Bruce N. Storhoff

Addition of diphenylphosphine to Michael-type olefins: the preparation of phosphine-nitrile and phosphine-ester ligands

Abstract The reactions of five Michael-type olefins with diphenylphosphine have been carried out. 1-Cyanocyclopentene, 1-cyanocyclohexene, and 4-t-butyl-1-cyanocyclohexene all provide the corresponding 2-diphenylphosphino-1-cyanocycloalkanes, and both methyl acrylate and ethyl methacrylate yield the corresponding 2-diphenylphosphinopropionates. For the products from 1-cyanocyclopentene and 1-cyanocyclohexene, 13C and 31P NMR data are consistent with the formation of both trans (Ph2P equatorial and CN axial) and cis (both Ph2P and CN equatorial) isomers. The morpholine amide of 3-diphenylphosphinopropionic acid has been obtained by treatment of methyl-3-diphenylphosphinopropionate with the dimethylaluminum adduct of morpholine. This phosphine, Ph2Pmorph, has been isolated as its palladium(II) complex, (Ph2Pmorph)2PdCl2. A phosphine-benzaldimine, Ph2P(CH2)3NC(H)C6H5, has been obtained by reacting Ph2P(CH2)3NH2, from the reduction of PhP(CH2)2CN, with benzaldehyde in the presence of molecular sieves.

Rhenium(I) complexes of (2-cyanoethyl)diphenylphosphine

Abstract Rhenium pentacarbonyl halides react with (2-cyanoethyl) diphenylphosphine (L) to yield complexes of the stoichiometry [Re(CO) 3 LX] n . The infrared spectra of the complexes are consistent with structures containing terminal halogens and bridging L groups. Molecular weight studies indicate that n is two for solutions of 10 −3 M . The nitrile portion of the ligand is readily displaced by σ donor ligands to yield complexes in which L functions as a monodentate phosphine.

The synthesis of some bidentate ligands containing both phosphine and nitrile groups

Abstract Both (C6H5)2P(CH2)3CN and (C6H5)2P(CH2)4CN have been obtained from the reaction of Br(CH2)nCN (n = 3, 4) with (C6H5)2POCH3 followed by reduction with (C6H5)2SiH2. These phosphine-nitrile ligands form L2PdCl2 complexes which are shown by IR measurements to have trans geometries with the phosphine portions of the ligands coordinated. Reactions of o-BrC6H4CN with CH3(CH2)3Li followed by R2PCl (R = C6H5 or (CH3)2N) have been used to provide good yields of the corresponding R2P-o-C6H4CN products.

SYNTHESIS AND STUDY OF PHOSPHINES INCORPORATING 2-CYANOPHENYL GROUPS AND THE X-RAY STRUCTURE OF TRIS(2-CYANOPHENYL)PHOSPHINE

Abstract Both PhP(2-NCC6H4)2 and P(2-NCC6H4)3 have been synthesized from the carbanions generated from 2-bromobenzonitrile and dimethyl phenylphosphonite or triphenyl phosphite. The A1 υ(CO) bands for the Ni(CO)3L complexes of these two ligands along with that from the previously reported Ph2P(2-NCC6H4) have been recorded in dichloromethane solutions. The values (2073.0, 2076.4 and 2079.7 cm−1; decreasing number of Ph rings) reflect the electron-withdrawing nature of the ortho-positioned cyano groups. 31P chemical shifts of the L2PdCl2 complexes of these three ligands have been recorded, and all provide shifts of δ=24.1±1, approximately that for (PPh3)2PdCl2, δ=23.9. The molecular structure of P(2-NCC6H4)3, from X-ray crystallographic studies, is reported. A prominent feature of the structure is that the cyano groups are pointed in the general direction of the phosphorus lone pair. The average distances from phosphorus to cyano carbon and nitrogen atoms were found to be 3.03 and 3.23 A, respectively.

Organophosphorus molecules of the stoichiometry B9H11CPR

Abstract The reaction of 7,8- or 7,9- B9H11CP− with alkyl halides (RX) resulted in molecules of the stoichiometry B9H11CPR. NMR spectra of the products are reported and these data indicate that the R groups are bonded to tile phosphorus.

