Structural Diversity and Photoluminescent Properties of Two Mn(Ⅱ) Sulfoterephthalate Complexes from Multi-pyridine N-containing Ligands

Solvothermal reaction of manganese(II) salt with monosodium 2-sulfoterephthalate(2-NaH_2stp) and two multi-pyridine N-containing auxiliary ligands results in the formation of two new complexes formulated with [Mn_2(Hstp)_2(bpp)_2(H_2O)_4](1) and [Mn_3(stp)_2(tpy)_3(H_2O)](H_2O)_5(2)(bpp = benz-2,3-pyrimidine-[2,3-f]-1,10-phenanthroline, tpy = 2,2?:6?,2??-terpyridine). X-ray diffraction structural analyses of two complexes reveal their structural diversity(0D and 1D) due to the difference of auxiliary ligands. 1 is a discrete structure, in which the Mn(Ⅱ) ion is hexa-coordinated with one stp, one bpp ligand and two water molecules. Complex 2 is a one-dimensional(1D) chain-like structure with three crystallographically independent Mn(Ⅱ) ions. The photoluminescent properties could be assigned to the π-π* transition of 2-sulfoterephthalate ligands.     

Three New Zn(Ⅱ)/Cd(Ⅱ) Coordination Polymers Constructed with 2-Mercaptonicotinic Acid and 1,2-Di(4-pyridyl)ethylene: Syntheses and Structure Analysis

Three new Zn(Ⅱ)/Cd(Ⅱ) coordination polymers based on 2-mercaptonicotinic acid (H2mna) with 1,2-di(4-pyridyl)ethylene (dpe) introduced as a bridging ligand have been synthesized via hydrothermal method and structurally characterized by single-crystal X-ray diffraction as well as elemental analysis and IR. As reported in this paper, [Zn2(dpe)0.5(mna)2] (1) can be classified as a two-dimensional layer structure in which the 1D chain composed of Zn(Ⅱ) and mna ligands is bridged by dpe ligands, while the complex named [Zn4(dpe)4(mna)4] (2) is a tetra-nuclear cluster compound. These two compounds are further extended to three-dimensional structures by hydrogen bonds along with C-H…π and π…π interactions. Compound 3 with general formular [Cd2(dpe)0.5(mna)2]·H2O belongs to a three-dimensional porous structure in which the 2D metal layers formed by the coordination of Cd(Ⅱ) and mna ligands are connected with the bridging of dpe ligands.     

Hydrothermal Syntheses,Crystal Structures and Luminescence Properties of Cu(Ⅱ) and Cd(Ⅱ) Complexes Assembled by 6-Hydroxypicolinic Acid and 1,10-Phenanthroline

Two new complexes based on 6-hydroxypicolinic acid(H_2picO) and 1,10-phenanthroline(phen), such as [Cu_4(picO)_4(phen)_4]·12 H_2O(1) and {[Cd_4(picO)_4(phen)_4(H_2O)_2]·5H_2O}_n(2), have been synthesized and characterized by IR, elemental analyses, thermogravimetric analyses and X-ray diffraction technique. Single-crystal X-ray diffraction analyses revealed that the two complexes both crystallize in the triclinic system, space group P(16)-. For complex 1, the picO ligands adopt a tridentate coordination mode to link copper(Ⅱ) ions into dimmers. PicO ligands also adopt a tridentate mode in complex 2, which connects the cadmium(Ⅱ) to form a one-dimensional chain. Moreover, luminescent properties of 1 and 2 were also investigated.     

SYNTHESIS AND STRUCTURE OF TETRANUCLEAR MOLYBDENUM CLUSTER COMPOUND[Mo_4S_4(μ-O_2CC_6H_5)_2(dtp)_4]

The cluster compound[Mo_4S_4(μ-O_2CC_5H_5)_2(dtp)_4](dtp=S_2P(OEt)_2)wasobtained by the ligand substitution reaction of tetranuclear molybdenum cluster[Mo_4S_4(μ-dtp)_2(dtp)_4]in the mixed solvent of acetone,ethanol and water in thepresence of C_6H_5CO_2Na.It is monoclinic and crystallizes in space group C2/c,Mr=1495.09,a=12.175(5),b=22.01(1),c=20.875(9),β=99.04(4)°;V=5575(5);Z=4;Dc=1.78g/cm~3.Final R factor is 0.066.The result reveals that the[Mo_4S_4]clustercore and t-(dtp)~(-1)ligands are retained and only μ-bridged(dtp)~(-1)ligands aresubstituted by(C_6H_5CO_2)~(-1)in the substitution reaction,thus producing the newtitle cluster compound,the structure of which contains two species of bidentateligand.     

