Ming-Lin Guo

Quaternary ammonium decatungstate catalyst for oxidation of alcohols

This work describes the use of hydrogen peroxide as oxidant for the selective oxidation of some alcohols in the presence of hexadecyl trimethyl ammonium decatungstate catalyst under simple reaction conditions. It includes the oxidation of cyclohexanol to cyclohexanone in the temperature range of 90 to 100 °C for 2 hours with 89.1% yield and 92.3% cyclohexanol conversion and the oxidation of hexanol and octanol at a temperature of 90 °C or reflux for 12–17 hours with 86.2–93.7% yields and 93.5–98.8% carboxylic acid selectivity.

Poly[[diaqua(μ3‐2,2‐dimethylmalonato)cadmium(II)] tetrahydrate]

In the title complex, {[Cd(C(5)H(6)O(4))(H(2)O)(2)].4H(2)O}(n), the dimethylmalonate-cadmium metal-organic framework co-exists with an extended structure of water molecules, which resembles a sodalite-type framework. In the asymmetric unit, there are five independent solvent water molecules, two of which are in special positions. The Cd atoms are eight-coordinated in a distorted square-antiprismatic geometry by six O atoms of three different dimethylmalonate groups and by two water molecules, and form a two-dimensional honeycomb layer parallel to the bc plane. Two such layers sandwich the hydrogen-bonded water layer, which has a sodalite-type structure with truncated sodalite units composed of coordinated and solvent water molecules. This work is the first example of a dimethylmalonate cadmium complex containing truncated sodalite-type water clusters.

Poly[μ-aqua-diaqua-μ4-malonato-μ3-malonato-barium(II)nickel(II)]

The title complex, [BaNi(C3H2O4)2(H2O)3]n, is polymeric, with two non-equivalent malonate dianions bridging one Ni atom and five different Ba atoms. The Ni atoms have a distorted octahedral (NiO6) environment, and are coordinated by four malonate O atoms in a planar arrangement and two water molecules in axial positions. The Ba atom may be described as a BaO9 polyhedron in a monocapped square-antiprismatic environment, which involves two water molecules and seven O atoms from different malonate ligands. The three-dimensional structure is further maintained and stabilized by hydrogen bonds.

Poly[aqua-mu3-2,2-dimethylmalonato-zinc(II)].

The title complex, [Zn(C5H6O4)(H2O)]n, has a two-dimensional layer structure. The Zn atoms, in a geometry that is closer to trigonal bipyramidal than square pyramidal, are coordinated by two O atoms of a bidentate dimethylmalonate ligand, two O atoms of monodentate dimethylmalonate ligands and one O atom from the aqua ligand. The crystal structure is characterized by the intralayer motif of a hydrogen-bonded network. Neighboring layers are linked together to build up a three-dimensional network via van der Waals forces.

Poly[tetraaquadi-μ4-malonato-barium(II)zinc(II)]

The title complex, [BaZn(C3H2O4)2(H2O)4]n, is polymeric, due to the connectivity brought about by each malonate dianion bonding to two different Zn(II) cations and two different Ba(II) cations. The Ba(II) cations, on crystallographic twofold axes, have slightly distorted square-antiprismic coordination, with Ba-O distances ranging from 2.795 (2) to 2.848 (2) A. The Zn(II) cations, which lie on crystallographic centres of symmetry, have distorted octahedral coordination, with Zn-O bonds in the range 2.0364 (19)-2.3248 (18) A. The water molecules participate in extensive O-H...O hydrogen bonding. The structure comprises alternating layers along [100], with one type containing Zn(II) cations and malonate dianions, while the other is primarily composed of Ba(II) cations and water molecules.

