. 4 and 5 have trinuclear structures similar to that of 3. In 1-5, ligand L(1) performs different coordination modes with N,O-bridging in 1 and O,O'-bridging in 2-5, and the metal ions also show different coordination geometries: square planar in 1, square pyramidal in 2, and octahedral in 3-5. 6 has a two-dimensional structure containing (4,4) grids in which L(2) adopts the N,O-bridging mode and the Cu(II) center takes square planar geometry. 7 and 8 are isostructural complexes showing 1D chain structures, with L(2) adopting the O,O-bridging mode. In addition, the intermolecular O-H...N hydrogen bonds and pi-pi stacking interactions further extend the complexes (except 1 and 6), forming 3D structures. The magnetic properties of 2-7 have been investigated and discussed in detail.     

A family of 13 tetranuclear zinc(II)-lanthanide(III) complexes of a [3+3] Schiff-base macrocycle derived from 1,4-diformyl-2,3-dihydroxybenzene

A family of thirteen tetranuclear heterometallic zinc(II)-lanthanide(III) complexes of the hexa-imine macrocycle (L(Pr))(6-), with general formula Zn(II)(3)Ln(III)(L(Pr))(NO(3))(3)·xsolvents (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm or Yb), were prepared in a one-pot synthesis using a 3:1:3:3 reaction of zinc(II) acetate, the appropriate lanthanide(III) nitrate, the dialdehyde 1,4-diformyl-2,3-dihydroxybenzene (H(2)L(1)) and 1,3-diaminopropane. A hexanuclear homometallic zinc(II) macrocyclic complex [Zn(6)(L(Pr))(OAc)(5)(OH)(H(2)O)]·3H(2)O was obtained using a 2:0:1:1 ratio of the same reagents. A control experiment using a 1:0:1:1 ratio failed to generate the lanthanide-free [Zn(3)(L(Pr))] macrocyclic complex. The reaction of H(2)L(1) and zinc(II) acetate in a 1:1 ratio yielded the pentanuclear homometallic complex of the dialdehyde H(2)L(1), [Zn(5)(L(1))(5)(H(2)O)(6)]·3H(2)O. An X-ray crystal structure determination revealed [Zn(3)(II)Pr(III)(L(Pr))(NO(3))(2)(DMF)(3)](NO(3))·0.9DMF has the large ten-coordinate lanthanide(III) ion bound in the central O(6) site with two bidentate nitrate anions completing the O(10) coordination sphere. The three square pyramidal zinc(II) ions are in the outer N(2)O(2) sites with a fifth donor from DMF. Measurement of the magnetic properties of [Zn(II)(3)Dy(III)(L(Pr))(NO(3))(3)(MeOH)(3)]·4H(2)O with a weak external dc field showed that it has a frequency-dependent out-of-phase component of ac susceptibility, indicative of slow relaxation of the magnetization (SMM behaviour). Likewise, the Er and Yb analogues are field-induced SMMs; the latter is only the second example of a Yb-based SMM. The neodymium, ytterbium and erbium complexes are luminescent in the solid phase, but only the ytterbium and neodymium complexes show strong lanthanide-centred luminescence in DMF solution.     

Family of carboxylate- and nitrate-diphenoxo triply bridged dinuclear Ni(II)Ln(III) complexes (Ln = Eu, Gd, Tb, Ho, Er, Y): synthesis, experimental and theoretical magneto-structural studies, and single-molecule magnet behavior

