Palladium(II) and platinum(II) complexes with 1,4,8,11-tetramethyl-1,4,8,11-tetraphosphacyclotetradecane were prepared by a template reaction in which [M(MeHPCH(2)CH(2)PHMe)(2)]Cl-2 (M = Pd, Pt) reacts with 1,3-dibromopropane in the presence of K2HPO4 as a base. the bromide salts of the Pd2+(61) and Pt2+(6b) complexes were isolated as crystals in a low yield. Their molecular structures were determined by X-ray crystallography. Both compounds have a square-planar geometry in which the configurations of the four asymmetric phosphorus atoms are of the trans III (RRSS) type. The M-P bond distances for 6a and 6b are 2.268(1) and 2.277(1) Angstrom, respectively, which are slightly smaller than those of the complexes with noncyclic phosphines. Crystallographic data for 6a : monoclinic, space group C2/m, a = 8.4856(7) Angstrom, b = 17.273(1) Angstrom, c = 9.5712(7) Angstrom, beta = 101.117-(7)degrees, V = 1376.5(2) Angstrom(3), Z = 2, and R = 0.042. Crystallographic data for 6b : triclinic, space group <(P)over bar 1>, a = 9.538(3) Angstrom, b = 9.781(2) Angstrom, c = 8.719(1) Angstrom, alpha = 115.34(2)degrees, beta = 92.92(2)degrees, gamma = 61.33(2)degrees, v = 632.6(3) Angstrom(3), Z = 1, and R = 0.041.