화학공학소재연구정보센터
Journal of the American Chemical Society, Vol.117, No.19, 5303-5311, 1995
Tetraalkylammonium Salts as Stereospecific Alkylating-Agents for Highly Nucleophilic Polyphosphide Zintl Anions - Preparation of (RP(7)W(Co)(3))(2-), (R(2)P(7))(-), and R(2)R’p-7 Compounds from R(4)N(+) Reagents
[K(2,2,2-ctypt)](3) [P7W(CO)(3)] reacts with R(4)N(+) salts (R = Me, Et, n-Bu) in ethylenediamine (en) or dimethylformamide (DMF) solutions to give the [RP(7)W(CO)(3)](2-) ions (4) and R(3)N in high yields. Similar reactions involving Me(n-C8H17N+ and (CH(2)Ph)Me(3)N(+) give the [MeP(7)W(CO)(3)](2-) and [(CH(2)Ph)P7W(CO)(3)](2-) ions, respectively. Reactions of [HP7W(CO)(3)](2-) with olefins did not affect insertions into the P-H bond to give compounds 4. These data indicate that the alkylations proceed by way of nucleophilic attack at the alpha-carbon of the tetraalkylammonium ions and not by a radical electron transfer pathway or a Hofmann elimination/olefin insertion pathway. Compounds 4 were characterized by H-1, C-13, and P-31 NMR and IR spectroscopic studies, microanalyses, and representative crystallographic studies. They possess C-1 symmetry in the solid state but display C-s symmetry in solution due to an intramolecular wagging process. The P-31{H-1} NMR spectra for 4 reveal an AA’BB’MM’X spin system.Crystal data for [K(2,2,2-crypt)](2)[EtP(7)W(CO)(3)]. en: triclinic, space group P ($) over bar 1, a = 12.176(3) Angstrom, b = 15.106(2) Angstrom, c = 18.975(2) Angstrom, alpha = 93.509(10)degrees, beta = 98.833(13)degrees, gamma = 111.472(12)degrees, V = 3183.1(9) Angstrom(3), Z = 2; R(F) = 4.29% and R(w)(F-2) = 10.34%. The P-7(3-) ion reacts with excess R(4)N(+) (R = Me, Et, n-Bu) in en or DMF solutions to give symmetrical [R(2)P(7)](-) ions (5) in quantitative yields. The reactions are stereospecific in that only one of three possible isomers is formed in each case. Compounds 5 have been characterized by H-1, C-13 and P-31 and 2-D P-31-P-31 COSY NMR spectroscopic studies. Compounds 5 react with alkyl halides, R’X where R’= CH(2)Ph, X = Cl; R’ = Me, X = I; R’ = n-Bu, X = Br to give mixtures of the symmetric and asymmetric isomers (similar to 1:10 ratios) of R(2)R’P-7 compounds (6). The symmetric and asymmetric isomers are formed competitively from compounds 5 and do not interconvert in solution. Spectroscopic studies on the formation of the (n-Bu)(3)P-7 compound (6e) show virtually quantitative "one pot" syntheses of compounds 6 from the P-7(3-) parent ion but studies of the other members of compounds 6 were hampered by their low solubilities. Ah compounds 6 are thermally unstable to some extent with the sterically hindered compounds being somewhat more robust than their less hindered analogs. They have been characterized by P-31 NMR spectroscopy and FAB-MS (M + 1 molecular ions).