Biomedical subjects

R E Gerkin

Publications and source records attributed to R E Gerkin.

At least 91 records · Page 5Linked to original sources

PubMed1993

Structure of dibenzofuran-d8, C12D8O, at 173 K.

Crystalline dibenzofuran-d8 has been found to exhibit disorder of the type described previously for dibenzofuran. The disordered molecules are related to the ordered molecules by a 180 degrees rotation about an axis passing through the molecular center of mass and perpendicular to the furan ring. In the present structure 11(2)% of the molecules were found to adopt this alternate orientation. The molecules are bisected by a mirror plane normal to the furan ring and containing the O atom. The average bond length in the benzenoid ring is 1.392 (10) A. The furan ring and the benzenoid ring are separately planar, but form a dihedral angle of 1.45 (9) degrees with each other.

Benzofurans↗

PubMed1993

Structure of 1,8-bis(hydroxymethyl)naphthalene.

1,8-Naphthalenedimethanol, C12H12O2, M(r) = 188.24, monoclinic, P2(1)/n, a = 8.549(4), b = 4.856(3), c = 22.604(4) A, beta = 94.24(3) degrees, V = 935.8(7) A 3, Z = 4, Dx = 1.34 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 0.84 cm-1, F(000) = 400, T = 295 K, R = 0.042 for 1455 unique reflections having I > 3 sigma I. In the title structure the exterior angles at ring atoms C(1), C(8) and C(9) deviate significantly from 120 degrees as a result of the steric interactions of the hydroxymethyl substituents. The ten C atoms comprising the naphthalene core have an average deviation of 0.012 (7) A from the best least-squares plane describing the core. The conformation of the title compound is compared to those of other 1,8-disubstituted naphthalenes. Each hydroxy group is involved in hydrogen bonding as both acceptor and donor, creating infinite chains that propagate in the [010] directions. The neutron-adjusted parameters for the two H...O(acceptor) distances are 1.78 (3) and 1.80 (3) A and for the two O--H...O(acceptor) angles are 165 (2) and 170 (2) degrees. The packing arrangement can be described as a modified herringbone structure with the shortest crystallographic axis coinciding with the b axis of the standard monoclinic setting.

Molecular Structure↗

PubMed1992

Structure of 2,3-naphthalenedicarboxylic acid.

C12H8O4, M(r) = 216.20, monoclinic, C2/c, a = 5.087 (2), b = 19.222 (3), c = 9.552 (2) A, beta = 93.81 (3) degrees, V = 932.0 (5) A3, Z = 4, Dx = 1.54 g cm-3, lambda = 0.71073 A, mu = 1.09 cm-1, F(000) = 488, T = 295 K, R = 0.037 for 687 unique reflections having I > 3 sigma (I). In the structure reported here, a twofold axis lies in the plane of the molecule and bisects the three central ring bonds. The average C--C bond distance in the naphthalene core is 1.401 (27) A and the average interior angle 120.0 (14) degrees. The average deviation of the C atoms comprising the naphthalene rings from the best least-squares plane describing the rings is 0.021 (8) A. The plane of the single unique carboxylic acid group makes a dihedral angle of 33.1 (1) degrees with the least-squares plane of the naphthalene core. The carboxylic acid group, in which the observed O--H distance is 1.00 (3) A, forms a cyclic-dimer hydrogen bond across a center of inversion with the H...O(acceptor) distance 1.68 (3) A, the O...O-(acceptor) distance 2.676 (2) A and the O--H...O-(acceptor) angle 174 (3) degrees. The C--O bond lengths indicate no disorder in the carboxylic acid dimers. The molecules are arranged in stacks with the naphthalene cores parallel to the (102) plane and with the hydrogen bonds of the acid groups linking adjacent stacks. This structure of 2,3-naphthalenedicarboxylic acid is essentially the same as that of o-phthalic acid, but with the b cell edge correspondingly larger to accommodate the additional aromatic ring.

Chemical Phenomena↗

PubMed1992

Structure of tetralithium 1,4,5,8-naphthalenetetracarboxylate dodecahydrate.