Seven acetate-diphenoxo triply bridged M(II)-Ln(III) complexes (M(II) = Ni(II) and Ln(III) = Gd, Tb, Ho, Er, and Y; M(II) = Zn(II) and Ln(III) = Ho(III) and Er(III)) of formula [M(μ-L)(μ-OAc)Ln(NO(3))(2)], one nitrate-diphenoxo triply bridged Ni(II)-Tb(III) complex, [Ni(μ-L)(μ-NO(3))Tb(NO(3))(2)]·2CH(3)OH, and two diphenoxo doubly bridged Ni(II)-Ln(III) complexes (Ln(III) = Eu, Gd) of formula [Ni(H(2)O)(μ-L)Ln(NO(3))(3)]·2CH(3)OH have been prepared in one pot reaction from the compartmental ligand N,N',N"-trimethyl-N,N"-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine (H(2)L). Moreover, Ni(II)-Ln(III) complexes bearing benzoate or 9-anthracenecarboxylate bridging groups of formula [Ni(μ-L)(μ-BzO)Dy(NO(3))(2)] and [Ni(μ-L)(μ-9-An)Dy(9-An)(NO(3))(2)]·3CH(3)CN have also been successfully synthesized. In acetate-diphenoxo triply bridged complexes, the acetate bridging group forces the structure to be folded with an average hinge angle in the M(μ-O(2))Ln bridging fragment of ~22°, whereas nitrate-diphenoxo doubly bridged complexes and diphenoxo-doubly bridged complexes exhibit more planar structures with hinge angles of ~13° and ~2°, respectively. All Ni(II)-Ln(III) complexes exhibit ferromagnetic interactions between Ni(II) and Ln(III) ions and, in the case of the Gd(III) complexes, the J(NiGd) coupling increases weakly but significantly with the planarity of the M-(O)(2)-Gd bridging fragment and with the increase of the Ni-O-Gd angle. Density functional theory (DFT) theoretical calculations on the Ni(II)Gd(III) complexes and model compounds support these magneto-structural correlations as well as the experimental J(NiGd) values, which were found to be ~1.38 and ~2.1 cm(-1) for the folded [Ni(μ-L)(μ-OAc)Gd(NO(3))(2)] and planar [Ni(H(2)O)(μ-L)Gd(NO(3))(3)]·2CH(3)OH complexes, respectively. The Ni(II)Dy(III) complexes exhibit slow relaxation of the magnetization with Δ/k(B) energy barriers under 1000 Oe applied magnetic fields of 9.2 and 10.1 K for [Ni(μ-L)(μ-BzO)Dy(NO(3))(2)] and [Ni(μ-L)(μ-9-An)Dy(9-An)(NO(3))(2)]·3CH(3)CN, respectively.     

Substitution and derivatization reactions of a water soluble iron(II) complex containing a self-assembled tetradentate phosphine ligand

Facile substitution reactions of the two water ligands in the hydrophilic tetradentate phosphine complex cis-[Fe{(HOCH2)P{CH2N(CH2P(CH2OH)2)CH2}2P(CH2OH)}(H2O)2](SO4) (abbreviated to [Fe(L1)(H2O)2](SO4), 1) take place upon addition of Cl-, NCS-, N3(-), CO3(2-) and CO to give [Fe(L1)X2] (2, X = Cl; 4, X = NCS; 5, X=N3), [Fe(L1)(kappa2-O(2)CO)], 6 and [Fe(L1)(CO)2](SO4), 7. The unsymmetrical mono-substituted intermediates [Fe(L1)(H2O)(CO)](SO(4)) and [Fe(L(1))(CO)(kappa(1)-OSO(3))] (8/9) have been identified spectroscopically en-route to 7. Treatment of 1 with acetic anhydride affords the acylated derivative [Fe{(AcOCH2)P{CH2N(CH2P(CH2OAc)2)CH2}2P(CH2OAc)}(kappa2-O(2)SO2)] (abbreviated to [Fe(L2)(kappa2-O(2)SO2)], 10), which has increased solubility over 1 in both organic solvents and water. Treatment of 1 with glycine does not lead to functionalisation of L1, but substitution of the aqua ligands occurs to form [Fe(L(1))(NH(2)CH(2)CO(2)-kappa(2)N,O)](HSO(4)), 11. Compound 10 reacts with chloride to form [Fe(L(2))Cl(2)] 12, and 12 reacts with CO in the presence of NaBPh4 to form [Fe(L2)Cl(CO)](BPh4) 13b. Both of the chlorides in 12 are substituted on reaction with NCS- and N3(-) to form [Fe(L2)(NCS)2] 14 and [Fe(L2)(N3)2] 15, respectively. Complexes 2.H2O, 4.2H2O, 5.0.812H2O, 6.1.7H2O, 7.H2O, 10.1.3CH3C(O)CH3, 12 and 15.0.5H2O have all been crystallographically characterised.     