A New Cd(Ⅱ) Coordination Polymer Constructed by 3-(2-Pyridyl)pyrazole and 5-Nitroisophthalic Acid:Synthesis,Crystal Structure and Theoretical Calculations

A new coordination polymer, [Cd_2(NIPH)(L)_2(H_2O)]n(1, HL = 3-(2-pyridyl)pyrazole and H_2NIPH = 5-nitroisophthalic acid), has been synthesized. The structure of complex 1 has been characterized by X-ray single-crystal diffraction, elemental analysis, IR spectrum analysis, thermogravimetric analysis and fluorescence spectrum analysis. Complex 1 belongs to the triclinic system, space group P1 with a = 8.9539(6), b = 11.6252(8), c = 12.2472(8) ?, α = 80.011(2), β = 80.3850(10), γ = 86.773(2)°, V = 1237.37(14) ?~3, Z = 2, D_c = 1.987 g/cm~3, μ = 1.780 mm~(-1), M_r = 740.25, F(000) = 724, the final R = 0.0295 and wR = 0.1015 with I 2σ(I). Two H_2NIPH as monodentate and bidentate ligands and two L ligands link four Cd(Ⅱ) ions to form a tetranuclear subunit. Each pair of the tetranuclear subunits is bridged by NIPH ligands to yield a one-dimensional double-chain structure. Furthermore, the 1D chains are linked into a 3D supramolecular framework with hydrogen bonds and π-π interactions. In addition, we analyzed Natural Bond Orbital(NBO) in using the PBE0/LANL2DZ method built in Gaussian 03 Program. The calculation results indicated the obvious covalent interaction between the coordinated atoms and Cd(Ⅱ) ion.     

Layered and three-dimensional uranyl–organic assemblies with 4,4′-oxidiphthalic acid

Hydrothermal reactions of uranyl nitrate and 4,4'-oxidiphthalic acid(H_4L) resulted in the formation of three new uranyl-organic framework materials,namely(NH_4)_2[(UO_2)_3(L)_2]·5H_2O(1),(NEt_4)[(UO_2)_3(H_2O)(L)(HL)](2) and(UO_2)_7(H_2O)_2(phen)_4(L)_2(HL)_2(3)(NEt_4 = tetraethylammonium,phen = 1,10-phenanthroline).These three structures all comprise common uranyl pentagonal bipyramids.In 1,UO_7polyhedra are linked by hexadentate ligands to form a 3D framework with 1D channels,in which are located NH_4~+ ions and water molecules.While in 2,the organic ligands adopt pentadentate and hexadentate coordination modes,ligating UO_7 units to create a layered structure with channels filled by NEt_4~+ ions.For 3,uranyl square bipyramids are also accommodated together with pentagonal bipyramids,which are linked by tetradentate carboxylate ligands to produce the layered assembly.Phen molecules also coordinate to the uranyl centers to build up the structure.Luminescent studies indicate that 2 and 3 exhibit the characteristic uranyl emission.     

Syntheses,Crystal Structures and Magnetic Properties of Two New Low-dimensional Manganese (Ⅱ) Coordination Compounds

Two new low-dimensional Mn(Ⅱ) coordination compounds of Mn(H_2pimdc)_2(phen)(compound 1) and [Mn(Hpimdc)(phen)]n·nH_2O(compound 2) were synthesized, where H_3pimdc is a 2-propyl-imidazole-4,5-dicarboxylic acid and phen is 1,10-phenanthroline. Both compounds were thoroughly analyzed by X-ray single-crystal diffraction, element analysis, IR spectra, PXRD and thermal analysis. X-ray single-crystal diffraction analyses indicate that the phen ligands terminate metal ions on two sides to prevent the linkage between the neighboring metal ions into a higher dimensional structure in compounds 1 and 2. Compound 1 is constructed from mononuclear molecules which form the 1D helical supramolecular chain by N–H···O hydrogen bonds. In compound 2, Hpimdc is a tetradentate bridging ligand, which binds Mn(Ⅱ) ions to generate a single-stranded right helical chain parallel to the b axis. These 1D chains are additionally coupled by H-bonds as well as π···π stacking interactions, which formed a 3D supramolecular structure. Additionally, compound 2 demonstrated temperature-dependent magnetic susceptibility and negative value of θ(equal to –9.09 K), which is indicative of weak antiferromagnetic interactions between Mn(Ⅱ) ions.     

