Deyuan Kong

Dinuclear metal complexes and ligands: stabilities and catalytic effects

Abstract Two new dinucleating macrocyclic ligands, 1 and 2, were designed and synthesized in our laboratory. Two phenolate donor groups were built into the macrocycles to increase the binding affinity for Fe(III). The stabilities of the iron(III) complexes of 1 and 2 are shown. These ligands were also found to complex iron(II) in the same manner, with the two Fe(II) ions bridged by the two phenolate oxygens. The stability constants of the Fe(II) chelates of 1 and 2 are also shown. The Fe(II) complexes were found to catalyze the oxidation of hydrocarbons, such as adamantane, by molecular oxygen.

Novel 30-membered octaazamacrocyclic ligand: synthesis, characterization, thermodynamic stabilities and DNA cleavage activity of homodinuclear copper and nickel complexes

A new 30-membered octazamacrocyclic ligand: 4,6,9,12,20,23,26,29-octaaza-35.36-dihydroxy-16,33-dimethyl-tricyclo[29.3.1.1 1 4 , 1 8 ]hexatriaconta-1(35),18(36),15,17,31,33-hexaene (L or BTBD) has been synthesized and characterized. Its coordination chemistry toward Cu(II) and Ni(II) ions has been investigated extensively by potentiometric titration in 1:1 or 1:2 (L-M) aqueous systems. L shows high complexation ability with Cu(II) and Ni(II) ions in 1:1 systems with formation constants: log K[ML] = 24.01 (M = Cu), 21.04 (M = Ni), respectively. In 1:2 (L-M) systems, two metal ions were suggested to enter into the cavity separately and locate in half of the compartment without formation of μ-oxo bridged core. BTBD served as N 8 O 2 -2 ligand to divalent binuclear copper and nickel complexes with similar stability constants (log K[M 2 L] = 15.38, 15.36, respectively). [C 3 0 H 5 0 Cu 2 N 8 O 2 ](ClO 4 ) 2 .CH 3 OH.2(H 2 O) (1) crystallizes in the monoclinic space group P2 1 /n, a = 7.9662(7), b = 14.5925(4), c = 11.614(10) A, β = 105.187(4)°, V = 3905.5(6) A 3 and Z = 4. Each copper is complexed by half of the coordination sites of the dinucleating macrocycle, and completes square pyramidal polyhedron. [C 3 0 H 5 0 N 8 Ni 2 O 2 (H 2 O) 2 ](ClO 4 ) 2 .CH 3 OH.3(H 2 O) (2) crystallizes in the triclinic space group P1, a = 10.5559(5), b = 14.6947(7), c = 15.3025(10) A, α = 65.5470(10), β = 80.4650(10), γ = 72.7392(10)°, V = 2060.92(17) A 3 and Z = 2. The X-ray crystallographic results demonstrate that each nickel ion resides in the N 4 O - site and forms six-coordinated octahedron with exogenous solvents at the apex. Dinuclear copper complexes have been found have cleavage ability toward supercoiled pBR 322 DNA in the presence of H 2 O 2 . EPR and UV results showed that the possible cleavage mechanism was via Cu(II)-O-O-Cu(II) peroxide and leads to DNA oxidative cleavage.

Synthesis, structural characterization of tetraazamacrocyclic ligand, five-coordinated zinc(II) complex

Abstract 1,4,7,10-tetrakis(2-cyanoethyl-)-1,4,7,10-tetraazacyclododecane(L) and Zn (1), Y(2), Er(3), Pr(4), Gd(5) complexes with L was synthesized and characterized. All metal complexes are in the general formula: [M(L)(H2O)](NO3)2 (M=Zn, n=1); and [M(L)(NO3)2]NO3·mH2O·nCH3CN (M=Y, Er, m=5, n=0; M=Pr, Gd, m=0, n=1, 1.5). Both ionic nitrate ion and bidentate coordinated nitrate ions are existed in complex 2–5. Structures of diprotonated L and zinc complexes were determined by X-ray diffraction. L was crystallized in diprotonated nitrate salt. In zinc complex, the central metal ion was coordinated with four nitrogen atoms of macrocyclic ligand and oxygen atom of water molecule, which defined a tetragonal pyramidal polyhedron. The bond lengths of ZnN are in the range of 2.160(5)–2.177(6) A and the bond length of ZnO is 1.918(4) A.

A novel copper organophosphonate with a pore-like 3D framework and Cu–Cu magnetic ordering

H2O3PCH2NH2+CH2PO3H− was hydrothermally reacted with Cu(II) in aqueous solution at a 1 : 1 ratio, forming Cu3[NH2(CH2PO3)2]2 (1). Two kinds of coordination environments exist around the central copper ions: a distorted square planar Cu(1) ion and an octahedral Cu(2) ion. They are bridged with one terminal oxygen atom forming a 3D-coordination framework of layers sharing corners. Novel antiferromagnetic coupling between the two kinds of Cu units was observed at 15 K, followed by ferromagnetic ordering at 9 K.

Macrocyclic dinuclear Zn(II) complexes: synthesis, structure and hydrolysis of tris(p-nitrophenyl) phosphate

A series of mono- and dinuclear zinc complexes of 3,6,9,17,20,23-hexaaza-29,30-dihydroxy-13,27-dimethyl-tricyclo[23,3,1 1 1 , 1 5 ]-triaconta-1(28),11,13,15(30),25,26-hexaene (H 2 L or BDBPH) have been defined in solution by potentiometry. The crystal structure of [Zn 2 C 2 6 H 4 0 N 6 O 2 (CH 3 OH) 2 ].Br 2 has been determined by X-ray. Each zinc ion is coordinated to three nitrogen atoms, a bridged-phenolic oxygen atom, and a methanolic oxygen atom, which define a six-coordinated octahedron. Bond lengths of Zn N are in the range of 2.104(3) 2.120(3) A and distances between Zn and O (bridged-phenolic oxygen) are 2.052(2), 2.062(2) A. respectively. The dinuclear complexes: [Zn 2 L] 2 and [Zn 2 L(OH)] + play crucial roles in hydrolytic reaction of tris(4-nitrophenyl)phosphate. A possible mechanism showed that [Zn 2 L(OH)] + acts as a nucleophile and [Zn 2 L] 2 + stabilizes the formation of the intermediate: [Zn 2 L BNP].