4Li+.C14H4O8(4-).12H2O, M(r) = 544.18, triclinic, P1, a = 9.608 (2), b = 10.034 (2), c = 7.033 (1) A, alpha = 94.29 (1), beta = 96.95 (1), gamma = 64.52 (1) degree, V = 607.4 (2) A3, Z = 1, D chi = 1.49 g cm-3, lambda (Mo K alpha) = 0.71073 A, mu = 1.29 cm-1, T = 295 K, F(000) = 284, R = 0.039 for 2781 unique reflections having I greater than sigma I. The two inequivalent carboxyl groups adopt a non-planar arrangement with respect to the naphthalene core, making dihedral angles of 52.7 (1) and 54.6 (1) degree with it. The Li+ ions are tetrahedrally coordinated by carboxyl and water O atoms. The Li-O distances are in the range 1.906 (3)-2.041 (3) A, averaging 1.97 (4) A; O-Li-O angles are 101.5 (1)-123.9 (1) degree, averaging 109 (6) degrees. Each of the 12 inequivalent water H atoms is involved in hydrogen bonding. Of these bonds, 11 are typical two-centered hydrogen bonds with an average H...O (acceptor) distance of 1.92 (11) A and an average O-H...O (acceptor) angle of 172 (5) degrees. One water H atom is involved in a three-centered hydrogen bond with an average H...O (acceptor) distance of 2.61 (4) A and an average O-H...O (acceptor) angle of 120 (3) degrees. Adjacent organic anions are separated by the Li+ ions and their coordination polyhedra, with the water molecules occupying positions above and below the naphthalene rings and participating in a three-dimensional hydrogen-bonded network.

Crystallization↗

PubMed1992

The structure of hexaaquaaluminium(III) bromate trihydrate, [Al(H2O)6](BrO3)3.3H2O.

Hexaaquaaluminium(III) bromate trihydrate, [Al(H2O)6](BrO3)3.3H2O, M(r) = 572.84, triclinic, P1, a = 9.536 (2), b = 11.095 (4), c = 9.291 (2) A, alpha = 106.58 (2), beta = 100.42 (2), gamma = 113.01 (2) degrees, V = 818.1 (4) A3, Z = 2, Dx = 2.33 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 74.58 cm-1, F(000) = 560, T = 296 K, R = 0.050 for 3777 unique reflections having I greater than sigma 1. The single type of Al ion is coordinated by six inequivalent water O atoms which form a slightly distorted octahedron. The average Al--O distance within the octahedron is 1.872 (11) A. Each of the three inequivalent bromate groups has three inequivalent O atoms. The average Br--O distances and O--Br--O angles for these ions are: 1.652 (25) A and 104.1 (17) degrees for Br(1)O3; 1.650 (9) A and 104.4 (18) degrees for Br(2)O3; 1.643 (9) A and 103.6 (14) degrees for Br(3)O3. The aluminium-oxygen complex conformed to rigid-body behavior but the bromate groups did not. Corrected for rigid-body motion, the average Al--O distance becomes 1.880 (10) A. Least-squares refinement of the positional parameters of the 18 inequivalent H atoms permitted a detailed analysis of the hydrogen bonding.

Aluminum↗

PubMed1992

1,2-Naphthalenedicarboxylic acid: structures of channel clathrates and an unsolvated crystalline phase.

(1) 1,2-Naphthalenedicarboxylic acid-diethyl ether, C12H8O4.nC4H10O, M(r) = 216.19, tetragonal, I4(1)/a, a = 22.086 (3), c = 9.463 (3) A, V = 4616 (2) A3, Z = 16, F(000) = 1792 (without ether), F(000) = 1873 (with 2.7 molecules of ether per unit cell), Dx = 1.24 g cm-3 (without ether), Dx = 1.31 g cm-3 (with 2.7 molecules of ether per unit cell), lambda(Mo K alpha) = 0.71073 A, T = 296 K, mu = 0.88 cm-1, R = 0.052 for 1130 unique reflections having I greater than 3 sigma I. (2) 1,2-Naphthalenedicarboxylic acid, C12H8O4, M(r) = 216.19, triclinic, P1, a = 9.027 (1), b = 9.234 (1), c = 7.256 (1) A, alpha = 106.08 (1), beta = 90.79 (1), gamma = 111.80 (1) degrees, V = 535.0 (1) A3, Z = 2, F(000) = 224, Dx = 1.34 g cm-3, lambda (Mo K alpha) = 0.71073 A, T = 296 K, mu = 0.95 cm-1, R = 0.043 for 1216 unique reflections having I greater than 3 sigma I. (3) 1,2-Naphthalenedicarboxylic acid-dimethoxyethane, C12H8O4.nC4H10O2, M(r) = 216.19, tetragonal, I4(1)/a, a = 22.067 (2), c = 9.465 (2) A, V = 4609 (1) A3, Z = 16, Dx = 1.25 g cm-3 (without dimethoxyethane), Dx = 1.39 g cm-3 (with 4.4 molecules of dimethoxyethane per unit cell), lambda(Mo K alpha) = 0.71073 A, T = 296 K.(ABSTRACT TRUNCATED AT 250 WORDS)

