Copper(II) oxalate and oxamate complexes

Reaction of Cu^II salts with phenanthroline and oxalate (ox) or oxamate (oxm) gives [Cu(phen)(ox)(H₂O)] · H₂O or [Cu(phen)(oxm)(H₂O)] · H₂O complexes while direct treatment of Cu^II salts with oxalate or oxamate gives [NH₄]₂[Cu(ox)₂] and [Cu(oxm)₂(H₂O)₂] respectively. The X-ray structures of one example of each system, aquo-oxamato-phenanthroline-copper(II)-dihydrate and the polymeric ammonium-bis(aquo)-tetraoxalato-dicopper(II)-dihydrate, are reported.     

Syntheses,crystal structures and electrochemistry of divalent metal 4-methylbenzenesulfonate complexes with o-phenanthroline

Three new compounds, namely [Mn(phen)₂(L)₂] · EtOH (1), [Zn(phen)₂(H₂O)₂]2L · 6H₂O (2) and [Cd(phen)₂(H₂O)₂]2L · 6H₂O (3), where HL = 4-methylbenzenesulfonic acid and phen = o-phenanthroline, have been synthesized, and their crystal structures determined by X-ray diffraction. In the complexes the metal atoms have two different coordination environments. Complex (1) consists of neutral molecules, [Mn(phen)₂(L)₂], in which Mn^II is six-coordinated by four nitrogen atoms from two o-phenanthroline molecules and two oxygen atoms from two sulfonate ions. Complexes (2) and (3) are isomorphous, each consisting of cationic species [M(phen)₂(H₂O)₂]²⁺ [M = Zn (2), Cd (3)], in which M^II is six-coordinated by four nitrogen atoms from two o-phenanthroline molecules and two water molecules. The electrochemical behavior and FT-IR of these compounds were also studied in detail.     

Tetrathiomolybdates of nickel

Summary The complexes [Ni(en)₃]MoS₄, [Ni(dien)₂]MoS₄ and [Ni(phen)₂(MoS₄)]·2H₂O (en = ethylenediamine, dien = diethylenetriamine, phen = 1,10-phenanthroline) were prepared. On the basis of their magnetochemical and spectral properties the compounds can be characterized as octahedral nickel(II) complexes. The complexes were also studied by c.v. Chemical oxidation of [Ni(en)₃]MoS₄ affords [Ni(en)MoS₄]₂SO₄; this complex has been characterized by i.r. and e.p.r. spectroscopy and by magnetic measurements.     

Cobalt(II), nickel(II) and copper(II) complexes withN-cyano-N′-methyl-N″(2-[(5-methyl-1H-imidazol-4-yl)methylthio]ethyl)guanidine

Summary N-Cyano-N-methyl-N(2-[(5-methyl-1H-imidazol-4-yl)-methylthio] ethyl) guanidine cimetidine (CM), complexes with Co^II, Ni^II and Cu^II are described. The compounds are of stoichiometry [M(CM)₂]SO₄ · nH₂O [M = Co^II, Ni^II or Cu^II; n = 3,3 or 4, respectively], [M(CM)₂](ClO₄)₂ [M = Co^II or Ni^II], [M(CM)₂]Cl₂ · nH₂O [M=Co^II, Ni^II or Cu^II; n = 1, 2, or 2, respectively] and [Cu(CM)SO₄] · 2H₂O. The electronic spectra of the compounds in solid state, magnetic susceptibilities and i.r. and e.p.r. spectra were studied. Octahedral environments are proposed for the complexes: [M(CM)₂]SO₄·nH₂O, [M(CM)₂](ClO₄)₂, [Ni(CM)₂]Cl₂ · 2H₂O, [Cu(CM)₂]Cl₂ · 2H₂O and [Cu(CM)SO₄] · 2H₂O and a tetrahedral structure for [Co(CM)₂]Cl₂ · H₂O.     

