Novel Trisphosphine Ligand Containing 1,3,5-Triazine Core, [2,4,6‑C3N3{C6H4PPh2‑p}3]: Synthesis and Transition Metal Chemistry

The trisphosphine ligand with triazine core, 2,4,6-tris­{4-(diphenylphosphino)­phenyl}-1,3,5-triazine (2), was synthesized in moderate yield by reacting 2,4,6-tris­(4-bromophenyl)-1,3,5-triazine with 3 equiv of KPPh2. The tris­(phosphine) 2 undergoes facile oxidation to give trischalcogenides 2,4,6-C3N3{C6H4P­(E)­Ph2-p}3 (E = O, 3; S, 4; Se, 5) on treatment with aqueous H2O2, elemental sulfur, or selenium. The reaction between 2 and [AuCl­(SMe2)] yielded a trinuclear complex, [(AuCl)3{2,4,6-C3N3(C6H4PPh2-p)3}] (6), which on further treatment with pyridyl ligands such as 2,2′-bipyridine (2,2′-bpy) and 1,10-phenanthroline (1,10-phen) produced the mixed-ligand complexes [{Au­(2,2′-bpy)}3{2,4,6-C3N3(C6H4PPh2-p)3}]­(OTf)3 (7) and [{Au­(1,10-phen)}3{2,4,6-C3N3(C6H4PPh2-p)3}]­(OTf)3 (8), where OTf indicates trifluoromethansulfonate. Several trimetallic complexes such as [{Ru­(η6-cymene)­Cl2}3{2,4,6-C3N3(C6H4PPh2-p)3}] (9), [{Pd­(η3-C3H5)­Cl}3{2,4,6-C3N3(C6H4PPh2-p)3}] (10), [{Rh­(COD)­Cl}3{2,4,6-C3N3(C6H4PPh2-p)3}] (11) and [{Ir­(COD)­Cl}3{2,4,6-C3N3(C6H4PPh2-p)3}] (12) have also been synthesized and characterized. The reactions of 2 with [M­(COD)­Cl2] and CuI afforded metallo-cyclophane type complexes, [(MCl2)3L2] (M = Pd; 13, Pt; 14) (L = 2,4,6-tris­{4-(diphenylphosphino)­phenyl}-1,3,5-triazine) and [(CuI)3L2] (15), in good yield.