L. O. Brockway

The Crystal Structure of Chalcopyrite CuFeS2

An investigation of the crystal structure of chalcopyrite was made in this Laboratory in 1917 by B u r d i c k and El l i s 1 ) , who measured the angles and intensities of reflection in successive orders of the palladium /^-doublet from seven different faces ground on a sphenoidal crystal. Their observations were completely explained by an atomic arrangement based on a pseudo-cubic unit of structure, with a0 = 5.24 Â and c 0 = 5.15 Â (calculated from their reported angles of reflection by using the wavelength 0.5857 A for Pd Ka). No odd-order reflections were observed except from planes with all indices odd, showing that the structure must approximate a face-centered arrangement. B u r d i c k and E l l i s suggested a structure closely similar to that of sphalerite, the atomic positions being

The Molecular Structure of Nickel Carbonyl

Electron diffraction by the vapor of Ni(CO)4 leads to a molecular model in which the four carbonyl groups have a tetrahedral arrangement about the nickel atom with the distances Ni – C = 1.82±0.03A and C – O = 1.15A. These distances are compatible with resonance between two electronic structures in which the C – O bond resonates between triple and double electron pair bonds and the Ni – C bond between single and double electron pair bonds. Nickel carbonyl is the first quadricovalent compound of neutral nickel whose structure has been determined, and its tetrahedral configuration is contrasted with the square arrangement of bonds in the quadricovalent compounds of divalent nickel ion.

The Molecular Structures of Sulfur Dioxide, Carbon Disulfide, and Carbonyl Sulfide

The structures of the molecules SO2, CS2, and COS have been investigated by the electron diffraction method with the following results; SO2, S – O = 1.46±0.02A; CS2, C – S = 1.54±0.03A; COS, C – O = 1.16±0.02A, C – S = 1.56±0.03A. The types of bond arrangement compatible with these interatomic distances are discussed. In SO2 the molecule resonates between the structures having single‐double and double‐single bonds between the sulfur and the two oxygen atoms, with a bond angle of 122°±5°. CS2 is a linear molecule with the structure having the two double bonds predominating over those having a single and a triple bond. In COS the double‐double bond arrangement and the structure having the triple carbon‐oxygen bond predominate.