Comprehensive studies on the DNA-binding and cleavage properties of a nickel complex derived from phthalate and 1,10-phenanthroline

Binding properties of a nickel complex, [Ni(phen)(pha)(H₂O)₃] (phen = 1,10-phenanthroline, pha = o-phthalate) to DNA were comprehensively investigated by electronic absorption spectroscopy, viscosity, electrochemistry, melting temperature and gel electrophoresis measurements. After interaction with DNA, the hypochromism and bathochromism for the characteristic absorption peaks of [Ni(phen)(pha)(H₂O)₃] revealed a typical intercalation, which was proved by viscosity and melting temperature experiments. Electrochemical assays showed that the electrochemical activity of the nickel complex was shielded after inserting into the double-helix structure of DNA. Moreover, the results of agarose gel electrophoresis showed that the complex had moderate cleavage ability to supercoiled DNA in the presence of H₂O₂.     

Thermal studies of 2-methyl-1, 2-propanediamine complexes of nickel(II) in the solid state

Summary The complexes, [NiL₂]Br₂ (L=2-methyl-1, 2-propanediamine), [NiL₂(H₂O)₂]SeO₄·2H₂O, [NiL₂]X₂·2H₂O (X=0.5SO₄ or 0.5SeO₄) and [NiL₂(NCS)₂] have been prepared and investigated thermally. Upon heating, [NiL₂]Br₂ exhibits reversible thermochromism from yellow to blue: [NiL₂]X₂·2H₂O (X=0.5SO₄ or 0.5SeO₄) undergoes dehydration accompanied with irreversible thermochromism from yellow to blue yielding [NiL₂X₂], whereas [NiL₂(H₂O)₂]SeO₄·2H₂O (blue) transforms irreversibly into [NiL₂SeO₄] (blue). [NiL₂]X₂ (X=0.5SO₄ or 0.5SeO₄), prepared from their corresponding diaquo complexes by the temperature arrest technique, shows irreversible thermochromism from yellow to blue without showing any peak in the d.t.a./d.s.c. curves. [NiL₂(NCS)₂] (blue) undergoes a thermally induced phase transition without any visual change. All the yellow species are square planar; the blue species are octahedral. These colour changes are due to configurational changes; the phase change in [NiL₂(NCS)₂] is probably due to conformational changes in the diamine chelate rings.     

Selective anion-exchange intercalation of isomeric benzoate anions into the layered double hydroxide [LiAl2(OH)6]Cl·H2O

All the geometric isomers of the benzoate derivatives, XC₆H₄CO₂⁻ (X=F, Cl, Br, OH, OCH₃, NO₂, CO₂CH₃, NH₂, N(CH₃)₂) can be intercalated into the layered double hydroxide [LiAl₂(OH)₆]Cl·H₂O in 50% (v/v) water/ethanol solution at 80 °C to give fully anion-exchanged first stage intercalation compounds [LiAl₂(OH)₆]G·yH₂O (G=a substituted benzoate). The observed interlayer separations of the intercalates vary from 14.3 Å for [LiAl₂(OH)₆](4-nitrobenzoate)·2H₂O to 20.6 Å for [LiAl₂(OH)₆](3-dimethylaminobenzoate)·3H₂O. Competitive intercalation studies using mixtures of isomeric benzoates showed that the 4-isomers and 2-isomers are the most and the least preferred anions, respectively. Comparing the calculated dipole moments of the anions with the observed isomeric intercalation preferences suggests that dipole moment may be a good general index for the preference; however, it should be remembered that the bulkiness and electronegativity of the other substituent could be very important factors that affect the preferential intercalation.     