Zinc(II) ortho-hydroxyphenylhydrazo-β-diketonate complexes and their catalytic ability towards diastereoselective nitroaldol (Henry) reaction

The zinc(II) complexes with ortho-hydroxy substituted arylhydrazo-β-diketonates [Zn(2)(CH(3)OH)(2)(μ-L(1))(2)] (5), [Zn{(CH(3))(2)SO}(H(2)O)(L(2))] (6), [Zn(2)(H(2)O)(2)(μ-L(3))(2)] (7) and [Zn(H(2)O)(2)(L(4))]·H(2)O (8) were synthesized by reaction of a zinc(II) salt with the appropriate hydrazo-β-diketone, HO-2-C(6)H(4)-NHN=C{C(=O)CH(3)}(2) (H(2)L(1), 1), HO-2-O(2)N-4-C(6)H(3)-NHN=C{C(=O)CH(3)}(2) (H(2)L(2), 2), HO-2-C(6)H(4)-NHN=CC(=O)CH(2)C(CH(3))(2)CH(2)C(=O) (H(2)L(3), 3) or HO-2-O(2)N-4-C(6)H(3)-NHN=[CC(=O)CH(2)C(CH(3))(2)CH(2)C(=O) (H(2)L(4), 4). They were fully characterized, namely by X-ray diffraction analysis that disclosed the formation of extensive H-bonds leading to 1D chains (5 and 6), 2D layers (7) or 3D networks (8). The thermodynamic parameters of the Zn(II) reaction with H(2)L(2) in solution, as well as of the thermal decomposition of 1-8 were determined. Complexes 5-8 act as diastereoselective catalysts for the nitroaldol (Henry) reaction. The threo/erythro diastereoselectivity of the β-nitroalkanol products ranges from 8:1 to 1:10 with typical yields of 80-99%, depending on the catalyst and substrate used.     

Step-wise synthesis of inorganic-organic hybrid based on γ-octamolybdate-based tectons

With the bottom-up design principle, we use metal-ions to bridge the predesigned tectons (1 [(H(2)L(1))(2)(Mo(8)O(26))]·4H(2)O and 3 [(H(2)L(2))(L(2))(0.5)(Mo(8)O(26))(0.5)]·H(2)O) so that two higher dimensional γ-octamolybdate based inorganic-organic hybrid compounds 2 [Cu(I)(2)(L(1))(3)(Mo(8)O(26))(0.5)] and 4 [Ni(L(2))(2)(HL(2))(2)(Mo(8)O(26))]·4H(2)O are successfully obtained.     

Rational assembly of soluble copper(II) phosphonates: synthesis, structure and magnetism of molecular tetranuclear copper(II) phosphonates

The reactions of the dinuclear copper complexes [Cu(2)(L)(OAc)] [H(3)L = N,N'-(2-hydroxypropane-1,3-diyl)bis(salicylaldimine) or [Cu(2)(L')(OAc)] (H(3)L' = N,N'-(2-hydroxypropane-1,3-diyl)bis(4,5-dimethylsalicylaldimine)] with various phosphonic acids, RPO(3)H(2) (R = t-Bu, Ph, c-C(5)H(9), c-C(6)H(11) or 2,4,6-i-Pr(3)-C(6)H(2)), leads to the replacement of the acetate bridge affording tetranuclear copper(II) phosphonates, [Cu(4)(L)(2)(t-BuPO(3))](CH(3)OH)(2)(C(6)H(6)) (1), [Cu(4)(L)(2)(PhPO(3))(H(2)O)(2)(NMe(2)CHO)](H(2)O)(2) (2), [Cu(4)(L')(2)(C(5)H(9)PO(3))](CH(3)OH)(2) (3), [Cu(4)(L')(2)(C(6)H(11)PO(3)](MeOH)(4)(H(2)O)(2) (4) and [Cu(4)(L')(2)(C(30)H(46)P(2)O(5))](PhCH(3)) (5). The molecular structures of 1-4 reveal that a [RPO(3)](2-) ligand is involved in holding the four copper atoms together by a 4.211 coordination mode. In 5, an in situ formed [(RPO(2))(2)O](4-) ligand bridges two pairs of the dinuclear subunits. Magnetic studies on these complexes reveal that the phosphonate ligand is an effective conduit for magnetic interaction among the four copper centers present; a predominantly antiferromagnetic interaction is observed at low temperatures.     