Syntheses and Crystal Structures of Two Copper~Ⅱ Complexes with Tetracyanonickelate~Ⅱ

Two copper-nickel complexes, {[Cu(i-Pr3TACN)][Ni(CN)4]}2·2H2O (1) and {[Cu(DACH)][Ni(CN)4]}n (2), have been synthesized by the self-assembly reactions of K2[Ni(CN)4] with CuCl2 and the corresponding chelating ligand 1,4,7-triisopropyl-1,4,7- triazacyclononane (i-Pr3TACN) or 1,4-diazacycloheptane (DACH), respectively. The complexes were structurally characterized by single-crystal X-ray diffraction, elemental analyses, IR spectra and magnetic properties. Complex 1 presents a [2+2] type of molecular square structure and 2 features a 2D β-pucker structure. The magnetic susceptibility measurements reveal a weak antiferromagnetic interaction between the Cu(Ⅱ) ions, with the J values of-22.11 and -32.50 cm-1 for 1 and 2. Moreover, by changing the size of macrocyclic ligands we have successfully constructed two different strictures, which may provide useful information for the construction of the structure.     

A Novel Three-dimensional Mn(Ⅱ) Coordination Polymer Constructed from Biphenyl-3,3?,5,5?-tetracarboxylic Acid and Water

The title Mn(Ⅱ) coordination polymer,poly{[heptaaqua-(μ4-bi-phenyl-3,3?,5,5?-tetracarboxylate)-bimanganese(Ⅱ)] pentahydrate},[Mn_2(bpta)(H_2O)_7]_n·5n H_2O(I),is crystallized from a mixture of biphenyl-3,3?,5,5?-tetracarboxylic acid(H_4bpta) and MnCl_2·4H_2O in waterethanol under room temperature. Its asymmetric unit consists of one and two halves of crystallographically independent Mn(Ⅱ) cations,one fully deprotonated H4 bpta ligand,seven coordinated water molecules and five solvent water as guest molecules. In I,each Mn(Ⅱ) atom is octahedrally coordinated by six oxygen atoms from bpta~(4-) anions and coordinated water molecules. In the Mn(Ⅱ) cations,one half Mn(Ⅱ) ion of them located at a 2-fold axis generating a trinuclear [Mn_3(H_2O)_2(RCOO)_2] linker by μ1,1-O(water) and μ1,3-O,O?(carboxylate) bridges and another half Mn(Ⅱ) ion with an inversion is a mononuclear linker. These neighbouring trinuclear and mononuclear Mn(Ⅱ) cations are linked together by biphenyl-3,3?,5,5?-tetracarboxylates to form a three-dimensional framework with a(42.84) topology of a(4,4)-connected net,in which the positions of the trinuclear [Mn_3(H_2O)_2(R-COO)_2] linker as a 4-connector linking four bpta~(4-) ligands in I reproduce an eagle-shaped arrangement. The polymeric structure exhibits a water channel with an accessible void of 797.1 ?~3,amounting to 15.7% of the total unit-cell volume. Each of the cavities in the network is occupied by solvent water molecules.     

Novel Lanthanide Cluster Polymers Based on Cubane-like [Ln_4(OH)_4]~(8+) Clusters and Sulfate Anions

Two lanthanide-oxo-cluster polymers were synthesized by hydrothermal reaction using Ln_2O_3 as initial lanthanide materials:[Ln_4(SO_4)_4(OH)_4(H_2O)_7]·_4H_2O(Ln = Er 1,Ho 2),and characterized by PXRD,IR spectra,X-ray single-crystal diffraction,2D IR correlation spectra and UV-visible absorption spectra.Single-crystal X-ray analyses reveal that compounds 1 and 2 are isostructural,and they are both crystallized in the orthorhombic system Pccn space group.Compound 1 is a 3D lanthanide cluster polymer based on tetranuclear cubane-like [Er_4(μ_3-OH)_4]~(8+) cations and SO_4~(2-) anions.The overall structure of 1 can be assigned to 6-connected pcu-type topology with the point symbol of(4~(12).6~3).     

