A Quest for Platinum(0) Adducts of the Macrocyclic Dibridgehead Diphosphine P((CH2)14)3P

The reaction of trans-Pt(Cl)2(P((CH2)14)3P) and C8K in C6D6 or diethyl ether cleanly gives a species provisionally formulated as trans-Pt(P((CH2)14)3P) (trans-5) based upon NMR data (31P{1H} chemical shift and JPPt values similar to other trans-Pt(PR3)2 species; seven 13C NMR signals, three exhibiting JCP). Consistent with a platinum(0) formulation, addition of CH3I gives the known complex trans-Pt(I)(Me)(P((CH2)14)3P) (trans-10, 83% isolated), and H2 gives the dihydride complex trans-Pt(H)2(P((CH2)14)3P) (trans-11), as evidenced by 31P{1H} and 1H NMR. Additions of ethylene and diphenylacetylene give the corresponding 1:1 π adducts, be¬lieved to have trigonal geometries based upon literature precedent. Alternative formulations or trans-5 are discussed; the 1H NMR spectrum of one sample showed a weak upfield triplet integrat¬ing to < 0.25 H, (–2.43 ppm, JHP = 18.6 Hz), suggesting a Pt-H unit.