Selenoether macrocyclic chemistry–syntheses and ligand properties of new small-ring Se3- and Se2N-donor macrocycles

Abstract

Simultaneous dropwise addition of thf/EtOH solutions of Se{(CH(2))(3)OTs}(2) and o-C(6)H(4)(CH(2)SeCN)(2) or NCSe(CH(2))(3)SeCN to a suspension of NaBH(4) in thf/EtOH at room temperature yields gram quantities of the 13- and 12-membered triselenoether macrocycles (1) and (2) respectively in high yield. The 11-membered ring (3) is obtained similarly by simultaneous dropwise addition of thf/EtOH solutions of Na(2)[o-C(6)H(4)Se(2)] (itself prepared by NaBH(4) reduction of the polymeric [o-C(6)H(4)Se(2)](n)) and Se{(CH(2))(3)OTs}(2) to a suspension of NaBH(4) in thf/EtOH. The small-ring, potentially tridentate Se(2)N(pyridyl)-donor macrocycles (4) and (5) were obtained in essentially quantitative yield by simultaneous dropwise addition of thf/EtOH solutions of 2,6-bis(bromomethyl)pyridine and either o-C(6)H(4)(CH(2)SeCN)(2) or NCSe(CH(2))(3)SeCN to a suspension of NaBH(4) in thf/EtOH at room temperature. (1)-(5) have been characterised by (1)H, (13)C{(1)H} and (77)Se{(1)H} NMR spectroscopy, EI MS, and for (1) and (4), by X-ray crystal structures. Reaction of PtMe(3)I with one mol. equiv. of L (L = (1)-(5)) in refluxing CHCl(3) gives the ionic complexes [PtMe(3)(L)]I cleanly and in good yield. These were characterised by (1)H, (13)C{(1)H}, (77)Se{(1)H} and (195)Pt NMR spectroscopy, electrospray MS, microanalyses and by crystal structures of [PtMe(3)((1))]I and [PtMe(3)((4))]I, which confirm distorted octahedral coordination at Pt(IV), with fac-tridentate coordination of the macrocycle in all cases, with anionic iodide. The complexes [PtCl(2)(L)] (L = (1)-(3)) were obtained as poorly soluble yellow-orange solids by reaction of PtCl(2) with L in MeCN solution. The d(3) Cr(III) complexes of L (L = (1)-(5)) were obtained by reaction with [CrCl(3)(thf)(3)] in anhydrous CH(2)Cl(2) as distorted octahedral fac-[CrCl(3)(L)], as poorly soluble blue-purple through to green powdered solids, which have been characterised by microanalysis, UV-visible and IR spectroscopy and by their magnetic moments. The properties of these complexes are compared with related chalcogenoether complexes from the literature involving thioether and acyclic selenoether coordination.