Kin-Chung Lam

1,1′-Spirobiindane-7,7′-diol: a novel, C2-symmetric chiral ligand

Abstract A novel, C2-symmetric chiral diol (16) was prepared in six steps from m-anisaldehyde and resolved via its bis- l -menthoxycarboxylate.

Unambiguous exchange-correlation energy density

An exact exchange-correlation energy density is constructed using only knowledge of the density dependence of the exchange-correlation energy functional, EXC. The energy density does not depend on the choice of origin, and allows direct comparison between any functional approximation and the exact quantity. The asymptotic behavior of this energy density contains the exact ionization potential. The relative performance of approximation energy functionals is reflected in this energy density, i.e., the local approximation is moderately accurate, generalized gradient approximations work better, while hybrids with exact exchange work best. The intershell spike in atoms is highlighted in this energy density. The energy density can also be calculated for solids, and has implications for many areas of density-functional theory.

Triphosphane formation from the terminal zirconium phosphinidene complex [Cp2ZrPDmp(PMe3)] (Dmp=2,6-Mes2C6H3) and crystal structure of DmpP(PPh2)2

Abstract The new terminal phosphinidene complex [Cp2ZrPDmp(PMe3)] (Dmp=2,6-Mes2C6H3; 1) was prepared in 81% yield by the reaction of [Li(Et2O)][P(H)Dmp] with [Cp2Zr(Me)Cl] in the presence of excess PMe3. Compound 1 reacts with Ph2PCl to produce selectively the sterically congested triphosphane DmpP(PPh2)2 (2) and [Cp2ZrCl2] in high yields. The structure of 2 obtained by X-ray diffraction analysis of a single crystal reveals phosphorus–phosphorus bond lengths of 2.251(2) and 2.234(2) A and a PPP bond angle of 105.46(6)°.

Two novel zinc(II) complexes of the 1,8-cross-bridged cyclam ligand and their structures

Abstract Without special precautions to exclude moisture or protic solvents, cross-bridged cyclam ligand 1 was found to readily complex zinc dichloride and yield two types of cis-folded complexes in the solid-state; one a chloride-bridged dimer and the other an aqua complex featuring a coordinated [ZnCl4]2− counterion.

Novel silver(I)–organic coordination polymers: conversion of extended structures in the solid state as driven by argentophilic interactions

Structurally distinct coordination polymers [Ag(bpp)]ClO4 1 and [Ag(bpp)]PF6 2 [bpp = 1,3-bis(4-pyridyl)propane] have been assembled; the conversion of 1 into 2 on treatment with NaPF6 is driven by argentophilic interactions and is the first such transformation reported for silver(I)-organic coordination polymers.

Oxidative addition reaction of perfluoro-n-butyl iodide to (COD)PtMe2 to give (COD)PtMe(nC4F9).: The molecular structure of (COD)PtMe2

Abstract Reaction of (COD)PtMe2 (COD=1,5-cyclooctadiene) with one molar equivalent of C4F9I in hexanes produces the perfluoroalkylplatinum product (COD)PtMe(C4F9) (1) along with the known Pt(IV) complex [PtMe3I]4. This result stands in contrast to previous reports that attempts to synthesize platinum complexes with fluoroalkyls larger than CF3 gave only inseparable mixtures. An essential condition to the controlled synthesis of 1 is the use of only one equivalent of perfluoroalkyl iodide. Similar reactions reported previously employed an excess of iodoperfluorocarbon, which gave rise to mixtures of products due to successive oxidative addition and reductive elimination reactions. The X-ray crystal structure (COD)PtMe2 was determined.

Unambiguous exchange–correlation energy density for Hooke's atom

Recently, we used Helmholtzs theorem to construct an unambiguous exchange)correlation energy density for use in density functional theory. This energy density requires only knowledge of the density dependence of the exchange)correlation energy functional, E , for its calculation. We calculate this energy density for Hookes XC . atom in three different regimes: the high-density or weakly correlated limit; a moderate density, comparable to that of the He atom; and a low density, in which the system is strongly correlated. We compare the exact unambiguous energy density with approximate energy densities found from approximate energy functionals. The exchange)correlation energy can be deduced directly from the density in the highly correlated limit and a new formula for the high-density limit of the correlation energy is given. Q 1998 John Wiley & Sons, Inc. Int J Quant Chem 70: 583)589, 1998

Synthesis, characterization and reactivity of copper(I) imidazole complexes based on a cavitand ligand design

Two new cavitand-based imidazolyl ligands and their corresponding copper(I) complexes are reported; the tris(imidazole) complex is substitutionally inert while the bis(imidazole) complex readily reacts with CO, PMe3, N3− and SCN−. p

Synthesis and characterization of siloxy-substituted diene and dienyl complexes of the Ru(C5Me5) fragment

Abstract The reaction of a 2-siloxy-4-methyl-1,3-pentadiene with the Ru(C 5 Me 5 )Cl tetramer was observed to lead first to an isolable Ru(C 5 Me 5 )(η 4 -diene)Cl complex, which subsequently was found to lose HCl readily, leading to the expected Ru(C 5 Me 5 )(η 5 -2-siloxy-4-methylpentadienyl) complex. Both species have been characterized spectroscopically and through X-ray diffraction studies.

Dioxygen mediated oxo-transfer to an amine and oxidative N-dealkylation chemistry with a dinuclear copper complex

Reaction of dioxygen with a dinuclear copper(I) complex of a new binucleating ligand is described, wherein a peroxo–dicopper(II) (Cu2–O2) intermediate leads to an oxo-transfer reaction to give an N-oxide of an N-benzyl internal ligand substrate; additionally observed regioselective oxidative N-dealkylation chemistry occurs.