Complexation of Cu(II)M(II) (M=Cd, Co, Ni, Zn) heterodinuclear compounds of an octacoordinate hexaazamacrocyclic ligand

Abstract In this paper the investigation of the formation of HDTHCu heterodinuclear complexes of Zn(II), Cd(II),Co(II) and Ni(II) and HDTHCo heterodinuclear complexes with Ni(II) and Pb(II) in aqueous solution by control of the stoichiometry of metal ions and HDTH as well as p[H] of the solution (HDTH is a dinucleating 28-membered hexaazadiphenol macrocyclic ligand 3,7,11,19,23,27-hexaaza-33,34-dihydroxy-15,31-dimethyl-tricyclo-tetratriaconta-1(32),13,15,17(34),29(33),30-hexaene). The pH potentiometric method has been utilized successfully to determine formation constants while in turn determine the distribution of species present in the solution as a function of p[H]. Spectrophotometry was used to investigate the formation process of the heterodinuclear complexes. The X-ray crystal structures of two homodinuclear complexes of Cu(II) and Zn(II) are also reported. These results show that the two moieties of the ligand react with Cu(II) ions separately, functioning like two independent binding groups. These studies suggested that the Cu(II) complexes of the macrocyclic ligand can form the basis for discrete and stable heterodinuclear complexes and can be used to investigate the complexation in solution by taking Cu(II) as one moiety of the heterodinuclear complex.

Sulfur‐Containing Chiral Bis(oxazolines) Tested in Copper‐Catalyzed Asymmetric Cyclopropanation

Abstract The novel C2‐symmetric sulfur‐containing chiral bis(oxazoline) compound has been synthesized and characterized by X‐ray crystallography. Highly enantioselective and diastereoselective cyclopropanation reactions have been performed using the copper‐bis(oxazoline) catalyst.

Inorganic–organic hybrid metal complexes: 24-membered hexaazamacrocyclic dinuclear nickel complexes hybridized with CdBr 4 2−

Abstract The 24-membered macrocyclic mononuclear cadmium complex reacts with Ni(ClO4)2 in solution and unexpected dinuclear nickel complex was obtained with [CdBr4]2− as counter ions. In the homodinuclear nickel complex, two different coordination environmental entities were observed. One of these is a five-coordinated dinuclear species, the other is a six-coordinated dinuclear species [Ni(1A)2C26H40N6O2(H2O)2]. In [Ni(1A)2C26H40N6O2(H2O)2], nickel ion is coordinated to three nitrogen atoms, one phenolic oxygen from the macrocyclic ligand, and with one exogenous water molecule to complete an octahedron. In [Ni(1B)2C26H40N6O2], each nickel ion is five-coordinated without solvent interaction. [CdBr4]2− anions are located in the lattice and serve as hybrid bridges to connect two different molecules and form two layer arrays along the c axis. The whole molecule is described as an ion pair with a two-dimensional hydrogen bonding network. The average bond lengths of Ni–N and Ni–O(phenolic oxygen) are 2.083, 2.028 A.

Mononuclear and Dinuclear Cobalt Complexes and its Dioxygen Adduct with a New 24-membered Hexaaza Macrocyclic Ligand

Abstract Dinucleating 24-membered hexaazadiphenol macrocyclic ligand 3,6,9,17,20,23-hexaaza-29,30-dihydroxy-13,27-dimethyl-tricyclo[23,3,1,111,15] triaconta-1(29), 11,13,15(30),25,27-hexaene (L or BDBPH), is prepared by the NaBH4 reduction of the Schiff base obtained from [2+2] template condensation of 2,6-diformyl-p-cresol with diethylenetriamine. The ligand maintains dinuclear integrity for cobalt (II) while facilitating the formation of bridging phenolate dicobalt cores. Potentiometric equilibrium studies indicate that a variety of protonated, mononuclear and dinuclear cobalt (II) complexes form from p[H] 2 through 11 in aqueous solution. The protonation constants of this ligand and stability constants of the 1:1, 1:2 ligand: cobalt(II) complexes were determined in KCl supporting electrolyte (μ = 0.100 M) at 25°C. The mechanism for the formation of dinuclear dioxygen cobalt(II) complexes is also described. The stability constants of mononuclear and dinuclear cobalt complexes were determined under nitrogen. Preliminary results show that the dinuclear dioxygen cobalt (II) complexes do not catalyze hydroxylation of adamantane in the presence of H2S as two-electron reductant.

Synthesis and structure of copper-DMPLED complex, a bifunctional ligand with positive charged pyridine rings

Abstract N,N′-bis(3-hydroxy-1,2-dimethyl-5-hydroxymethyl-4-pyridyl-methyl)ethylenediamine-N,N′-diacetic acid, DMPLED and its copper complex has been synthesized and characterized with FAB-MS, elemental analysis and X-ray diffraction. The polyhedra of the Cu complex is described as a Jahn–Teller distorted octahedron with two axes elongated (Cu–O(1), Cu–O(4) are 2.481(4) and 2.676(4) A, respectively). Cu–O(7), Cu–O(8), Cu–N(1) and Cu–N(2) are 1.914(4), 1.929(4), 1.998(6) and 2.019(5) A, respectively.