New Tetraphosphane Ligands {(X2P)2NC6H4N(PX2)2} (X = Cl, F, OMe, OC6H4OMe-o): Synthesis, Derivatization, Group 10 and 11 Metal Complexes and Catalytic Investigations. DFT Calculations on Intermolecular P···P Interactions in Halo-Phosphines

Abstract

The reaction of p-phenylenediamine with excess PCl3 in the presence of pyridine affords p-C6H4[N(PCl2)2]2 (1) in good yield. Fluorination of 1 with SbF3 produces p-C6H4[N(PF2)2]2 (2). The aminotetra(phosphonites) p-C6H4[N{P(OC6H4OMe-o)2}2]2 (3) and p-C6H4[N{P(OMe)2}2]2 (4) have been prepared by reacting 1 with appropriate amount of 2-(methoxy)phenol or methanol, respectively, in the presence of triethylamine. The reactions of 3 and 4 with H2O2, elemental sulfur, or selenium afforded the tetrachalcogenides, p-C6H4[N{P(O)(OC6H4OMe-o)2}2]2 (5), p-C6H4[N{P(S)(OMe)2}2]2 (6), and p-C6H4[N{P(Se)(OMe)2}2]2 (7) in good yield. Reactions of 3 with [M(COD)Cl2] (M = Pd or Pt) (COD = cycloocta-1,5-diene) resulted in the formation of the chelate complexes, [M2Cl4-p-C6H4{N{P(OC6H4OMe-o)2}2}2] (8, M = Pd and 9, M = Pt). The reactions of 3 with 4 equiv of CuX (X = Br and I) produce the tetranuclear complexes, [Cu4(μ2-X)4(NCCH3)4-p-C6H4{N(P(OC6H4OMe-o)2)2}2] (10, X = Br; 11, X = I). The molecular structures of 1−3, 6, 7, and 9−11 are confirmed by single-crystal X-ray diffraction studies. The weak intermolecular P···P interactions observed in 1 leads to the formation of a 2D sheetlike structure, which is also examined by DFT calculations. The catalytic activity of the Pd(II) 8 has been investigated in Suzuki−Miyaura cross-coupling reactions.