The synthesis and structure of potassium cyanotrimethylaluminate

The reaction of KCN with Al(CH₃)₃ to form K[Al(CH₃)₃CN] is greatly facilitated by the presence of an aromatic solvent: for p-xylene a solid complex, K[Al(CH₃)₃CN]·C₆H₄(CH₃)₂, has been isolated. The crystal structure of potassium cyanotrimethylaluminate has been determined from three-dimensional X-ray data measured by counter methods. K[Al(CH₃)₃CN] crystallizes in the monoclinic space group C2/c with cell dimensions a = 19.902(7), b = 9.211(4), c = 9.615(4) Å, β = 107.74(5)°, and p_calcd. = 1.09 g cm^?1 for Z = 8. Least squares refinement gave a conventional weighted R factor of 4.9% for 807 independent reflections. The monomeric [Al(CH₃)₃CN]^? units possess no crystallographic symmetry, and the packing in the unit cell is such that the nitrogen atoms on three such units approach the potassium atom to within 3.11 Å. The average aluminum-methyl carbon bond distance is 1.971 (7) Å, while the aluminum-cyano carbon distance is 2.047 (7) Å. This significant lengthening is attributed to partial electron deficiency in the aluminum-cyano carbon bond.     

The 53rd New England Association of Chemistry Teachers Summer Conference. A model for our division

An outline of the 53rd New England Association of Chemistry Teachers Summer Conference is given along with a detailed listing of the conference participants and the lectures presented. Then it is proposed that the Division of Nuclear Chemistry and Technology of the American Chemical Society host similar conferences around the country to influence high school teachers in their teaching of nuclear science.     

Preparation and properties of dinitrogen complexes of molybdenum and tungsten with trimethylphosphine as coligand : III. Synthesis and properties of cis-[W(N2)2(PMe3)4], trans-[W(C2H4)2(PMe3)4] and [M(N2)(PMe3)5] (M = Mo,W). The crystal and molecular structure of [Mo(N2)(PMe3)5]

The reduction of [WCl₄(PMe₃)₃] with dispersed sodium, under dinitrogen, gives cis-[W(N₂)₂(PMe₃)₄], while under ethylene trans-[W(C₂H₄)₂(PMe₃)₄] is obtained. The ethylene complex can also be prepared by displacement of the dinitrogen molecules in cis-[W(N₂)₂(PMe₃)₄] by ethylene at room temperature and pressure. Interaction of cis-[M(N₂)₂(PMe₃)₄] complexes (M = Mo, W), with PMe₃, under helium or argon, yields [M(N₂)(PMe₃)₅]. The molybdenum complex crystallizes in the orthorhombic space group Pnma, with a 22.063(6), b 12.106(4), c 9.745(4) Å. The Mo—P distance trans to the dinitrogen ligand (2.483(7) Å) is slightly longer than the average of the other four Mo—P bonds (2.460(5) Å).     

Anion-sealed single-molecule capsules

A new approach to anion recognition utilizing electrostatic and hydrogen bonding interactions has been demonstrated by placement of the whole ion-pair in a molecular capsule.     

(Z)-3-p-tolylsulfinylacrylonitrile as a chiral dienophile: diels-alder reactions with furan and acyclic dienes

The behavior of (Z)-3-p-tolylsulfinylacrylonitrile (1) as a chiral dienophile has been evaluated from its reactions with furan and acyclic dienes. Electrostatic interactions of the cyano group with the sulfinyl one restrict the conformational mobility around the C-S bond, thus controlling the pi-facial selectivity, which is almost complete in all cases, the approach of the diene from the less-hindered face of the dienophile (that bearing the lone electron pair) in the predominant rotamer being the favored one. The regioselectivity is also completely controlled by the cyano group. Additionally, the reactivity of compound 1 as well as its endo-selectivity are both higher than those observed for the corresponding (Z)-3-sulfinylacrylates, thus proving the potential of sulfinylnitriles as chiral dienophiles.     

Synthesis and X-ray crystal structure of a five-coordinate d8 complex: [Pt((Me2NN)(PMe2)(PPh2))2Cl][Cl]

C₃₆H₅₀Cl₂N₆P₄Pt·2 MeCN,2, triclinic P¯1,a=11.720(2),b=12.153(2),c=16.196(3),=76.74(1),=84.90(1),=88.13(1),Z=2,R=0.051,Rw=0.051. Interaction of Me₂NN(PMe₂)(PPh₂),1, with Pt(COD)Cl₂, COD=1,5 cyclooctadiene, in THF yields the title compound,2, in quantitative yield. Compound2 was characterized spectroscopically as well as via an X-ray diffraction study.     

The interaction of aromatic hydrocarbons with organometallic compounds of the main group elements : III. The crystal structure of K[Al2(CH3)6F]·C6H6

The crystal structure of K[Al₂(CH₃)₆F]·C₆H₆ has been determined from three-dimensional X-ray data measured by counter methods. The compound crystallizes in the orthorhombic space group Pnma with cell dimensions a = 14.071(5), b = 14.404(5), c = 8.862(3) Å and ρ_calc = 1.04 g·cm^-3 for Z = 4. Least squares refinement gave a conventional weighted R factor of 0.037 for 973 independent observed reflections. In the fluorine-bridged anion, the aluminum—fluorine—aluminum bond angle is fixed at 180° by crystallographic symmetry. The aluminum—fluorine bond length of 1.782(2) Å is compared to other halogen-bridged systems. The potassium ion coordination sphere contains six methyl groups at distances from 3.23 to 3.47 Å; the benzene functions as a molecule of crystallization with 3.947(7) Å as the shortest benzene carbon—potassium ion approach.