Synthesis,spectral and EPR studies of oxovanadium(IV) complexes incorporating tridentate ONO donor hydrazone ligands: Structural study of one oxovanadium(V) complex

Five oxovanadium(IV) complexes of 2-hydroxy-4-methoxybenzaldehyde nicotinic acid hydrazone (H₂L¹), 2-hydroxy-4-methoxyacetophenone nicotinic acid hydrazone (H₂L²) and a binuclear oxovanadium(V) complex of H₂L² have been synthesized. These complexes were characterized by different physicochemical techniques like electronic, infrared and EPR spectral studies. The complexes [VOL¹]₂ · H₂O (1) and [VOL²]₂ · H₂O (4) are binuclear and [VOL¹bipy] (2), [VOL¹phen] · 1.5H₂O (3) and [VOL²phen] · 2H₂O (6) are heterocyclic base adducts and are EPR active. In frozen DMF at 77 K, all the oxovanadium(IV) complexes show axial anisotropy with two sets of eight line patterns. The complex [VOL² · OCH₃]₂ (5) is an unusual product and has distorted octahedral geometry, as obtained by X-ray diffraction studies.     

Synthesis and Properties of Acidic 3d-Metal Urates

Acidic urates [Mn(HL)₂] · H₂O, [FeOH(HL)₂]₂ · 4H₂O, [Co(HL)₂(H₂O)₂] · 2H₂O, and [Ni(HL)₂(H₂O)₂] · 2H₂O (H₂L is uric acid) were synthesized and their structures and physicochemical properties were studied using IR spectroscopy, diffuse reflection spectroscopy, DTA, and magnetochemistry methods. The metals were shown to coordinate the urate anion through oxygen and nitrogen atoms. The [FeOH(HL)₂]₂ · 4H₂O complex has a dimeric structure.     

Assembling of copper(II) dipicolinate complexes

The role of ancillary ligands, namely imidazole (im), pyridine (py), 2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen) in the assembly of copper(II) dipicolinate complexes are presented. Mononuclear complexes are observed in the case of monodentate ligands. The mononuclear complex [Cu(im)₃L]·4H₂O (1) (L = dipicolinate anion) has a distorted octahedral structure with Z′ = 2, whereas [CuL(py)(H₂O)]·2H₂O (2) adopts distorted square pyramidal geometry. The bidentate ligands bpy and phen favor the formation of dinuclear complexes. The dinuclear complex [CuL(bpy)(μ-L)Cu(bpy)(H₂O)]·9H₂O (3) has one carbonyl oxygen atom of a carboxylate group of dipicolinate acting as a bridging ligand to the copper site that is devoid of a coordinated water molecule. The complex has an angle of 83.55° between the plane of L and bpy attached to one copper site, whereas it has an angle of 78.13° between the plane L and bpy attached to the other copper site. A 1,10-phenanthroline containing dinuclear copper(II) dipicolinate complex, [Cu(phen)(H₂O)(μ-L)Cu(phen)₂][CuL₂]·12H₂O (4), has been structurally characterized. It has an unusual carboxylate bridge.     

Equilibria in complexes of N-heterocyclic molecules,part 44. The thermogravimetric behaviour of a Schilt-Barbieri compound dicyanobis-(1,10-phenanthroline) iron(II) dihydrate,Fe(phen)2(CN)2 · 2H2O

