Neil R. Brooks

Metalloenzyme inspired dizinc catalyst for the polymerization of lactide

A new dizinc-monoalkoxide complex supported by a dinucleating ligand was structurally characterized and shown to be a highly active catalyst for the controlled polymerization of lactide.

Differential metathesis reactions of 2,2′-bipyridine and 1,10-phenanthroline complexes of cobalt(II) and nickel(II): cocrystallization of ionization isomers {[cis-Ni(phen)2(H2O)2][cis-Ni(phen)2(H2O)Cl]} (PF6)3⋅4.5H2O, and a synthetic route to asymmetric tris-substituted complexes

Addition of ammonium hexafluorophosphate to aqueous solutions of M(chelate)Cl2 [chelate = 2,2′-bipyridine and 1,10-phenanthroline, M = Co(II) and Ni(II)] produce different metathesis products. Tris-substituted chelate complexes are produced in the case of bipyridine; however {[cis-M(phen)2Cl(H2O)][ cis-M(phen)2(H2O)2]}(PF6)3⋅4.5H2O, a unique example of cocrystallized ionization isomers, is produced with phenanthroline. Extended hydrogen bonding interactions connect [M(phen)2Cl(H2O)]+ and [M(phen)2(H2O)2]2+ cations in the crystal lattice. Because metathesis reactions using phenanthroline produce disubstituted complexes, the convenient synthesis of symmetric [Ni(phen)3]2+ and asymmetric [Ni(phen)2(5-nitrophenanthroline)]2+ is described.

Characterization of an asymmetric M(chelate)2(μ-Cl)2MCl2 dimer and isolation of corresponding DMSO adducts: X-ray crystal structures of Co(phen)2(μ-Cl)2CoCl2.C4H8O and M(chelate)Cl2(DMSO)x(Co, x = 1; Ni, x = 2) complexes

AbstractIn aqueous solution, [M(chelate)Cl2]x (chelate = 2,2′-bipyridine, 1,10-phenanthroline) complexes can disproportionate to produce M(chelate)2n+ species that contain two chelating ligands. After extraction with organic solvent,Co(phen)2(μ-Cl)2CoCl2(1) has been characterized by X-ray diffraction (monoclinic, C2/c, a = 10.278(2)Å, b = 22.026(5)Å, c = 12.941(3)Å, β = 103.959(4)°, Z = 4, 2414 reflections [I ≥ 2σ (I)], R1 = 0.0321, wR2 = 0.0864). However, addition of [M(chelate)Cl2]x starting materials to dimethyl sulfoxide produces complexes that retain a single chelate ligand. The pentacoordinate complex Co(bpy)Cl2DMSO (2) has been structurally characterized (triclinic, P

Glyme−Lithium Bis(trifluoromethanesulfonyl)imide and Glyme−Lithium Bis(perfluoroethanesulfonyl)imide Phase Behavior and Solvate Structures

{\bar 1}

Triglyme−Li+ Cation Solvate Structures: Models for Amorphous Concentrated Liquid and Polymer Electrolytes (I)

, a = 7.824(2)Å, b = 9.570(4)Å, c = 10.025(2)Å, α = 83.24(3)°, β = 87.14(2)°, γ = 83.35(3)°, Z = 2, 2455 reflections [I ≥ 2σ (I)], R1 = 0.0278, wR2 = 0.0747). In the case of nickel, two different geometric isomers are observed, depending on the chelate identity: trans-(DMSO)2Ni(bpy)Cl2⋅ DMSO (3) (monoclinic, P21/c, a = 10.9149(8)Å, b = 12.1287(9)Å, c = 17.0044(13)Å, β = 98.610(1)°, Z = 4,3519 reflections [I ≥ 2σ (I)], R1 = 0.0209, wR2 = 0.0560) and cis-(DMSO)2Ni(phen)Cl2 (4) (monoclinic, P21/c, a = 8.404(2)Å, b = 14.051(4)Å, c = 16.710(4)Å, β = 92.44(3)°, Z = 4, 3069 reflections [I ≥ 2σ (I)], R1 = 0.0691, wR2 = 0.1782).

Derivatization, complexation, and absolute configurational assignment of chiral primary amines: application of exciton-coupled circular dichroism.

The title compounds, poly[[[bis(2-methoxyethyl) ether]lithium(I)]-di-mu(3)-trifluoromethanesulfonato-lithium(I)], [Li(2)(CF(3)SO(3))(2)(C(6)H(14)O(3))](n), and poly[[[bis(2-methoxyethyl) ether]lithium(I)]-di-mu(3)-trifluoroacetato-dilithium(I)-mu(3)-trifluoroacetato], [Li(3)(C(2)F(3)O(2))(3)(C(6)H(14)O(3))](n), consist of one-dimensional polymer chains. Both structures contain five-coordinate Li(+) cations coordinated by a tridentate diglyme [bis(2-methoxyethyl) ether] molecule and two O atoms, each from separate anions. In both structures, the [Li(diglyme)X(2)](-) (X is CF(3)SO(3) or CF(3)CO(2)) fragments are further connected by other Li(+) cations and anions, creating one-dimensional chains. These connecting Li(+) cations are coordinated by four separate anions in both compounds. The CF(3)SO(3)(-) and CF(3)CO(2)(-) anions, however, adopt different forms of cation coordination, resulting in differences in the connectivity of the structures and solvate stoichiometries.