Biomedical subjects

R E Gerkin

Publications and source records attributed to R E Gerkin.

93 records · Page 6Linked to original sources

PubMed1990

The structure of hexaaquanickel(II) chlorate.

Hexaaquanickel(II) chlorate, [Ni(H2O)6]-(ClO3)2, Mr = 333.69, cubic, Pa3-, a = 10.3159 (5) A, V = 1097.80 (5) A3, Z = 4, F(000) = 680, Dx = 2.02 g cm-3, lambda(Mo K alpha-) = 0.71069 A, T = 296 K, mu = 23.13 cm-1, R = 0.026 for 388 unique reflections having I greater than sigma I. The single type of Ni ion is coordinated by six water-molecule O atoms, each at an observed distance 2.054 (1) A, in an almost regular octahedral array. The single type of chlorate ion has a Cl--O bond length 1.487 (1) A and O--Cl--O bond angle 106.45 (6) degrees. The Ni--O complex, but not the chlorate ion, manifested rigid-body behavior. The Ni--O distance corrected for rigid-body motion is 2.060 A. Location and refinement of the two inequivalent H atoms permitted a detailed analysis of hydrogen bonding, which occurs principally between the oxygen octahedra and the chlorate groups.

Chlorates↗

PubMed1989

Structure of copper(II) perchlorate hexahydrate.

Cu(ClO4)2.6H2O, Mr = 370.54, monoclinic, P2(1)/c, a = 5.137 (1), b = 22.991 (3), c = 13.849 (2) A, beta = 90.66 (1) degree, V = 1635.4 (4) A3, Z = 6, Dx = 2.26 g cm-3, lambda(Mo K alpha) = 0.71069 A, mu = 26.44 cm-1, T = 296 K, F(000) = 1122, 2911 unique reflections having I greater than sigma 1, R = 0.030. Each of the two inequivalent copper ions is coordinated by six water-molecule O atoms in a significantly distorted octahedral arrangement. Each of the three inequivalent but geometrically quite similar perchlorate groups is slightly distorted from regular tetrahedral geometry. The overall observed mean Cl-O distance is 1.429 (5) A while the overall observed mean perchlorate O-O distance is 2.333 (8) A. Both the Cu-O complexes and the perchlorate ions were tested and found to behave as rigid bodies. The perchlorate-ion parameters corrected for rigid-body motion are: overall mean Cl-O distance, 1.453 (6) A; overall mean perchlorate O-O distance, 2.372 (8) A. Location and refinement of the 18 H atoms gave a detailed account of hydrogen bonding, which occurs between oxygen octahedra, between oxygen octahedra and perchlorate groups, and, more weakly, within oxygen octahedra.

Chemical Phenomena↗

PubMed1988

Structure of barium perchlorate trihydrate.

Ba(ClO4)2.3H2O, Mr = 390.28, hexagonal, P63/m, a = 7.277 (2), c = 9.656 (1) A, V = 442.9 (1) A3, Z = 2, F(000) = 368, D chi = 2.93 g cm3, lambda(Mo K alpha) = 0.71069 A, T = 295 K, mu = 52.60 cm1, 456 unique reflections, R = 0.023. The barium atoms in this structure are coordinated by six water oxygens, O(3), at 2.919 (1) A and by six perchlorate oxygens, O(2), at 3.026 (2) A in a slightly distorted icosahedral arrangement, the average Ba-O separation thus being approximately 2.97 A. The perchlorate ion just fails to have regular tetrahedral geometry within the experimental error, and has an average Cl-O bond length of 1.433 (6) A. Consistent with hydrogen bonding delineated on the basis of least-squares-refined hydrogen-atom positions, each axial [O(1)] perchlorate oxygen is hydrogen bonded to three water molecules and each trigonal [O(2)] perchlorate oxygen is hydrogen bonded to two water molecules; thus each perchlorate ion is hydrogen bonded to nine water molecules. Conversely, each water molecule [O(3)] oxygen is hydrogen bonded to six perchlorate ions to two through axial [O(1)] oxygens and to four through trigonal [O(2)] oxygens.

Barium↗