Coordination chemistry of H‐spirophosphorane ligands towards pentacarbonylchlororhenium(I) – synthesis, structure and catalytic activity of complexes

Abstract

Synthesis of a group of carbonyl rhenium coordination compounds with hydrospirophosphorane ligands was carried out and described. Different symmetrical HP(OCH2CH2NH)2L1, HP(OCH2CMe2NH)2L2, HP(OC6H4NH)2L3, and unsymmetrical ligands HP (OCMe2CMe2O)(OC6H4NH) L4 were found to coordinate to the rhenium center as bidentate P,N donor ligands yielding fac‐[ReCl (CO)3Ln], where n = 1–4. Furthermore, monodentate coordination was also observed in some cases, as was clearly presented in the case of [ReCl(CO)2(L4‐κ2P,N)(L4‐κP)] complex. All of the complexes were characterized using optical spectroscopy. Single‐crystalX‐ray diffraction was also performed in the case of fac‐[ReCl(CO)3L3], fac‐[ReCl(CO)3L4], [Re(CO)2(L2)2]Cl and [ReCl (CO)2(L4‐κ2P,N)(L4‐κP)] samples. Complexes [ReCl(CO)3L3] and [ReCl (CO)3L4], both bearing rings of conjugated double bonds within hydrospirophosphorane ligands, exhibited luminescence. Catalytic properties of rhenium complexes were assessed using the representative fac‐[ReCl (CO)3L2] complex in the dimerization reaction of terminal alkynes. An efficient and selective procedure for synthesis of the E‐enynes was developed. Coupling of (2‐chlorophenyl)acetylene was mediated by [ReCl (CO)3L2]/TBAF system with a 100% conversion rate. Different substituents within aromatic alkynes were tolerated and the resulting products were dependent on the nature of the substituents.