Coordinate Covalent Research Articles

Surface species on manganese

Infrared spectra of the stable surface species formed at 25 °C by the interaction with a Mn surface of methanol, ethanol, n-propanol, n-butanol, isobutanol, 2-propanol, 2-butanol, t-butanol, diethyl ether, tetrahydrofuran, acetaldehyde, acetone, allyl alcohol, and methyl vinyl ether have been obtained. From the spectra it is concluded that: (i) alkoxides are quite stable surface species, (ii) a coordinate covalent bond of oxygen to the surface is not stable, (iii) the OH bond is readily broken, (iv) the degree of surface coverage by alkoxide structures is in the order primary > secondary > tertiary, (v) the CC bond does not strongly add to the surface, and (vi) the CH bond does not readily break at 25 °C to form dissociatively adsorbed hydrocarbons. It is suggested that attachment of a reacting complex to the Mn surface is more likely to be through an oxygen atom than a carbon atom.

Location of the Heme Moiety of Cytochrome c by Solvent Perturbation

Abstract The exposure of the heme moiety of cytochrome c to various solvents was investigated by the technique of solvent perturbation. The heme hexadecapeptide in a chymotryptic digest of the protein was used as a model compound for the fully exposed chromophore. While the Soret absorption of both ferri- and ferrocytochrome c was enhanced in 20% ethylene glycol, the extent of enhancement, Δe/e, was substantially less than that measured for the model compound or for the unfolded protein in 8 m urea. The percentage maximal perturbation of ferrocytochrome c was found to be independent of the radius of the perturbant over the range from 1.4 to 3.6 A. It was concluded that only a portion of the heme moiety of native cytochrome c is in contact with the solvent. Replacement of one of the two protein-heme coordinate-covalent bonds by cyanide increased the exposure of the heme to the solvent.

THE ELECTRIC MOMENT OF HYDROGEN PEROXIDE

The electric moment of hydrogen peroxide was found to be 2.13 × 10−18 in dioxan. Comparative measurements made on the electric moment of water gave 1.90 × 10−18 in dioxan. Measurements made with both water and hydrogen peroxide in ether gave lower values for their electric moments, and the reason for this is discussed. The structure of hydrogen peroxide is discussed, and the electric moment shown to be in agreement with all data as determined in this laboratory in indicating the presence of a co-ordinate co-valent bond.