Clathrin↗

PubMed1992

Structure of sodium perbromate monohydrate.

NaBrO4.H2O, Mr = 184.90, monoclinic, C2/c, a = 15.7575 (19), b = 5.7373 (15), c = 11.3390 (19) A, beta = 111.193 (10)degrees, V = 955.8 (3) A3, Z = 8, Dx = 2.570 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 85.2 cm-1, F(000) = 704, T = 296 K, R = 0.039 for 1137 unique reflections having I greater than sigma I. In this structure, there are two inequivalent Na ions, each coordinated by six O atoms. In each of the two types of distorted octahedra, there are three inequivalent Na--O distances; the average Na(1)--O and Na(2)--O distances are 2.379 (10) and 2.405 (23) A, respectively. The perbromate ion in this structure displays very nearly regular tetrahedral geometry, although it is subject to no symmetry constraints; the average observed Br--O distance is 1.601 (4) A, while the average observed O--Br--O angle is 109.5 (9)degrees. These values agree well with previously reported values. The perbromate ion, but neither of the sodium coordination polyhedra, shows rigid-body behavior. The average rigid-body corrected Br--O distance in the perbromate ion is 1.624 (3) A. Refinement of the two inequivalent H atoms permitted detailed analysis of the hydrogen bonding, which is slightly different from that reported for the isomorphic sodium perchlorate monohydrate. Dynamic disordering of the H atoms as detailed by magnetic resonance methods for sodium perchlorate monohydrate is not clearly indicated in our X-ray study of sodium perbromate monohydrate.

Bromates↗

PubMed1992

Structure of the sodium salt of 1,4,5,8-naphthalenetetracarboxylic acid 4,5-anhydride hydrate.

Sodium hydrogen 1,3-dioxo-1H,3H-naphtho[1,8-cd]pyran-6,7-dicarboxylate hydrate, Na[C14H5O7].H2O, Mr = 326.2, triclinic, P1, a = 9.520 (2), b = 9.549 (3), c = 7.860 (1) A, alpha = 105.88 (2), beta = 110.29 (1), gamma = 100.89 (2) degrees, V = 611.9 (3) A3, Z = 2, Dx = 1.77 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 1.67 cm-1, F(000) = 332, T = 295 K, R = 0.042 for 1665 unique reflections having I greater than 3 sigma I. The organic portion of this structure demonstrates near-C2 symmetry with a pseudo-twofold axis coincident with the central C-C naphthalene ring bond. The atoms of the naphthopyran three-ring system deviate by an average of 0.037 (19) A from the best least-squares plane through the three rings. Each of the carboxyl group planes is substantially inclined to the naphthopyran ring plane, the average dihedral angle measuring 62 (1) degree. The Na ion is coordinated by O atoms in a highly distorted octahedral geometry with a mean Na--O distance of 2.49 (12) A. A short hydrogen bond is formed between a carboxylic acid group and a carboxylate anion; the H...O(acceptor) distance is 1.35 (5) A and the O...O(acceptor) distance is 2.475 (3) A. The acid H-atom position is located asymmetrically with respect to the O atoms. The water H atoms are involved in unequal three-centered hydrogen bonds. The molecules are stacked such that the naphthopyran ring portion of the structure is nearly parallel to the ab cell face and the stacks are connected by the hydrogen bonds.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemical Phenomena↗

PubMed1991

Structure of tetrasodium 1,4,5,8-naphthalenetetracarboxylate octahydrate.

