A cyclodiphosphazane based pincer ligand, [2,6-{μ-(tBuN)2P(tBuHN)PO}2C6H3I]: NiII, PdII, PtII and CuI complexes and catalytic studies

Abstract

Synthesis and late-transition metal complexes of pincer capable cyclodiphosphazane, 2,6-{μ-(^tBuN)₂P(^tBuHN)PO}₂C₆H₃I (1) are described. The condensation of 2-iodoresorcinol with cis-{ClP(μ-N^tBu)₂PN(H)^tBu} produced a difunctional derivative 1 in good yield. The treatment of Ni(COD)₂, Pd₂(dba)₃·CHCl₃ or Pt(PPh₃)₄ with 1 afforded pincer complexes [2,6-{μ-(^tBuN)₂P(^tBuHN)PO}₂C₆H₃MI] (2 M = Ni; 3 M = Pd and 4 M = Pt). The reaction of complex 3 with copper halides resulted in the formation of heterobimetallic complexes bridged by rhombic {Cu(μ-X)}₂ units, [{{Cu(μ-X)}₂}{μ-(^tBuN)₂P(^tBuHN)PO}₂C₆H₃PdI] (5 X = I and 6 X = Br). The crystal structures of 1–3, 5 and 6 were established by single X-ray diffraction studies. The palladium complex 3 was tested for catalytic P-arylation of diphenylphosphine oxide (Ph₂P(O)H) under microwave irradiation. Moderate to good catalytic activity was observed with aryl bromides.