phosphorus-transition metals have been studied. Folberth New phospho-silicide CoSi 3 P 3 has been synthesized and its and Pfister (5) prepared and studied CuSi 2 P 3 which is isocrystal structure determined by single crystal X-ray diffraction structural with ordered chalcopyrite. Vogel and Giessen (R β«Ψβ¬ 0.035, R W β«Ψβ¬ 0.042). CoSi 3 P 3 (Z β«Ψβ¬ 4) crystallizes with the (6) studied the iron-phosphorus-silicon phase diagram pseudo-orthorhombic symmetry and meriedric twinning in the and quoted the existence of the FeSi 4 P 4 compound. II'Nitspace group P2 1 . Lattice parameters are a β«Ψβ¬ 5.899(1) A Λ, b β«Ψβ¬ skaya and Kuz'ma studied the Ni-Si-P system ( 7) and 5.703(1) A Λ, c β«Ψβ¬ 12.736(1) A Λ, β€ β«Ψβ¬ 90Ψ. The crystal structure determined the crystal structure of Ni 1.68 Si 0.88 P 3 and can be described by zigzag chains of octahedra occupied by Co NiSi 3 P 4 (7, 8). No other phases containing transition metals atoms alternating with zigzag chains of tetrahedra occupied were reported when we decided to synthesize and characby P or Si atoms. Single crystals of this phase have been investiterize such ternary compounds. We have already reported gated at room temperature by polarized Raman spectroscopy the synthesis and crystal structure of new metal phosphoin the 100-600 cm Ψ1 range. The results confirm the monoclinic silicides M Si x P y with M Ο Fe, Co, Ni, Ru, Pd, Os, Ir, Pt symmetry of CoSi 3 P 3 . Magnetic susceptibility and electronic conductivity have been measured between 300 and 10 K. (9, 10). A detailed study of compounds M Si 4 P 4 (M Ο Fe, CoSi 3 P 3 is diamagnetic at room temperature and paramagnetic Ru, Os) (11) and M Si 3 P 3 (M Ο Rh, Ir) (12, 13) has been below 65 K. CoSi 3 P 3 is semiconducting at room temperature published. Recently, Jeitschko and colloborators began a with an energy gap of about 0.12 eV.