Na4[C14H4O8].8H2O, Mr = 536.3, monoclinic, P2(1)/n, a = 6.142 (1), b = 8.144 (3), c = 20.527 (4) A, beta = 93.97 (1) degrees, V = 1024.4 (5) A3, Z = 2, Dx = 1.74 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 2.14 cm-1, F(000) = 552 T = 295 K, R = 0.039 for 1769 unique reflections having I greater than sigma I. In this structure, the title compound has an inversion center at the midpoint of the central naphthalene ring bond. The average C-C bond length in the naphthalene core is 1.41 (3) A; the average interior angle is 119.9 (1.0) degrees. The exterior angle at the central naphthalene carbon is 122.7 (3) degrees, significantly smaller than in 1.8-substituted naphthalenes. The two inequivalent carboxyl groups adopt a non-planar arrangement with respect to the naphthalene core, making an average dihedral angle of 53.8 (1) degree with it. The two inequivalent sodium ions have quite different environments. Na(1) is coordinated by six O atoms in a highly distorted octahedral arrangement with an average Na-O distance of 2.44 (10) A. Na(2) is coordinated by five O atoms in a highly distorted trigonal bipyramidal arrangement with an average Na-O distance of 2.36 (3) A. Each of the eight inequivalent water H atoms is involved in a single hydrogen bond. The average H...O (acceptor) distance is 2.00 (5) A, the average O...O (acceptor) distance is 2.85 (5) A and the average O-H...O (acceptor) angle is 165 (8) degrees for these hydrogen bonds.(ABSTRACT TRUNCATED AT 250 WORDS)

Crystallography↗

PubMed1991

Structure of 4-dibenzofurancarboxaldehyde, C13H8O2.

Mr = 196.21, monoclinic, P2(1)/n, a = 6.589 (1), b = 9.784 (2), c = 14.394 (2) A, beta = 95.69 (1) degrees, V = 923.4 (3) A3, Z = 4, Dx = 1.41 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 0.89 cm-1, F(000) = 408, T = 296 K, R = 0.048 for 964 unique reflections having I greater than 3 sigma I. The average C-C bond length within the benzenoid rings in 4-dibenzofurancarboxaldehyde is 1.388 (9) A; the average interior angle is 120.0 (2.6) degrees. While two of the three rings of 4-dibenzofurancarboxaldehyde are planar, the benzenoid ring to which the carbonyl group is attached is slightly non-planar. The dihedral angle between the two benzenoid rings measures 1.4(1) degrees. The structure is composed of pairs of 4-dibenzofurancarboxaldehyde molecules related by inversion centers. This structure is further characterized by approaches of both the carbonyl and the furan O atoms to ring H atoms with separations which are slightly less than the sum of the relevant van der Waals radii.

Benzofurans↗

PubMed1991

Structure of hexaaquacopper(II) bromate.

[Cu(H2O)6](BrO3)2, Mr = 427.44, cubic, Pa3, a = 10.3240 (6) A, V = 1100.38 (4) A3, Z = 4, Dx = 2.580 g cm-3, lambda (Mo K alpha) = 0.71073 A, mu = 92.32 cm-1, F(000) = 828, T = 296 K, R = 0.038 for 336 unique reflections having I greater than sigma I. The single type of copper ion (site symmetry 3) is coordinated by six water-molecule O atoms, each at an observed distance of 2.079 (4) A, in an array which is virtually regular octahedral, the nominal 90 degree angles measuring 89.95 (15) and 90.05 (15) degrees. Thus, this is not a typical CuII complex in which (consistent with a static Jahn-Teller effect) a distorted octahedral array displays '(2 + 2 + 2)' coordination; rather, it is the sixth strict example of a CuII static structure inconsistent with the Jahn-Teller theorem. The presence of a dynamic Jahn-Teller effect is supported by the data. The single type of bromate ion has an observed Br-O bond length 1.649 (3) A and O-Br-O bond angle 104.17 (15) degrees. The bromate ion was found to manifest rigid-body behavior but, consistent with a dynamic Jahn-Teller effect, the copper-oxygen complex did not. The Br-O bond length corrected for rigid-body motion is 1.663 A. Refinement of the positional parameters of the two inequivalent H atoms permitted a detailed analysis of hydrogen bonding, which occurs principally between the oxygen octahedra and the bromate groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Bromates↗

PubMed1991

Structure of 1,8-naphthalenedicarboxylic acid (naphthalic acid), C12H8O4: ring geometry and hydrogen-bonding effects.

