Synthesis of Rhenium Complexes That Contain the [(C<sub>6</sub>F<sub>5</sub>NCH<sub>2</sub>CH<sub>2</sub>)<sub>3</sub>N]<sup>3-</sup> Ligand

The reaction between [Et<sub>4</sub>N]<sub>2</sub>[ReOCl<sub>5</sub>] and (C<sub>6</sub>F<sub>5</sub>NHCH<sub>2</sub>CH<sub>2</sub>)<sub>3</sub>N (H<sub>3</sub>[N<sub>3</sub>N<sub>F</sub>]) in CH<sub>3</sub>CN at room temperature in the presence of NEt<sub>3</sub> yielded air stable, emerald green, diamagnetic [(C<sub>6</sub>F<sub>5</sub>NCH<sub>2</sub>CH<sub>2</sub>)<sub>2</sub>NCH<sub>2</sub>CH<sub>2</sub>NHC<sub>6</sub>F<sub>5</sub>]Re(O)Cl (<b>1</b>). The reaction between <b>1</b> and Ta(CH-t-Bu)(THF)<sub>2</sub>Br<sub>3</sub> gave paramagnetic [N<sub>3</sub>N<sub>F</sub>]ReBr (<b>2</b>). An X-ray structure of a sample of <b>2</b> showed it to be analogous to that of [N<sub>3</sub>N<sub>F</sub>]MoCl. Reduction of <b>2</b> by methyllithium (or more conveniently by Mg) in the presence of a variety of two-electron ligands gave complexes of the type [N<sub>3</sub>N<sub>F</sub>]Re(L) (L = H<sub>2</sub>, ethylene, propylene, CO, N<sub>2</sub>, phosphines, pyridine, tetrahydrothiophene, acetonitrile, or silanes). An X-ray structure of [N<sub>3</sub>N<sub>F</sub>]Re(ethylene) showed η<sup>2</sup>-ethylene to be bound in the apical “pocket” with its C−C axis lying in one of the N<sub>ax</sub>−Re−N<sub>eq</sub> planes. Protonation of the PMe<sub>3</sub> complex gave an authentic hydrido phosphine complex, {[N<sub>3</sub>N<sub>F</sub>]Re(H)(PMe<sub>3</sub>)}<sup>+</sup>, but protonation of other phosphine complexes gave species in which coupling between H and P is relatively large (∼60 Hz) and therefore that are believed to have some {[N<sub>3</sub>N<sub>F</sub>]Re(η<sup>2</sup>-HPR<i><sub>x</sub></i>H<sub>3</sub><sub>-</sub><i><sub>x</sub></i>)}<sup>+</sup> character. An X-ray study of {[N<sub>3</sub>N<sub>F</sub>]Re(H)(PHPh<sub>2</sub>)}<sup>+</sup> confirmed that one proton is terminally bound to phosphorus and that the phosphorus is “off-axis” in order to accommodate the “hydride” in the same plane.