Syntheses of Pd(ii)/Pt(ii) complexes with non-chelating 4-pyridylselenolate ligand ranging from mononuclear to macrocyclic structures and their utility as catalysts in Suzuki C–C coupling reaction†
Abstract
Treatment of Na2PdCl4 or [MCl2(PhCN)2] with bis(4-pyridyl)diselenide yielded an insoluble product of composition [MCl2(4,4′-(C5H4N)2Se2)]n (1). The reactions of Na2PdCl4 with one and two eq. of Na(4-SeC5H4N) afforded insoluble products [PdCl(4-SeC5H4N)]n (2) and [Pd(4-SeC5H4N)2]n (3), respectively. On treatment with PPh3, 2 and 3 gave trans-[PdCl(4-SeC5H4N)(PPh3)2] (4a) and trans-[Pd(4-SeC5H4N)2(PPh3)2] (5a), respectively. The oxidative addition of bis(4-pyridyl)diselenide to Pt(PPh3)4 exclusively yielded trans-[Pt(4-SeC5H4N)2(PPh3)2] (5b). The treatment of two eq. of Na(4-SeC5H4N) with cis-[PtX2(PR3)2] afforded 5b (X = Cl) and trans-[Pt(4-SeC5H4N)2(PEt3)2] (5c) (X = Cl or CF3SO3). The reactions of cis-[MCl2(P∩P)] and [M2Cl2(μ-Cl)2(PR3)2] with two eq. of Na(4-SeC5H4N) exclusively yielded cis-[M(4-SeC5H4N)2(P∩P)] (M/P∩P = Pd/