Summary The thermogravimetric behaviour of Fe(phen)₂(CN)₂ · 2H₂O (phen = 1,10-phenanthroline) is discussed by comparison with that of phen · H₂O. It is shown that the crystal water of the Schilt-Barbieri compound is released only at 323.5 °C. After water loss, the complex decomposes immediately.Covalent hydrate formation for diimines or their complexes was discussed recently⁽¹⁾. In general, formation of covalent hydrates, containing moieties like, should be favoured by electron-withdrawing substituents while true hydrates, containing essentially intact molecules of water, are easily formed by electron-releasing substituents.Although no covalent hydrate has yet been established in a coordinated N-heterocycle by x-ray structural analysis, there are some cases which could involve covalent hydrate formation for diimines. One such is the strange claim that Fe(phen)₂(NCS)₂ · H₂O is diamagnetic at room temperature whereas anhydrous Fe(phen)₂(NCS)₂ is paramagnetic⁽²⁾, though this apparently well-studied system is almost certainly complicated by the existence⁽³⁾ of several distinct solid phases of composition Fephen₂(NCS)₂ · nH₂O. The differences in the n.m.r. spectra of the compounds [Fe(LL)(CN)₄]^2– (LL = phen, bipy and 5,5-Me₂-bipy) in D₂O are equally interesting. While the last two display the two-fold symmetry expected of the diimine ligand LL, the former shows⁽⁴⁾ an unexpected corresponding inequivalence.Moreover, the circular dichroism spectrum of optically active Fe(phen)₂(CN)₂ in acid solution shows the surprising feature that a c.d. band is observed in the visible region but the absorption in the u.v. region disappears⁽⁴⁾ completely. We have reconfirmed this finding. Despite the apparent ease of obtaining attractive crystals of the dihydrate Fe(phen)₂(CN)₂ · 2H₂O, there have been crystallographic problems that have so far prevented the solution of this problem by x-ray diffraction methods⁽⁵⁾, although we have been able to obtain the structure of the adduct (±)cis-[Fe(phen)₂(CN)₂]2Hg(CN)₂.In 1,10-phenanthroline monohydrate, despite crystallographic difficulties, there is now no doubt that the unit of structure is the hydrogen-bonded true hydrate. 1,10-Phenanthroline, despite being a substituted quinoline, seems not to form a classical Reissert compound, but the evidence for the (invariably assumed) simple structure of the Schilt-Barbieri compounds [Fe(LL)₂(CN)₂] is not strong. For example, there seems to be no report of an unsolvated solid.We therefore decided to compare the thermogravimetric behaviour of phen · H₂O and Fe(phen)₂(CN)₂ · 2H₂O.The compound phen · H₂O is commercially available (BDH Chemicals Ltd. Poole, England) while Fe(phen)₂(CN)₂ · 2H₂O was obtained by the method of Schilt⁽⁶⁾.On continuous heating under a atmosphere of dinitrogen, the water of phen · H₂O is released at 93 °C. The resulting anhydrous 1,10-phenanthroline is still stable, m.p. 117 °C (see Figure 2). The water molecules (one-step mechanism) of Fe(phen)₂(CN)₂ · 2H₂O are, however, released at the remarkably high temperature of 323.5 °C followed by an immediate decomposition of the anhydrous phase (see Figure 3).Other than the possibility of very strong hydrogen bonds being present in the structure of Fe(phen)₂(CN)₂ · 2H₂O, covalent hydrate formation could account for this unexpected behaviour. Further investigations on these Schilt-Barbieri compounds are in progress.     

Synthesis, spectral characterization and crystal structure of copper(II) complexes of 2-benzoylpyridine-N(4)-phenylsemicarbazone

An interesting series of nine new copper(II) complexes [Cu₂L₂(OAc)₂]·H₂O (1), [CuLNCS]·½H₂O (2), [CuLNO₃]·½H₂O (3), [Cu(HL)Cl₂]·H₂O (4), [Cu₂(HL)₂(SO₄)₂]·4H₂O (5), [CuLClO₄]·½H₂O (6), [CuLBr]·2H₂O (7), [CuL₂]·H₂O (8) and [CuLN₃]·CH₃OH (9) of 2-benzoylpyridine-N(4)-phenyl semicarbazone (HL) have been synthesized and physico-chemically characterized. The tridentate character of the semicarbazone is inferred from IR spectra. Based on the EPR studies, spin Hamiltonian and bonding parameters have been calculated. The g values, calculated for all the complexes in frozen DMF, indicate the presence of the unpaired electron in the d_x²-y² orbital. The structure of the compound, [Cu₂L₂(OAc)₂] (1a) has been resolved using single crystal X-ray diffraction studies. The crystal structure revealed monoclinic space group P2₁/n. The coordination geometry about the copper(II) in 1a is distorted square pyramidal with one pyridine nitrogen atom, the imino nitrogen, enolate oxygen and acetate oxygen in the basal plane, an acetate oxygen form adjacent moiety occupies the apical position, serving as a bridge to form a centrosymmetric dimeric structure.     

