During this period final calculations were performed and the manuscript was prepared.Registry No. [Te(etu)4]Cl2-2H20, 63848-47-5.

Summavy A single-crystal X-ray structure analysis of Prussian Blue, Fe, [Fe(CN),],, 14H,O, reveals that the space group symmetry of the approximate structure is O:-Fm3m with occupancy factors of 0.75 for Fen, C, and N ; the more detailed investigation demonstrates deviations from the cubic face-centred symmetry.PRUSSIAN BLUE is considered to be the oldest synthetic co-ordination compound. Until now no single-crystals could be grown, mainly due to the low solubility of this compound.lS2 The complete crystal structure has therefore not yet been solved, but a structural model with space group symmetry Fm3m was deduced from powder data., Prussian Blue has been prepared by diffusion of aerial oxygen and water vapour into a solution of FeCl, and K,Fe(CN), in 1 0 ~ HCl., The cubelike crystals of composition Fe,[Fe(CN),],, 14H,O were contaminated by 1-274 K+ and C1-.

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

Since the early 18 th century1 the iron cyanide complex called Prussian Blue has repeatedly attracted the interest of chemists. The most striking feature of this classical coordination compound, the intense blue colour, is observed in neither of the components, Fe3+ and jFe(CiV)64_. This feature has instigated many investigations and speculations concerning its structure and bonding. Purthermore, Prussian Blue was very often used as a test substance when new

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