Tetrahydrofuran Complexes of Rhenium(I)

Abstract Dimeric tetrahydrofuran complexes of rhenium(I) can be synthesized in good yields directly from Re(CO)5 X (X [dbnd] Cl, Br) and tetrahydrofuran. These complexes, [Re(CO)3(THF)X]2, are convenient precursors for the preparation of small amounts of the tricarbonyl complexes fac-Re(CO)3L2X.

HYBRID PHOSPHINE-CROWN ETHER LIGANDS: THE STUDY OF BENZO-15-CROWN-5 AND N-PHENYLAZA-15-CROWN-5 AND -18-CROWN-6 FUNCTIONALIZED WITH Ph2P-

Abstract Methods for the preparation of the 4-diphenylphosphino derivatives of N-phenylaza-15-crown-5 and -18-crown-6 are described. The properties of these systems and the 4′-diphenylphosphino derivative of benzo-15-crown-5 have been examined by way of picrate ion extraction abilities and IR spectra of their Ni(CO)3L (L = these phosphines) complexes. All three have abilities to extract Na+ and K+ that are comparable to benzo-15-crown-5. The IR studies (νCO, A1 band) indicate that the azacrown systems have better ability than the benzocrown system to increase the electron density on the nickel center. Further, the addition of alkali metal ions, Na+ and K+, to the Ni(CO)3L solutions results in maximum shifts of ca 1.5 cm−1 for the former systems and 0.7 cm−1 for the latter system. A rationale for this observation is presented in terms of Hammett substituent constants. Finally, an X-ray structure of the phosphine oxide of the phenylaza-15-crown-5 derivative is presented. A prominent feature of the structure...

Steric effects of phosphorus ligands: cis/trans distributions of W(CO)4L2 products

Abstract The cis/trans product distribution in the reaction of phosphines with W(CO)4(Me2N(CH2)3NMe2 depends on ligand size; the smaller the ligand the greater the cis/trans ratio. The ratios range from 2.9 to 0 for PPh2Me and P(o-Tol)3, respectively.

4′ DIPHENYLPHOSPHINO AND BROMO DERIVATIVES OF 10-PHENYL-1,4,7-TRITHIA-10-AZA-CYCLODODECANE 4-R- C6H4N(CH2CH2S)2CH2CH2SCH2CH2

Abstract 4-Br-C6H4N(CH2CH2S)2CH2CH2SCH2SCH2CH2 and 4-Ph2P-C6H4N(CH2CH2S) 2CH2CH2SCH2CH2 have been synthesized and characterized. The former cyclododcane has been obtained from the reaction between 4-BrC6H4N(CH2CH2Cl)2 and S(CH2CH2SH)2 in N,N-dimethylformamide containing Cs2CO3. The latter has been obtained from the former by way of a low temperature lithium-bromine exchange reaction (butyllithium) that provided the carbanion which was subsequently reacted with chlorodiphenylphosphine. In regard to characterization, X-ray methods have been used to study the former (P21, a = 8.356(3) A, b = 12.325(5) A, c = 16.012 (7). β = 100.81, Z = 4), and two crystallographically independent molecules were found. In both molecules, the nitrogen atoms are nearly planar with short N-C(sp2) bond lengths, and, second, the sulfur atoms are in exodenate positions. For the phosphine, a 31P signal was observed at -7.1 ppm, and this peak position was considered to be indicative of a structure involving a planar nitrogen atom.

AN IMPROVED SYNTHETIC METHOD FOR DIPHENYL-1-PYRENYLPHOSPHINE AND THE PROPERTIES AND STRUCTURE OF ITS BORANE ADDUCT

An efficient synthetic method for diphenyl-1-pyrenylphosphine, DPPP, has been developed involving a low temperature Li-Br exchange reaction using the commercially available 1-bromopyrene. An estimate of the donor ability of this phosphine has been obtained by measuring the A1υ (CO) band of the Ni(CO)3L complex which was found to be 0.4 wave numbers lower than that from the PPh3 complex indicating that DPPP is a slightly better donor than PPh3. The BH3 adduct of DPPP has been prepared and, as the situation for the oxide of DPPP, this adduct is fluorescent. It is estimated that the fluorescence intensity is about half that of DPPPO. An x-ray structure of this adduct has been obtained, and the bond lengths and angles appear to be in expected ranges.