C12H8O4, Mr = 216.19, orthorhombic, Pbca, a = 15.308 (2), b = 17.926 (2), c = 7.093 (2) A, V = 1946.4 (5) A3, Z = 8, Dx = 1.48 g cm-3, lambda (Mo K alpha) = 0.71073 A, mu = 1.05 cm-1, F(000) = 896, T = 296 K, R = 0.043 for 912 unique reflections having I greater than 3 sigma (I). In this structure, 1,8-naphthalenedicarboxylic acid departs significantly from planarity. While the average deviation of carbons from the best least-squares plane for the naphthalene core is 0.055 (4) A, the carboxyl carbons adopt positions +0.403 (4) and -0.350 (4) A from that plane. The carboxyl groups are twisted in the same direction with respect to that plane and make an average dihedral angle of 42.6 (3) degrees with it. The nearly equal lengths of the C--O distances within the carboxyl groups [mean value 1.267 (5) A] indicate almost complete disorder of the H atoms of these groups. Hydrogen bonding occurs in cyclic dimer fashion between two molecules related by a center of inversion. The carboxyl hydrogens appear to be subject to a symmetric double-minimum potential and to be disordered via tunneling; there is no evidence that the carboxyl oxygens are disordered. The mean carboxyl H--O acceptor distance is 1.90 (7) A.

Molecular Conformation↗

PubMed1991

Structure of hexaaquanickel(II) bromate.

[Ni(H2O)6](BrO3)2, Mr = 422.60, cubic, Pa3, a = 10.2987 (6) A, V = 1092.3 (2) A3, Z = 4, F(000) = 824, Dx = 2.57 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 90.79 cm-1, T = 296 K, R = 0.024 for 360 unique reflections having I greater than sigma I. The single type of nickel ion is coordinated by six water-molecule O atoms, each at an observed distance of 2.061 (2) A, in an almost regular octahedral array. The single type of bromate ion has an observed Br--O bond length of 1.655 (2) A and O--Br--O bond angle 104.25 (9) degrees. Both the nickel-oxygen complex and the bromate ion were found to manifest rigid-body behavior. The Ni--O distance corrected for rigid-body motion is 2.065 A, while the corrected Br--O bond length is 1.663 A. Location and refinement of the two inequivalent H atoms permitted a detailed analysis of the hydrogen bonding, which occurs principally between the oxygen octahedron and the bromate groups. This structure is isomorphic to the structures of hexaaquanickel(II) chlorate and hexaaquacobalt(II) bromate which have been reported recently from this laboratory.

Bromates↗

PubMed1991

Structure of tetraaquacopper(II) chlorate at 296 and 223 K.

[Cu(H2O)4](ClO3)2, Mr = 302.51, orthorhombic, Pbca, lambda (Mo K alpha) = 0.71069 A, Z = 4, F(000) = 604; T = 296 K, a = 12.924 (3), b = 9.502 (2), c = 7.233 (1) A, V = 888.3 (3) A3, D chi = 2.26 g cm-3, mu = 31.04 cm-1, R = 0.041 for 1174 unique reflections with I greater than sigma (I); T = 223 K, a = 12.853 (2), b = 9.492 (2), c = 7.216 (2) A, V = 880.4 (3) A3, D chi = 2.28 g cm-3, mu = 31.28 cm-1, R = 0.033 for 1279 unique reflections with I greater than sigma (I). The single type of copper ion is octahedrally coordinated by four water oxygens and two chlorate ion oxygens; the complex is characterized by three distinct pairs of Cu-O distances (which we have previously described as '2 + 2 + 2' coordination), one of which is substantially larger than the remaining two. The nominal 90 degrees O-Cu-O angles of the complex differ from that value by at most +/- 1.8 degrees. The observed structure of the complex is typical for copper(II) and is consistent with the Jahn-Teller effect. The single type of chlorate ion shows the expected trigonal pyramidal geometry, with average Cl-O bond lengths 1.485 (13) and 1.490 (11) A and average O-Cl-O bond angles 106.8 (13) and 106.8 (13) degrees for 296 and 223 K, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemical Phenomena↗

PubMed1991

Structure of phenoxathiin (phenothioxin), C12H8OS, at 223 K.

