Metal-templated diyne cyclodimerization and cyclotrimerization

Reaction of Pt(CH3)2(COD)] (COD = 1,5-cyclooctadiene) with Ph2PCCCCPPh2 led to a mixture of {Pt(CH3)2}2(mu-Ph2PC4PPh2)2] (1) and {Pt(CH3)2}3(mu-Ph2PC4PPh2)3] (2). Reaction of PtCl2(COD)] with Ph2PCCCCPPh2 led to a mixture of the thermally unstable compounds {PtCl2}2(mu-Ph2PC4PPh2)2] (3) and {PtCl2}3(mu-Ph2PC4PPh2)3] (4) which transform into {PtMe2}2{mu-C8(PPh2)4}] (5) and {PtMe2}3{mu3-C12(PPh2)6}] (6) containing 8-membered diene-diyne and 12-membered triene-triyne rings, respectively. Compound 2 can be converted to {PtMe2}3{C12(PPh2)6}] (7) by heating with CuCl at 80 degrees C, while 1 can be heated without significant cycloaddition.