Self-assembly of four new extended architectures based on reduced polyoxometalate clusters and cadmium complexes

Four new [P₄Mo₆] cluster-based extended structures containing cadmium complexes, [Cd₃(4,4′-Hbpy)₂(4,4′-bpy)₂(H₂O)₈][Cd(H₂PO₄)₂(HPO₄)₄(PO₄)₂(MoO₂)₁₂(OH)₆]·7H₂O 1, (4,4′-Hbpy)₂[Cd(4,4′-bpy)₃(H₂O)₃][Cd(4,4′-bpy)(H₂O)]₂[Cd(H₂PO₄)₂(HPO₄)₄ (PO₄)₂(MoO₂)₁₂(OH)₆]·H₂O 2, [Cd₄(phen)₂(H₂O)₄][Cd(phen)(H₂O)]₂[Cd(HPO₄)₄ (HPO₄)₄(MoO₂)₁₂(OH)₆]·5H₂O 3 and [Cd₄(2,2′-bpy)₂(H₂O)₄][Cd(2,2′-bpy)(H₂O)]₂ [Cd(HPO₄)₄(HPO₄)₄(MoO₂)₁₂(OH)₆]·3H₂O 4 (4,4′-bpy=4,4′-bpyridine, phen=1,10-phenanthroline, 2,2′-bpy=2,2′-bpyridine), have been synthesized and characterized by elemental analysis, IR, TG and single crystal X-ray diffraction. The structure of compound 1 is constructed from the Cd[P₄Mo₆]₂ dimers linked by [Cd₃(4,4′-Hbpy)₂(4,4′-bpy)₂(H₂O)₈] subunits to generate a plane layer. Compound 2 consists of the positive 2D sheets that constructed from Cd[P₄Mo₆]₂ dimers linked by [Cd(4,4′-bpy)(H₂O)] complexes, then the 2D sheets are further linked up together to form a 3D supramolecular framework via extensive hydrogen-bonding interactions among the [P₄Mo₆] clusters, free 4,4′-bpy molecules, dissociated [Cd(4,4′-bpy)₃(H₂O)₃]²⁺ complexes and water molecules. Compounds 3 and 4 show new 2D layered structure, with Cd[P₄Mo₆]₂ building blocks connected by tetra-nuclear [Cd₄{(phen)₂/(2,2′-bpy)₂}(H₂O)₄] clusters and [Cd(phen/2,2′-bpy)(H₂O)] complexes. The fluorescent activities of compounds 3 and 4 are reported.     

Luminescent lanthanide complexes with 4-acetamidobenzoate: Synthesis, supramolecular assembly via hydrogen bonds, crystal structures and photoluminescence

Four new luminescent complexes, namely, [Eu(aba)₂(NO₃)(C₂H₅OH)₂] (1), [Eu(aba)₃(H₂O)₂]·0.5 (4, 4′-bpy)·2H₂O (2), [Eu₂(aba)₄(2, 2′-bpy)₂(NO₃)₂]·4H₂O (3) and [Tb₂(aba)₄(phen)₂(NO₃)₂]·2C₂H₅OH (4) were obtained by treating Ln(NO₃)₃·6H₂O and 4-acetamidobenzoic acid (Haba) with different coligands (4, 4′-bpy=4, 4′-bipyridine, 2, 2′-bpy=2, 2′-bipyridine, and phen=1, 10-phenanthroline). They exhibit 1D chains (1-2) and dimeric structures (3-4), respectively. This structural variation is mainly attributed to the change of coligands and various coordination modes of aba molecules. Moreover, the coordination units are further connected via hydrogen bonds to form 2D even 3D supramolecular networks. These complexes show characteristic emissions in the visible region at room temperature. In addition, thermal behaviors of four complexes have been investigated under air atmosphere. The relationship between the structures and physical properties has been discussed.     