Four New Cu（Ⅱ） Complexes with Benzotriazole-based Ligands： Syntheses,Crystal Structures and Theoretical Investigations

Four new Cu（Ⅱ） complexes with two benzotriazole-based ligands, [Cu2（L^1）2（NO3）2]· 2H2O （1）, [Cu2（L^1）2]·2ClO4·2H2O （2）, [Cu2（HL^2）2（NO3）4]·2CH3COCH3 （3） and [Cu（HL^2）2（Cl）]·Cl·2CH2Cl2 （4）, where HL^1 = 1,3-bis（benzotriazol-2-yl）-2-propanol and HL^2 = 1,3-bis（benzotriazol-1-yl）-2-propanol, were synthesized and structurally characterized by elemental analyses, IR and single-crystal X-ray diffraction analyses. It is revealed that complexes 1～3 have dinuclear structures, while 4 possesses a one-dimensional （1-D） chain structure, which extends in two orthogonal orientations. In 1～4, the coordination numbers of Cu（Ⅱ） centers range from four to six, which may be attributed to the different geometries and coordination abilities of the ligands and anions. The L^1 ligand in complexes 1 and 2 adopts a tridentate di-chelating coordination mode, whereas ligand HL^2 in complexes 3 and 4 has a bidentate bridging coordination mode. The different coordination modes of these two ligands may be explained by the different charges of nitrogen donor atoms in the benzotriazole ring, which has been investigated by density functional theory （DFT） calculations.     

Syntheses and Crystal Structures of Two New Metal Phosphonates:[Mn(H_2O)_2(C_(12)H_8N_2)(HO_3PCH_2CH_2CO_2)] and [Co(H_2O)_4(C_(10)H_8N_2)]·(HO_3PCH_2CH_2CO_2)

By the reactions of manganese(II) acetate, 2-sulfoethylphosphonic acid, 1,10-phen (1,10-phen = 1, 10-phenanthroline) or cobalt(II) acetate, 4,4'-bipy and 2-carboxyethylphosphonic acid, two novel compounds of [Mn(H2O)2(C12H8N2)(HO3PCH2CH2CO2)] (1) and[Co(H2O)4 (C10H8N2)]· (HO3PCH2CH2CO2) (2) have been synthesized and characterized by IR spectroscopy, elemental analyses and single-crystal X-ray diffraction. Compound 1 has a 0D structure. Two Mn(II) ions are linked by two 2-carboxyethylphosphonic acid ligands, forming a centrosymmetric dimer. These dimers are further interlinked into a 2D layer structure by π-π stacking interactions and hydrogen bonds. Compound 2 has a 1D chain structure. The 2-carbo- xyethylphosphonic acid remains uncoor- dinated and acts as the organic template. By the bridge of 4,4'-bipy, the [Co(4,4'-bipy)]2+ chains are formed.     

Synthesis,Crystal Structure and Physical Properties of a Novel Cadmium(Ⅱ) Supramolecular 3D Framework

A new inorganic-organic hybrid cadmium(Ⅱ) complex [Cd2(H1/2C4BIm)2(CH3COO)]nhas been prepared by a hydrothermal reaction,and characterized by fluorescence,IR,TGA,and single-crystal X-ray diffraction analysis.In its crystal structure,there are two kinds of coordinating forms for those Cd(Ⅱ) ions.One is that the Cd(Ⅱ) ion is coordinated by one carboxylate oxygen atom from one acetate oxygen ligand and three benzimidazole nitrogen atoms from three 2,2’-(1,4-butanediyl)bis(1H-benzimidazole)(H2C4BIm) ligands,and the other is that the Cd(Ⅱ) ion is coordinated by four benzimidazole nitrogen atoms from four H2C4 BIm ligands to furnish two distorted tetrahedral coordination geometries.It exhibits a beautiful structure for a 2D layer and a 3D network,with its four-connecting nodes provided by the H2C4 BIm ligands.Furthermore,this complex shows intense luminescent property at room temperature.In [Cd2(H2C2BIm)2(C9H6O4)2]n,the H2C2 BIm ligand lost the role as a bridging ligand because of the shorter alkyl chain compared with that of H2C4 BIm ligand.     

