The crystal structure of the title compound has been determined from diffractometer data. Crystals are cubic, a = 10.91 1 (4) A, Z = 4, space group Fm3m. The structure has been refined by least-squares techniques to R 0.057 for 172 observed independent reflections. Interatomic distances are : Pd-C 2-07(2), Cd-N 2.27(3), and C-N 1 . l l ( 4 ) A.THE crystal structures of a variety of cubic polynuclear transition-metal cyanides have been described in terms of a general structural mode1.l Corresponding crystallographic studies have been carried out so far with compounds of the composition M11s[M111(CN)6]2,xHa0. A particular property of these structures is given by a stoic heionietrically determined fraction of vacant lattice sites which are assumed to occur completely at random.2 I n the case of Cd[Pd(CN),] the general model predicts a three-dimensional framework without vacancies. The present X-ray study was undertaken to test the validity of our general structural description. The determination of this structure was further initiated by the lack of structural data for cyano-complexes of palladium(1v).half the edge of the complete face-centred cell. Because of the existence of the pseudo-mirror-plane intersecting the sequence M-C-N-M', the even-index reflections did not allow a distinction to be made between Cd and Pd, or between C and N. The small number and the low intensity of the oddindex reflections provided insufficient information for us conclusively to distinguish between the possible ordered arrangements Pd-C-N-Cd and Pd-N-C-Cd, or the disordered structure (Cd,Pd)-( c , N) -( C,N)- ( Cd , Pd) . Further experimental data, in addition to X-ray intensities, had therefore to be used. Chemical intuition predicted the linkage Pd-C-N-Cd, by consideration of the structures of other cadmium-cyanometallates. This arrangement, i .e. [Pdc,] and [CdN,] octahedra, is in complete agreement with X ray photoelectron spectra. The ionization potentials of the 3d312, 3d5l2, aiid 4d orbitals of Cd in Cd[Fd(CK),] are 4 9.8, EXPEKIMEXTAL Crystals of Cd[Pd(CS),j wcre prepared as described in ref.2. The crystal used was a cube, cu. 0.10 x 0-10 x 0.09 mni. Crystal hta.-Cd[Pd(CN),], &%f = 374.9 cubic, a = 10.911(4) A, U = 1209 A3, D , = 1.92(1) (by flotation), 2 = 4, D, == 1-92, F(000) = 688. Filtered Mo-A' , radi-[3/774
