117119-84-3Relevant academic research and scientific papers
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.
