Synthesis and characterization of some rhenium complexes with the new mixed phosphorus–nitrogen donor ligand NPh(CH2CH2PPh2)2

Abstract
Reaction of NPh(CH2CH2Cl)2 with LiPPh2 at 0 °C yields the new mixed nitrogen–phosphorus donor ligand NPh(CH2CH2PPh2)2(L). Reaction of [ReOCl3(AsPh3)2] with L in CH2Cl2 at room temperature gives [ReOCl3L]3. Reaction of [ReCl3(MeCN)(PPh3)2] with L in refluxing benzene gives [ReCl3L]4. Treatment of 3 or 4 with LiAlH4 at 0 °C in Et2O affords [ReH5L]5. Protonation of 5 with HBF4·OEt2 in CD2Cl2 at 193 K gives [ReH6L]+6. Deprotonation of 6 with NEt3 regenerates 5 quantitatively. Compound 5 shows a 1H NMR T1(minimum) value of 78 ms at 250 MHz, consistent with a classical structure having only terminal hydride ligands, while 6 shows a T1(minimum) value of 10 ms, suggesting a non-classical structure containing one or more η2-H2 ligands.

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