Novel Copper(II) Thiodibenzoic Acid Coordination Polymers by in situ Extrusion of Sulfur from 2,2′‐Dithiodibenzoic Acid and the Unique Oxidation of Disulfide to Sulfate

Slow diffusion reaction of 2,2′‐dithiodibenzoic acid (dtdb) with CuCl₂ in the presence of N‐donor ligands results in the formation of different coordination polymers where both S–S and C–S scission and oxidation of S is observed. X‐ray diffraction analysis of [Cu(tdb)(phen)(H₂O)]₂ · 2H₂O.2DMF] ( 1 ), [Cu(tdb)(py)₂(H₂O)]₂ ( 3 ), and [Cu(tdb)(bipy)(H₂O)]₂ · 0.5H₂O ( 4 ) (tdb = thiodibenzoic acid, phen = phenanthroline, py = pyridine, bipy = 2,2′‐bipyridine) show that the metal ions are coordinated to the carboxylate oxygen atoms of the in situ generated tdb ligand in a monodenate fashion. In [Cu(phen)(SO₄)₂(H₂O)₂]_n ( 2 ) and [Cu(bipy)(SO₄)₂(H₂O)₂]_n ( 5 ), the sulfur is oxidized to sulfate ions prior to coordination with the metal. Complex 1 has a dimeric structure with π–π interactions between the phen ligands, whereas 3 and 4 form 1D polymeric chains.     

A kinetic study of the 1, 10-phenanthroline-catalysed iron(III) oxidation of epimeric aldo-, and D-, and L-ketohexoses

Summary Fe^III in H₂SO₄ medium does not oxidize sugars even at the reflux temperature, however, the reaction is catalysed by trace amounts of 1,10-phenanthroline (phen). A kinetic study shows that the oxidation rate increases as [phen] increases and exhibits a fractional order dependence upon [phen]. The orders with respect to [Fe^III] and [carbohydrate] are unity. The oxidation rate decreases as [HSO^4/–] and [H₂SO₄] increase. A plausible mechanism is proposed involving participation of an [Fe^III-phen] precursor and sugar in the rate-determining step.     

Synthesis, crystal structures and characterization of four coordination polymers based on 5-amino-2,4,6-triiodoisophthalic acid

One homochiral 1D coordination polymer [Cu(ATIBDC)(2,2′-bipy)]·3H₂O·CH₃OH (1) and three achiral 1D coordination polymers: [Cd(ATIBDC)(2,2′-bipy)(H₂O)]·3H₂O (2), [Cd(ATIBDC)(phen)(H₂O)]·4H₂O (3), and [Mn(ATIBDC)(phen)₂]·5H₂O (4) have been synthesized and characterized (H₂ATIBDC=5-amino-2,4,6-triiodoisophthalic acid, 2,2′-bipy=2,2′-bipyridine, and phen=1,10-phenanthroline). Extended high dimensional network architectures are further constructed with the help of weak secondary interactions, such as hydrogen bonding, aromatic stacking, and halogen bonding (C-I…π and C-I…N/O). Complex 1 crystallizes in the monoclinic system with chiral space group P2(1) and exhibits a right-handed 2₁ helical chain structure. The homochirality of 1 was confirmed by CD spectrum. Interestingly, two new configurations of decameric water cluster are found in 3 and 4. The acyclic tetrameric cluster (H₂O)₃(CH₃OH) in 1 and (H₂O)₄ in 2 array into highly ordered helical infinite chains. Thermal stabilities of all the complexes have been studied. Solid state fluorescent properties of the Cd(II) complexes have been explored.     

