{2,6-Bis[(2,6-diisopropyl-phosphan-yl)-oxy]-4-fluoro-phenyl-κ(3)P,C(1),P'}(1H-pyrazole-κN(2))nickel(II) hexa-fluoro-phosphate.

The title compound, [Ni(C(18)H(30)FO(2)P(2))(C(3)H(4)N(2))]PF(6), was prepared by halide abstraction with TlPF(6) in the presence of CH(3)CN in CDCl(3) from the respective neutral pincer chlorido analogue followed by addition of pyrazole. The PO-C-OP pincer ligand acts in typical trans-P(2) tridentate fashion to generate a distorted square-planar nickel structure. The Ni-N(pyrazole) distance is 1.925 (2) Šand the plane of the pyrazole ligand is rotated 56.2 (1)° relative to the approximate square plane surrounding the Ni(II) center in which the pyrazole is bound to the Ni(II) atom through its sp(2)-hybridized N atom. This Ni-N distance is similar to bond lengths in the other reported Ni(II) 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(C(30)H(22)FO(2)P(2))(C(4)H(4)NO(4)S)], 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 phen-yl-acesulfamate C-H⋯O and phen-yl-fluorine C-H⋯F inter-actions consolidate the crystal packing.

Dichlorido(η-p-cymene)(4-fluoro-aniline-κN)ruthenium(II).

The title compound, [RuCl(2)(C(10)H(14))(C(6)H(6)FN)], a pseudo-octa-hedral d(6) complex, has the expected piano-stool geometry around the Ru(II) atom. The fluoro-aniline ring forms a dihedral angle of 19.3 (2)° with the p-cymene ring. In the crystal, two mol-ecules form an inversion dimer via a pair of N-H⋯Cl hydrogen bonds. Weak inter-molecular C-H⋯Cl inter-actions involving the p-cymene ring consolidate the crystal packing.

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

In the title compound, [Pd(C(9)H(12)N)Cl(C(4)H(6)N(2))], which was synthesized from the reaction of 1-methyl-imidazole with dimeric dichloridobis[2-(dimethyl-amino)-benz-yl]palla-dium(II), the ring-deprotonated N,N-dimethyl-benzyl-amine ligand acts in a C,N-bidentate fashion. The dihedral angle between the ring of the 1-methyl-imidazole ligand and the palladacycle plane is 57.88 (16)°. The two N atoms from the N,N-dimethyl-benzyl-amine and 1-methyl-imidazole ligands are trans coordinated to the Pd(II) atom.

Sweet success: Ionic liquids derived from non-nutritive sweeteners.

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

A priori assessment of the stereoelectronic profile of phosphines and phosphites.

This research has demonstrated the utility of a rigorously calibrated, molecular mechanics/semiempirical quantum mechanical protocol for developing stereoelectronic (Tolman) maps for phosphine ligands. A computational analysis of alkyl and aryl phosphines in common usage suggests that these ligands are quite similar stereoelectronically. A noticeable gap in the Tolman map for common phosphines is observed for large, electron-poor phosphines. Several candidates meeting these criteria were identified, the most promising of which is P(t-C(4)F(9))(3). Phosphines in which the phosphorus participates in a ring, which comprise a very small subset of reported phosphines, have very interesting stereoelectronic properties, particularly those in which the ligating phosphorus is part of a three-membered ring. In terms of steric properties, the symmetric deformation coordinate proposed by Orpen and co-workers on the basis of crystallographic studies is calculated with sufficient accuracy using PM3(tm) to allow good confidence in predictions of novel phosphines. For quantification of the electronic properties of phosphines, we analyzed changes in the CO stretching frequency upon changing the ancillary phosphine ligands.