Coordination chemistry of conformation-flexible 1,2,3,4,5,6-cyclohexanehexacarboxylate: trapping various conformations in metal-organic frameworks

To study the conformations of 1,2,3,4,5,6-cyclohexanehexacarboxylic acid (H(6)L), eleven new coordination polymers have been isolated from hydrothermal reactions of different metal salts with 1e,2a,3e,4a,5e,6a-cyclohexanehexacarboxylic acid (3e+3a, H(6)L(I)) and characterized. They are [Cd(12)(mu(6)-L(II))(mu(10)-L(II))(3)(mu-H(2)O)(6)(H(2)O)(6)]16.5 H(2)O (1), Na(12)[Cd(6)(mu(6)-L(II))(mu(6)-L(III))(3)]27 H(2)O (2), [Cd(3)(mu(13)-L(II))(mu-H(2)O)] (3), [Cd(3)(mu(6)-L(III))(2,2'-bpy)(3)(H(2)O)(3)]2 H(2)O (4), [Cd(4)(mu(4)-L(VI))(2)(4,4'-Hbpy)(4)(4,4'-bpy)(2)(H(2)O)(4)]9.5 H(2)O (5), [Cd(2)(mu(6)-L(II))(4,4'-Hbpy)(2)(H(2)O)(10)]5 H(2)O (6), [Cd(3)(mu(11)-L(VI))(H(2)O)(3)] (7), [M(3)(mu(9)-L(II))(H(2)O)(6)] (M=Mn (8), Fe (9), and Ni (10)), and [Ni(4)(OH)(2)(mu(10)-L(II))(4,4'-bpy)(H(2)O)(4)]6 H(2)O (11). Three new conformations of 1,2,3,4,5,6-cyclohexanehexacarboxylate, 6e (L(II)), 4e+2a (L(III)) and 5e+1a (L(VI)), have been derived from the conformational conversions of L(I) and trapped in these complexes by controlling the conditions of the hydrothermal systems. Complexes 1 and 2 have three-dimensional (3D) coordination frameworks with nanoscale cages and are obtained at relatively low temperatures. A quarter of the L(I) ligands undergo a conformational transformation into L(II) while the others are transformed into L(III) in the presence of NaOH in 2, while all of the L(I) are transformed into L(II) in the absence of NaOH in 1. Complex 3 has a 3D condensed coordination framework, which was obtained under similar reaction conditions as 1, but at a higher temperature. The addition of 2,2'-bipyridine (2,2'-bpy) or 4,4'-bipyridine (4,4'-bpy) to the hydrothermal system as an auxiliary ligand also induces the conformational transformation of H(6)L(I). A new L(VI) conformation has been trapped in complexes 4-7 under different conditions. Complex 4 has a 3D microporous supramolecular network constructed from a 2D L(III)-bridged coordination layer structure by pi-pi interactions between the chelating 2,2'-bpy ligands. Complexes 5-7 have different frameworks with L(II)/L(VI) conformations, which were prepared by using different amounts of 4,4'-bpy under similar synthetic conditions. Both 5 and 7 are 3D coordination frameworks involving the L(VI) ligands, while 6 has a 3D microporous supramolecular network constructed from a 2D L(II)-bridged coordination layer structure by interlayer N(4,4'-Hbpy)--HO(L(II)) hydrogen bonds. 3D coordination frameworks 8-11 have been obtained from the H(6)L(I) ligand and the paramagnetic metal ions Mn(II), Fe(II), and Ni(II), and their magnetic properties have been studied. Of particular interest to us is that two copper coordination polymers of the formulae [{Cu(II) (2)(mu(4)-L(II))(H(2)O)(4)}{Cu(I) (2)(4,4'-bpy)(2)}] (12 alpha) and [Cu(II)(Hbtc)(4,4'-bpy)(H(2)O)]3 H(2)O (H(3)btc=1,3,5-benzenetricarboxylic acid) (12 beta) resulted from the same one-pot hydrothermal reaction of Cu(NO(3))(2), H(6)L(I), 4,4'-bpy, and NaOH. The Hbtc(2-) ligand in 12 beta was formed by the in situ decarboxylation of H(6)L(I). The observed decarboxylation of the H(6)L(I) ligand to H(3)btc may serve as a helpful indicator in studying the conformational transformation mechanism between H(6)L(I) and L(II-VI). Trapping various conformations in metal-organic structures may be helpful for the stabilization and separation of various conformations of the H(6)L ligand.     

