Multinuclear Palladium Olefin Polymerization Catalysts Based on Self-Assembled Zinc Phosphonate Cages

Abstract

The phosphine–phosphonate–sulfonate proligand HP+(4-tBu-Ph)(2-PO3H2-5-Me-Ph)(2-SO3–-5-Me-Ph) (H3[OP-P-SO], 1-H3) was investigated as a building block for the self-assembly of multinuclear Pd compounds based on zinc phosphonate scaffolds. 1-H3 reacts with Zn(OAc)2·2H2O to afford {Zn[1-H]}4, which adopts a Zn4P4O8 ring structure in which the Zn centers are linked by μ2-κ1,κ1-bridging (aryl)PO3H– ligands. {Zn[1-H]}4 reacts with (TMEDA)PdMe2 and pyridine to generate {[(κ2-OP-P-SO)PdMe(py)][Zn(TMEDA)]}2 (2), in which two [(κ2-OP-P-SO)PdMe(py)]2– units are linked through a Zn2P2O4 ring. The sequential reaction of CH3OH-free {Zn[1-H]}4 with (COD)PdMe2 and 4-tBu-py generates {[κ2-(Zn-OP-P-SO)]PdMe(4-tBu-py)}4 (4-(4-tBu-py)), in which four [(κ2-OP-P-SO)PdMe(4-tBu-py)]2– units are arranged on the periphery of a double-four-ring (D4R) Zn4P4O12 cage. Analogous 4-L species were generated by the reaction of {Zn[1-H]}4, (COD)PdMe2, and other pyridine ligands. 4-py reacts with CH3OH to form a trimeric cluster 3-py, which...