From metal imides and molecular nitrogen to ammonia and dinitrogen complexes
作者:Modher Y. Mohammed、Christopher J. Pickett
DOI:10.1039/c39880001119
日期:——
Reduction of a molybdenum imide under molecularnitrogen gives ammonia and a dinitrogencomplex.
在分子氮下还原钼酰亚胺得到氨和二氮配合物。
Electrosynthesis of amino acids from a molybdenum nitride via nitrogen–carbon and carbon–carbon bond formation reactions involving imides and nitrogen ylides: X-ray structure of trans-[MoCl(NCHCO<sub>2</sub>Me)(Ph<sub>2</sub>PCH<sub>2</sub>CH<sub>2</sub>PPh<sub>2</sub>)<sub>2</sub>]·CH<sub>2</sub>Cl<sub>2</sub>
作者:David L. Hughes、Saad K. Ibrahim、Colin J. Macdonald、Hapipah Mohd. Ali、Christopher J. Pickett
DOI:10.1039/c39920001762
日期:——
Sequential nitrogenâcarbon and carbonâcarbon bond formation, and an electrochemical MoâN bond cleavage step, define a pathway to methyl esters of the amino acids glycine and alanine from the molybdenum nitride trans-[MoCl(N)(Ph2PCH2CH2PPh2)2], a key intermediate being the metallo-nitrogen ylide trans-[MoCl(NCHCO2Me)(Ph2PCH2CH2PPh2)2], the structure of which has been determined crystallographically.
Mechanism of ammonia formation by reaction of trans-[Mo(NH)X(Ph2PCH2CH2PPh2)2]+(X = F, Cl, Br, or I) with base in methanol
作者:Richard A. Henderson、Geoffrey Davies、Jonathan R. Dilworth、Roger N. F. Thorneley
DOI:10.1039/dt9810000040
日期:——
of [MoN(dppe)2]+ and X–. This cation reacts with methoxide ion (k= 1.7 ± 0.4 × 106 dm3 mol–1s–1), to yield [MoN(OCH3)(dppe)2] which rapidly abstracts a proton from solvent to give [Mo(NH)(OCH3)(dppe)2]+. When X = F, the same sequence of reactions occurs but dissociation of fluoride from the intermediate [Mo(N)F(dppe)2] is rate-limiting (k= 1.78 s–1). The pKa of trans-[Mo (NH)X(dppe)2]+ is very sensitive
Ligand-centred chemistry of molybdenum organoimides. Formation of C–C bonds via generation of nitrogen ylides, stereospecific conversion of an allylimide into alkylvinyl-imides, liberation of cyanoformate or amino acid esters
作者:Shirley A. Fairhurst、David L. Hughes、Saad K. Ibrahim、Marie-Laurence Abasq、Jean Talarmin、M. Arlete Queiros、Antonio Fonseca、Christopher J. Pickett
DOI:10.1039/dt9950001973
日期:——
The range of imides trans-[MoCl(NCHR(1)R(2))(dppe)(2)](+) made from the nitride trans-[MoCl(N)(dppe)(2)] (dppe = Ph(2)PCH(2)CH(2)PPh(2), R(1) = H or organic group, R(2) = organic group) has been extended; deprotonation of the imide group at the alpha-carbon gives reactive alkenylamides which have nitrogen ylide character Mo=N+-C(-)HR} and these are attacked by electrophiles. Stepwise C-1 homologation of a methylimide to ethyl- and isopropyl-imides can be achieved by successive deprotonation and methylation steps. The crystal structure of the alkenylamide trans-[MoCl(NCHCO(2)Me)(dppe)(2)] has been determined, as has that of the imide produced directly from it by C-methylation, trans [MoClNCH(Me)CO(2)Me}(dppe)(2)](+). Deprotonation at the alpha-carbon of an allylimide complex gives a species which is regioselectively and stereospecifically attacked by electrophiles at the gamma-carbon; when the electrophile is the proton the overall reaction corresponds to a 1,3-prototropic rearrangement of the allylimide to the E-methylvinylimide. Electroreduction of imides in the presence of a source of protons releases the free amine; in this way esters of the amino acids glycine and DL-alanine have been:synthesised. Two protons-can be removed by base from imides with electron-withdrawing ester substituents and free cyanoformate esters are released from-the metal centre by substitution with dinitrogen or CO.
Alias, Yatimah; Ibrahim, Saad K.; Queiros, M. Arlete, Journal of the Chemical Society, Dalton Transactions
作者:Alias, Yatimah、Ibrahim, Saad K.、Queiros, M. Arlete、Fonseca, Antonio、Talarmin, Jean、et al.