Two Coordination Polymers Constructed by Cd(Ⅱ) and Zn(Ⅱ) with in situ Generated 5-(3-Pyridyl)tetrazolate Ligand:Syntheses,Crystal Structures and Luminescence Properties

Hydrothermal reactions of 3-cyanopyridine and Na N3 with Zn Cl_2 or Cd Cl_2·5/2H_2 O in the presence of 1,4-benzenedicarboxylic acid(H2bdc) yielded two new coordination polymers,{[Zn(3-ptz)(bdc)_(0.5)(H_2O)_2]n·2H_2O}_n(1) and [Cd_2(3-ptz)_2Cl_2]_n(2),based on in situ synthesized 5-(3-pyridyl)tetrazolate(3-ptz-) organic ligand.They have been structurally characterized by elemental analysis(EA),infrared spectroscopy(IR) and single-crystal/powder X-ray diffraction(PXRD).In 1,two Zn(Ⅱ) ions are linked together through two μ_2-(3-ptz-) ligands to form a dimeric unit of [Zn(μ_2-3-ptz)(H_2O)_2]_2~(2+),which is further connected with other equivalent units by μ_2-bdc~(2-)spacers,resulting in an infinite 1D polymeric chain of [Zn_2(3-ptz)_2(H_2O)_2(bdc)]_n,and then strong hydrogen bonding interactions extend these 1D chains into a 3D supramolecular structure.In 2,the Cd(Ⅱ) ions are connected through μ_4-(3-ptz-) ligands and Cl-anions,leading to infinite 2D layers of [Cd_2(3-ptz)Cl_2]_n~(n+),which are further linked by another μ_4-(3-ptz-) pillared ligand to form a 3D layered-pillared framework architecture of [Cd)2(3-ptz))2Cl)2])n.Furthermore,thermal stability of these compounds was measured by thermogravimetric analysis(TGA) and their photoluminescent properties were also investigated in the solid state at room temperature.     

Synthesis and Structural Characterization of Mono- and Di-nuclear Zinc(Ⅱ) Coordination Compounds of Triphenylphosphoniopropionate

Two novel coordination compounds of Zn(Ⅱ) with Ph3P (CH2)2CO-2(L), namely, [ZnL4(H2O)2]·(ClO4)2·2H2O(compound 1) and [Zn2Cl4(μ-L-O,O′)2](compound 2), have been prepared. The single crystal X-ray structure analysis of these compounds indicates that in compound 1 the Zn(Ⅱ) atom is coordinated by four monodentate carboxylato groups on the equatorial plane and two aqua ligands occupy the axial coordination positions. The pendant oxygen atoms form strong hydrogen bonds with the aqua molecules which results in the stability of this structure. In compound 2, two Zn(Ⅱ) atoms are bridged by a pair of carboxylato groups, showing a skew-bridge mode, and thus enabling a long Zn(Ⅱ)…Zn(Ⅱ) separation. As we know, it is a dinuclear coordination compound with the longest Zn…Zn separation.     

Four Complexes of Mn(Ⅱ), Co(Ⅱ), Ni(Ⅱ) and Cu(Ⅱ) Based on 2-Morpholine-4-yl-4,6-di-pyrazol-1-yl-1,3,5-triazine

Three azide bridged complexes, namely, [Mn_2L_2(N_3)_4(H_2O)_2](1), [Co_2L_2(N_3)_4]·(H_2O)_3(2) and [Ni_2L_2(N_3)_3(H_2O)]N_3·(H_2O)_4(3)(L = 2-morpholine-4-yl-4,6-di-pyrazol-1-yl-1,3,5-triazine), were synthesized by the reaction of L ligand, sodium azide with Mn(Ⅱ), Co(Ⅱ) and Ni(Ⅱ) chlorides. The copper(Ⅱ) chloride combined with thiocyanate and L ligand to form a mononuclear complex [CuL(CH_3OH)(SCN)(NCS)](4). Complexes 1~4 were characterized by IR, elemental analysis and X-ray crystallographic analysis. It was worth noting that two Mn(Ⅱ) atoms were connected by the end-to-end mode in 1, while Co(Ⅱ) and Ni(Ⅱ) atoms were connected by the end-on mode in 2 and 3. In complex 4, the central copper atom was coordinated with a sulfur atom and a nitrogen atom of the two thiocyanate ligands, respectively. Hydrogen bonds, π-π stacking interactions, thermogravimetric analysis and fluorescence properties of 1~4 were studied.     

