The synthesis and characterization, including detailed 'H, 2H, 31P, and 13C NMR analysis of [ (l,l-dideuteri0-2,2-dimethyl-4-penten-l-yl-K3C~~~*~) (dmpe)PtnlBF4, 1-adz, and its 3,3-dideuterio isotopomer, 1 -7 4 (dmpe = 1,2-bis(dimethylphosphino)ethane), are described. Thermolysis of each 1-a-dz and 1-y-dz was carried out a t 125 "C in several solvents to yield a 1/1 mixture of 1-a-dz and 1-ydz. The rate of rearrangement is cleanly first order. Thermolysis of 1-a-d2 between 81 and 125 "C in methylene chloride led to determinations of activation parameters, E, = 31.8(0.6) kcal/moland AS* = -0.5(1.6) eu (100 "C). AnX-ray crystalstructuredetermination was carried out on the compound. It crystallizes in the monoclinic space group P21/n (No. 14), with a = 19.337(11) A, b = 6.948(4) A, c = 17.260(9) A, B = 122.34(6)", V = 1959.3 A3, and 2 = 4. The structure was solved with heavy atom techniques and refined to a final R factor of 4.18 % . In the solid state, the coordinated vinyl group is slipped slightly out the plane of the molecule and is canted a t a dihedral angle of 52" from the molecular plane. The chelate ring shows only very slight distortions from a presumed strain-free shape. 2D NOESY spectra suggest that the in-plane conformation of the pentenyl chelate is at least partly populated in solution. (dmpe)Pt(CH2-c-C4H,)Cl, 11, was prepared. Thermolysis of 11 a t 110 "C yielded intractable metal-containing materials along with methylenecyclobutane and methylcyclobutane together in ca. 60 7% yield as the only identifiable organic products. Treatment of 11 with silver ion a t low temperatures in acetone or methylene chloride yielded two products in a 1:7 (NMR) ratio, methylenecyclobutane and a material stable only below 0 "C that is assigned the structure [ (4-penten-l-y1-~3C~~~~~)(dmpe)PtII]BF4 on the basis of its NMR spectrum.
