Norris W. Hoffman

Sweet success: ionic liquids derived from non-nutritive sweetenersElectronic supplementary information (ESI) available: experimental details; IR spectra. See http://www.rsc.org/suppdata/cc/b3/b313068a/

The anions of the sweeteners saccharin and acesulfame form ionic liquids when paired with a variety of organic cations.

Ligand bond energies in cis- and trans-[L-Pd(PH3)2Cl]+ complexes from coupled cluster theory (CCSD(T)) and density functional theory.

The Pd-L ligand bond dissociation energies (BDEs) of cis- and trans-[L-Pd(PH(3))(2)Cl](+) were predicted using coupled cluster CCSD(T) theory and a variety of density functional theory (DFT) functionals at the B3LYP optimized geometries. trans-[L-Pd(PH(3))(2)Cl](+) is the more stable isomer when Pd forms a donor-acceptor bond with a C atom of the ligand, including the π-bond in norbornene; for the remaining complexes, the cis-[L-Pd(PH(3))(2)Cl](+) isomer is substantially lower in energy. For cis-[L-Pd (PH(3))(2)Cl](+) complexes, the Pd-L bond energies are 28 kcal/mol for CO; ∼40 kcal/mol for AH(3) (A = N, P, As, and Sb), norbornene, and CH(3)CN; and ∼53 kcal/mol for CH(3)NC, pyrazole, pyridine, and tetrahydrothiophene at the CCSD(T) level. When Pd forms a donor-acceptor bond with the C atom in the ligand (i.e., CO, CH(3)NC, and the π-bond in norbornene), the Pd-L bond energies for trans-[L-Pd(PH(3))(2)Cl](+) are generally ∼10 kcal/mol greater than those for cis-[L-Pd(PH(3))(2)Cl](+) with the same L; for the remaining ligands, the ligand bond energy increases are ∼3-5 kcal/mol from the cis-isomer to the trans-isomer. The benchmarks show that the dispersion-corrected hybrid, generalized gradient approximation, DFT functional ω-B97X-D is the best one to use for this system. Use of the ω-B97X-D/aD functional gives predicted BDEs within 1 kcal/mol of the CCSD(T)/aug-cc-pVTZ BDEs for cis-[L-Pd(PH(3))(2)Cl](+) and 1.5 kcal/mol for trans-[L-Pd(PH(3))(2)Cl](+).

Dichlorido(η6-p-cymene)(4-fluoro­aniline-κN)ruthenium(II)

The title compound, [RuCl2(C10H14)(C6H6FN)], a pseudo-octahedral d 6 complex, has the expected piano-stool geometry around the Ru(II) atom. The fluoroaniline ring forms a dihedral angle of 19.3 (2)° with the p-cymene ring. In the crystal, two molecules form an inversion dimer via a pair of N—H⋯Cl hydrogen bonds. Weak intermolecular C—H⋯Cl interactions involving the p-cymene ring consolidate the crystal packing.

{2,6-Bis[(2,6-diisopropyl­phosphan­yl)­oxy]-4-fluoro­phenyl-κ3P,C1,P′}(1H-pyrazole-κN2)nickel(II) hexa­fluoro­phosphate

The title compound, [Ni(C18H30FO2P2)(C3H4N2)]PF6, was prepared by halide abstraction with TlPF6 in the presence of CH3CN in CDCl3 from the respective neutral pincer chlorido analogue followed by addition of pyrazole. The PO—C—OP pincer ligand acts in typical trans-P2 tridentate fashion to generate a distorted square-planar nickel structure. The Ni—N(pyrazole) distance is 1.925 (2) Å and the plane of the pyrazole ligand is rotated 56.2 (1)° relative to the approximate square plane surrounding the NiII center in which the pyrazole is bound to the NiII atom through its sp 2-hybridized N atom. This Ni—N distance is similar to bond lengths in the other reported NiII pincer-ligand square-planar pyrazole complex structures; however, its dihedral angle is significantly larger than any of those for the latter set of pyrazole complexes.

{2,6-Bis[(2,6-diphenyl-phosphan-yl)-oxy]-4-fluoro-phenyl-κP,C,P'}(6-methyl-2,2,4-trioxo-3,4-dihydro-1,2,3-oxathia-zin-3-ido-κN)palladium(II).

The title acesulfamate complex, [Pd(C30H22FO2P2)(C4H4NO4S)], contains a four-coordinate Pd(II) ion with the expected, although relatively distorted, square-planar geometry where the four L—Pd—L angles range from 79.58 (8) to 102.47 (7)°. The acesulfamate ligand is N-bound to Pd [Pd—N = 2.127 (2) Å] with a dihedral angle of 76.35 (6)° relative to the square plane. Relatively long phenyl–acesulfamate C—H⋯O and phenyl–fluorine C—H⋯F interactions consolidate the crystal packing.

Chlorido{2-[(dimethyl-amino)-methyl]phenyl-κC,N}(1-methyl-1H-imidazole-κN)palladium(II).

In the title compound, [Pd(C9H12N)Cl(C4H6N2)], which was synthesized from the reaction of 1-methylimidazole with dimeric dichloridobis[2-(dimethylamino)benzyl]palladium(II), the ring-deprotonated N,N-dimethylbenzylamine ligand acts in a C,N-bidentate fashion. The dihedral angle between the ring of the 1-methylimidazole ligand and the palladacycle plane is 57.88 (16)°. The two N atoms from the N,N-dimethylbenzylamine and 1-methylimidazole ligands are trans coordinated to the PdII atom.

Experiments in Thermodynamics and Kinetics of Phosphine Substitution in (p-Cymene)RuCl2(PR3).

This manuscript describes a set of three experiments that investigates the thermodynamic and kinetic aspects of phosphine substitution at a Ru center. In the first experiment, the students synthesize a Ru organometallic complex containing a phosphine ligand. In the second, equilibria for phosphine substitution involving several different phosphines are studied. The equilibrium constants are converted into free energies of reactions which are compared with data from literature thermochemical studies. In the third experiment, the kinetics of the substitution of tris(p-fluorophenyl)phosphine is studied using variable-temperature (25�60 °C range) 19F NMR. The kinetic studies confirm that this reaction follows a simple first-order rate law. With some approximations, combining the data obtained here and the literature thermochemical data allow estimation of the strength of a bridging Ru�Cl bond in the starting material used in this laboratory set. The materials used in these experiments are relatively inexpensive and air-stable.