Crystal Engineering of Co(Ⅱ) Metal-organic Frameworks Based on the Hydrolysis Product of Letrozole and Coligands

The cyanide groups of letrozole(1-[bis(4-cyanophenyl)methyl]-1,2,4-triazole) were hydrolyzed into the carboxylic groups under alkaline conditions. Then the hydrolysis product(1-[bis(4-carboxylphenyl)methyl]-1,2,4-triazole, H_2ltzda) reacted with Co(NO_3)_2·6H_2O in the presence of different bipyridl-typed ligands under hydrothermal conditions. As a result, two new Co(Ⅱ) MOFs were obtained, formulated as [Co_2(ltzda)_2(bpp)_2]_n(1) and {[Co_2(ltzda)_2(bpy)]·4H_2O}_n(2)(bpp = 1,3-di(4-pyridyl)propane, bpy = 4,4'-bipyridine). Two MOFs have been characterized by single-crystal X-ray diffraction, thermogravimetric analysis and magnetic measure. 1 displays a 2D metal-organic framework containing wave layers and 2 shows a pillared-layer structure existing in a 2-fold interpenetrated mode.     

Syntheses and Crystal Structures of Two New Metal Phosphonates： [Mn（H2O）2（C12H8N2） （HO3PCH2CH2CO2） ] and [Co（H2O）4（C10H8N2）]-（HOaPCH2CH2CO2）

By the reactions of manganese（if） acetate, 2-sulfoethylphosphonic acid, 1,10-phen （1,10-phen = 1, 10-phenanthroline） or cobalt（Ⅱ） acetate, 4,4＇-bipy and 2-carboxyethylphosphonic acid, two novel compounds of [Mn（H2O）2（C12H8N2） （HO3PCH2CH2CO2） ] （1） and[Co（H2O）4（C10H8N2）]-（HOaPCH2CH2CO2） （2） have been synthesized and characterized by IR spectroscopy, elemental analyses and single-crystal X-ray diffraction. Compound 1 has a 0D structure. Two Mn（ii） ions are linked by two 2-carboxyethylphosphonic acid ligands, forming a centrosymmetric dimer. These dimers are further interlinked into a 2D layer structure by π-π stacking interactions and hydrogen bonds. Compound 2 has a 1D chain structure. The 2-carboxyethylphosphonic acid remains uncoordinated and acts as the organic template. By the bridge of 4,4＇-bipy, the [Co（4,4＇-bipy）]^2＋ chains are formed.     

Cu(Ⅰ) and Cu (Ⅱ) helical complexes formed with oligobipyridine ligand

A new asymmetric oligobipyridine ligand, 1-(5'-methyl-2, 2'-bipyridin-5-yl)-2-(6'-methyl-2, 2'-bipyridin-6-yl)ethane (L), in which the bipyridine units are bridged by CH_2CH_2 at 5, 6'-position has been synthesized. The ligand L reacts with Cu(Ⅰ) and Cu(Ⅱ) ions giving double-stranded helical complexes [Cu_2~ⅠL_2] (ClO_4)_2·Et_2O (1) and [Cu_2~ⅡL_2 (OH) (H_2O)][ClO_4]_3(2), respectively. Complexes 1 and 2 were characterized by X-ray diffraction analyses, ES-MS, ESR and cyclic voltammetry, etc. Differing from the oligobipyridine ligands bridged by CH_2CH_2 at 6,6'-or 5,5'-position, the ligand L not only forms a double-stranded helicate with Cu(Ⅰ) ion, but also gives a double-stranded helicate with Cu(Ⅱ) ion. The results show that the linkage mode of the spacer group to the bipyridine units exerts a great impact on the formation of helix.     

Synthesis,structures and magnetic properties of a series of polynuclear copper(Ⅱ)-lanthanide(Ⅲ) complexes assembled with carboxylate and hydroxide ligands

Heterometallic copper(Ⅱ)-lanthanide(Ⅲ) complexes have been made with a variety of exclusively O-donor ligands including betaines (zwitterionic carboxylates) and chloroac-etate,which are dinuclear CuLn,tetranuclear Cu2Ln2,pen-tanuclear Cu2Ln2,and octadecanuclear Cu12Ln6 complexes.Hie results show that subtle changes in both the carboxylates and acidity of the reaction solution can cause drastic changes in the structures of the products.Magnetic studies exhibit that shielding of the Ln3 4f electrons by the outer shell electrons is very effective to preclude significant coupling interaction between the Ln3 4f electrons and Cu2 3d electrons in either a mono-atomic hydroxide-bridged,or a carboxylate-bridged system.