117120-00-0Relevant academic research and scientific papers
Geometrical isomers of neutral (pentamethylcyclopentadienyl)rheniuin complexes resulting from different orientations of a singly-bent aryldiazenido ligand
Garcia-Minsal, Ariana,Sutton, Derek
, p. 332 - 336 (1996)
The variable temperature 1H NMR spectra of Cp*ReH(CO)(p-N2C6H4OMe) (1) and Cp*Re-(CH3(CO)(p-N2C6H4OMe) (3) and the variable temperature 31P{1H} NMR spectra of Cp*ReCl-(PR3)(p-N2C6H4OMe) [R = Me (4), OMe (5), Ph (7)] are presented and discussed. The spectra of 1 and 3-5 show that at low temperature two isomers are present in each case and that these isomers interconvert on the NMR time scale. The isomers are interpreted to occur because the p-N2C6H4OMe ligand adopts two different orientations where the aryl group is oriented syn to either the X or Y ligand in these chiral complexes of general formula Cp*ReXY(p-N2C6H4OMe). The bulky PPh3 ligand in 7 results in an overwhelming preference for orientation only syn to the C1 group and thus only one observable isomer. The activation parameters for the conformational isomerization of the aryldiazenido ligand in these neutral complexes have been obtained from NMR line shape analyses and are compared with data obtained previously for related cationic rhenium aryldiazenido complexes.
Rhenium carbonyl phosphine dinitrogen complexes (η5-C5Me5)Re(CO)(PR3)(N 2)
Klahn, A. Hugo,Sutton, Derek
, p. 198 - 206 (2008/10/08)
The new rhenium dinitrogen complexes (η5-C5Me5)Re(CO)(PR3)(N 2) (3a-f) have been synthesized for PR3 = (a) PMe3, (b) P(n-Bu)3, (c) PCy3 (Cy = cyclohexyl), (d) PPh3, (e) P(OMe)3, and (f) P(OCH2)3CMe by treatment of the corresponding p-methoxyphenyldiazenido complexes [(η5-C5Me5)Re(CO)(PR3)(p-N 2C6H4OMe)][BF4] (2a-f) with t-BuLi. These cationic phosphine complexes 2a-f were synthesized from the cationic acetonitrile complex [(η5-C5Me5)Re(CO)(NCMe)(p-N 2C6H4OMe)][BF4] (1a) and the appropriate phosphine. The compounds have been characterized spectroscopically, including unambiguous 15N and 14N NMR assignments of the Nα and Nβ resonances of the aryldiazenide and dinitrogen ligands. Comparisons are made with the properties of the related known dicarbonyl compounds [(η5-C5Me5)Re(CO)2(p-N 2C6H4OMe)][BF4] and (η5-C5Me5)Re(CO)2(N 2). It is shown that the 15N label in 15Nα-labeled 2a and 2e is retained exclusively at the Nα position in the dinitrogen complexes 3a and 3e; however, an equimolar mixture of 15Nα- and 15Nβ-labeled (η5-C5Me5)Re(CO)2( 15N14N) results when this dinitrogen complex is synthesized from exclusively 15Nα-labeled [(η5-C5Me5)Re(CO)2(p- 15N14NC6H4OMe)][BF4]. Hexane or cyclohexane solution IR spectra of 3d (PR3 = PPh3) and 3e (PR3 = P(OMe)3), but not of the remainder, show two ν(NN) absorption bands. This is attributed to the existence of more than one possible conformation of the PR3 ligand in these complexes. The N2 ligand in 3a (PR3 = PMe3) is remarkably inert, as it is not displaced by PPh3 at room temperature in diethyl ether solution and shows no exchange with nitrogen gas when pressurized.