Amphiphilic and magnetic properties of a new class of cluster-bearing [L2Cu4(mu4-O)(mu2-carboxylato)4] soft materials

A general approach toward amphiphilic systems bearing multimetallic clusters and their ability to form Langmuir-Blodgett films is presented. The synthetic strategy to stabilize these clusters involves the use of a ligand (HL) containing an N(2)O-donor set and long octadecanoic chains to obtain the carboxylate-supported [L(2)Cu(4)(mu(4)-O)(mu(2)-OAc)(4)]EtOH (1) and [L(2)Cu(4)(mu(4)-O)(mu(2)-OBz)(4)] (2) in which OAc(-) and OBz(-) represent acetate (1) and benzoate (2) co-ligands. These species were thoroughly characterized and had their structures solved by X-ray crystallography. We observed that the mu-oxo Cu(4) cluster is antiferromagnetically coupled and used broken-symmetry density functional theory (DFT) calculations to describe the main superexchange pathways of the tetracopper core. We also describe the amphiphilic properties of the ligand and the cluster-containing systems by means of area versus pressure isotherms and show that these cluster-bearing species can be transferred onto solid substrates yielding homogeneous Langmuir-Blodgett films, as characterized by atomic force microscopy and contact angle measurements.     

Synthesis and characterization of novel oxo-centered phosphanylzincates of potassium and cesium with a central Zn6O2P4 double-heterocubane cage

The hydrolysis reaction of K(2)(MeZn)(2)(PSitBu(3))(2) in THF/toluene solution yields the [(MeZn)(4)Zn(2)(mu(3)-PSitBu(3))(4)(mu(4)-O)(2)](4-) anions independent of the applied stoichiometry. If the applied molar ratio resembles the composition of the anion, [(thf)K](2)[(eta(6)-toluene)K](2)[(MeZn)(4)Zn(2)(mu(3)-PSitBu(3))(4)(mu(4)-O)(2)] (1) crystallizes from a mixture of THF and toluene. In the case with less water, a phosphanediylzincate moiety is bonded to this anion, and [Zn(PSitBu(3))(2)K(4)(thf)(6)](2)[(MeZn)(4)Zn(2)(mu(3)-PSitBu(3))(4)(mu(4)-O)(2)] (2) crystallizes. However, again the major product is 1. The same anion is also observed with larger and softer cations, and [(thf)(3)Cs(2)](2)[(MeZn)(4)Zn(2)(mu(3)-PSitBu(3))(4)(mu(4)-O)(2)] (3) is obtained if the cesium zincate is used in this reaction. In all of these compounds, the anion is a slightly distorted Zn(6)O(2)P(4) double-heterocubane cage with a central Zn(2)O(2) ring having Zn-O bond lengths of approximately 207 pm.