Poly[[aqua-μ3-2,2-dimethylmalonato-copper(II)] monohydrate] and poly[aqua-μ3-2,2-dimethylmalonato-copper(II)]

The coordination mode of the dimethylmalonate ligand in the two title Cu(II) complexes, {[Cu(C(5)H(3)O(4))(H(2)O)]·H(2)O}(n), (I), and [Cu(C(5)H(3)O(4))(H(2)O)](n), (II), is the same, with chelated six-membered, bis-monodentate and bridging bonding modes. However, the coordination environment of the Cu(II) atoms, the connectivity of their metal-organic frameworks and their hydrogen-bonding interactions are different. Complex (I) has a perfect square-pyramidal Cu(II) environment with the aqua ligand in the apical position, and only one type of square grid consisting of Cu(II) atoms linked via carboxylate bridges to three dimethylmalonate ligands, with weak hydrogen-bond interactions within and between its two-dimensional layers. Complex (II) has a coordination geometry that is closer to square pyramidal than trigonal bipyramidal for its Cu(II) atoms with the aqua ligand now in the basal plane. Its two-dimensional layer structure comprises two alternating grids, which involve two and four different dimethylmalonate anions, respectively. There are strong hydrogen bonds only within its layers.

Poly[[tetraaquatris(μ3-2,2-dimethylmalonato)dilanthanum(III)] monohydrate]

In the title complex, {[La(2)(C(5)H(6)O(4))(3)(H(2)O)(4)].H(2)O}(n), the La atoms are connected by bridging O atoms from carboxylate groups to build, through centres of inversion, two-dimensional layers parallel to the ac plane containing decanuclear 20-membered rings. The coordinated water molecules are involved in intralayer hydrogen-bond interactions. Adjacent layers are linked via hydrogen bonding to the solvent water molecules. This work represents the first example of a new substituted malonate-lanthanide complex.

1-methylpiperazine-1,4-diium 4-nitrophthalate(2-) 4-nitrophthalic acid monohydrate

The title adduct, C5H14N2(2+).C8H3NO6(2-).C8H5NO6.H2O, crystallizes in the monoclinic space group P2(1). All O atoms of the 4-nitrophthalate anions and neutral 4-nitrophthalic acid molecules are involved in hydrogen bonding with the piperazine dication and the water molecule of crystallization.

Poly[diaquabis(μ3‐2,2‐dimethylpropanedioato)calcium(II)copper(II)]

The title complex, [CaCu(C(5)H(6)O(4))(2)(H(2)O)(2)](n), is the first heterobimetallic complex based on a substituted malonate dianion. The Cu(II) cation and two independent 2,2-dimethylmalonate (or 2,2-dimethylpropanedioate) dianions build up a robust dianionic [Cu(C(5)H(6)O(4))(2)](2-) complex, which acts as a building block to coordinate to four Ca(2+) cations. Each Cu(II) centre is in a four-coordinate square plane of dimethylmalonate O atoms, while each Ca(II) atom is in an eight-coordinate distorted bicapped trigonal-prismatic environment of six O atoms from four different dimethylmalonate groups and two water molecules. This arrangement creates a two-dimensional layer connectivity of the structure. The dianionic [Cu(C(5)H(6)O(4))(2)](2-) units are involved in different intermolecular hydrogen-bonding interactions with water molecules via the formation of hydrogen-bonded rings of graph sets R(1)(2)(8) and R(6) within this layer. The crystal was nonmerohedrally twinned by rotation about [011] with a major twin volume fraction of 0.513 (3).

Poly[[diaquabis(μ2-1-oxo-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane-4-carboxylato)copper(II)] dihydrate]

The asymmetric unit of the title complex, {[Cu(C(5)H(6)O(6)P)(2)(H(2)O)(2)] x 2 H(2)O}(n), consists of half a Cu atom, one complete 1-oxo-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane-4-carboxylate anion ligand and two non-equivalent water molecules. The Cu atom lies on a crystallographic inversion centre and has an elongated axially distorted octahedral environment. A two-dimensional layer structure parallel to (100) is formed as a result of the connectivity brought about by each anion bonding to two different Cu atoms via a carboxylate O atom and a bridging O atom of a C-O-P group. The water molecules participate in extensive O-H...O hydrogen bonding. Neighbouring layers are linked together by intermolecular hydrogen-bonding interactions. The crystal structure is characterized by intra- and interlayer motifs of a hydrogen-bonded network. This study demonstrates the usefulness of carboxylates with caged phosphate esters in crystal engineering.