The molecular structures of the complexes Pt(As(C6H5)3)2(F3CCCCF3), 1, and Pd(P(C6H11)3)2(F3CCCCF3), 2, have been determined from three-dimensional X-ray data collected by counter methods. Crystals of 1 are monoclinic, space group P21/c, with Z = 4 in a cell of dimensions a = 11.373(2), b = 15.154(2), c = 21.171(3) Å and β = 96.74(1)°; those of 2 are also monoclinic, space group Cc, with Z = 4, and cell dimensions a = 21.168(4), b = 10.603(2), c = 18.756(3) Å and β = 92.58(1)°. Intensity data collected on an automated four-circle diffractometer was used for full-matrix least-squares refinement on F, which converged for 1 at R = 0.038, 5687 observations, and for 2 at R = 0.049, 4386 observations. The coordination at the metal atom in the complexes is essentially planar, and the CC bond distances are not significantly different (1, 1.282(9); 2, 1.271(10) Å). The mean deviation from linearity of the alkyne molecule upon coordination is 40.8(5)° in 1 and 44.1(6)° in 2. These values are in agreement with the proposal that predominantly steric interactions, not electronic effects, cause variations in this angle.