Copper(II) complexes with 1,2,4-triazolo[1,5-a] pyrimidine and its 5,7-dimethyl derivative

Several Cu(II) complexes with 1,2,4-triazolo[1,5-a]pyrimidine (tp) and its 5,7-dimethyl derivative (dmtp) have been isolated and structurally characterized. Five of them are mononuclear and contain 1,10-phenanthroline (phen) or ethylenediamine (en) as auxiliary ligands, their formula being [Cu(H₂O)(phen)(tp)₂](ClO₄)₂ · H₂O, [Cu(H₂O)(phen)(dmtp)₂](ClO₄)₂, [Cu(NO₃)(H₂O)(phen)(tp)](NO₃), [Cu(H₂O)₂(en)(tp)₂](ClO₄)₂ and [Cu(H₂O)₂(en)(dmtp)₂](ClO₄)₂. In all these compounds the tp or dmtp ligand is monodentately coordinated via the nitrogen atom in position 3. The auxiliary ligand influences the coordination number, which is five when this ligand is phen and six when it is en whereas the number of triazolopyrimidine ligands linked to the metal seems to be influenced by the nature of the counteranion. A dinuclear compound with tp has also been isolated, its formula being [Cu₂(OH)(H₂O)_2.5(tp)₅](ClO₄)₃·(H₂O)_1.5, with both metal atoms linked by an hydroxydo group and by a tp bridging ligand, coordinated to one of the copper atoms via N3 and to the other via N4. This compound has several unusual features among the metal complexes with triazolopyrimidine derivatives: the presence of two different kinds of bridging moieties, the coexistence of bridging and terminal ligands and the formation of a N3–N4 bridge for a Cu(II) dinuclear compound for a derivative without exocyclic oxygen atoms.     

Hydrothermal syntheses and characterization of cobalt(II) and nickel(II) complexes of 1,3-adamantanedicarboxylic acid and 1,10-phenanthroline

Two coordination complexes, namely [Co(phen)(H₂O)L]·H₂O and [Ni₂(phen)₂(H₂O)₂L₂]·4H₂O (phen = 1,10-phenanthroline, H₂L = 1,3-adamantanedicarboxylic acid) have been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction. [Co(phen)(H₂O)L]·H₂O consists of 1D chains of the complex plus lattice H₂O molecules. Interchain hydrogen bonds and π–π stacking interactions assemble the 1D chains into 2D layers. [Ni₂(phen)₂(H₂O)₂L₂]·4H₂O is a binuclear complex which is assembled into a 3D supramolecular structure by strong hydrogen bonds and π–π stacking interactions. Both complexes were characterized by physico-chemical and spectroscopic methods.     

Di-, tri-, tetranuclear clusters and polymeric cadmium compounds: Syntheses, structures and fluorescent properties with various linking fashions and high stability of orotates under the condition of strong bases

Assembly reactions of orotic acid (H₃dtpc ) and CdCl₂·2.5H₂O or CdSO₄·8H₂O yielded four new cadmium compounds {[Cd(H₂dtpc)(phen)(H₂O)₂]·(H₂dtpc)·4H₂O}₂ (1: solution reaction, pH=4-5, in addition of phen), [Cd₃(dtpc)₂(phen)₅]·13H₂O (2: hydrothermal reaction, initial pH=14, final pH=7.5), [Cd(Hdtpc)(H₂O)₃]₄ (3: solution reaction, initial pH=6.5, final pH=6.0), {[Cd(Hdtpc)(phen)(H₂O)]·H₂O}_n (4: hydrothermal reaction, initial pH=8; final pH=6.5), respectively. Compounds 1-4 have been characterized by IR, thermogravimetric analyses (TGA), photoluminescence analyses, single-crystal and powder X-ray diffraction (PXRD). Compound 1 is a binuclear, 2 is a trinuclear, 3 is a tetranuclear structure, and 4 possesses one-dimensional chain framework, respectively, in which the orotate ligands show seven different linking fashions in 1-4. The orotate ligands as trivalence anions are observed in the formation of orotate-compounds, in which the orotates show high stability under the extreme condition of strong basic solution, high temperature and pressure.