Mr = 200.25, orthorhombic, P2(1)2(1)2(1), a = 7.758(2), b = 20.506(3), c = 5.896(2) A, V = 938.0(4) A3, Z = 4, Dx = 1.42 g cm-3, lambda(Mo K alpha) = 0.71069 A, mu = 2.88 cm-1, F(000) = 416, T = 223 K, R = 0.044 for 1414 unique reflections having I greater than 3 sigma I. The phenoxathiin molecule is constituted of two very nearly regular planar hexagonal carbocyclic (benzenoid) rings joined to a non-planar heterocyclic ring. The heterocyclic ring geometry is described in terms of two intersecting planes between which the dihedral angle, the molecular fold angle, is 142.3 degrees. The angle at S (C-S-C) is 97.7(1) degrees, while the angle at O (C-O-C) is 117.4(2) degrees. The overall mean C-C distance in the carbocyclic rings is 1.387(7) A. The absence in this structure of the type of disorder previously found in the dibenzofuran structure is readily understandable since eight sets of close approaches involving each molecule were found in the present structure. These close approaches involve S and O atoms as well as H atoms.

Heterocyclic Compounds↗

PubMed1991

Structure of tetraaquacobalt(II) bromide dihydrate (cobalt bromide hexahydrate).

Tetraaquacobalt(II) bromide dihydrate, [Co(H2O)4]Br2 x 2H2O, Mr = 326.83, monoclinic, C2/m, a = 11.0158(12), b = 7.1694(10), c = 6.9111(10) A, beta = 124.761(7)degrees, V = 448.4(1) A3, Z = 2, F(000) = 314, Dx = 2.420 g cm-3, lambda(Mo K alpha) = 0.71069 A, T = 296 K, mu = 107.13 cm-1, R = 0.022 for 532 unique reflections having I greater than 0. The single type of Co ion is octahedrally coordinated by four equivalent water-molecule O atoms at the observed distance 2.081(2) A and two equivalent Br ions at the observed distance 2.6048(5) A in an array which, with respect to its angles, departs only slightly from regular octahedral geometry. The cobalt-oxygen-bromine complex was found to manifest rigid-body behavior. The cobalt-oxygen distance corrected for rigid-body motion was found to be 2.088 A; the corrected cobalt-bromine distance, 2.6081 A. Associated with each complex are two water molecules of hydration. Assignment and refinement of the coordinates of the four non-equivalent H atoms permitted detailed analysis of the hydrogen bonding, which involves each of the four non-equivalent H atoms significantly. The structure as determined in this study differs markedly from that presented in the sole published single-crystal study [Stroganov, Andreev, Kozina & Solov'ev (1961). Vestn. Leningr. Univ. Ser. Mat. Fiz. Khim. 16, 114-119]. In particular, the space-group assignment differs and the pattern of bromine-oxygen distances is quite different. Contrary to Stroganov et al., this structure is isomorphic with that of cobalt chloride hexahydrate.

Bromides↗

PubMed1990

Structure of hexaaquacobalt(II) bromate.

[Co(H2O)6](BrO3)2, Mr = 422.83, cubic, Pa-3, a = 10.3505 (7) A, V = 1108.88 (8) A3, Z = 4, Dx = 2.53 g cm-3, lambda(Mo K-alpha) = 0.71069 A, mu = 87.31 cm-1, F(000) = 820, T = 296 K, R = 0.027 for 365 unique reflections having I greater than sigma I. The single type of Co ion is coordinated by six water-molecule O atoms, each at an observed distance 2.095 (2) A, in an array which is regular octahedral within the estimated standard deviations of the relevant angles. The single type of bromate ion has a Br-O bond length 1.653 (2) A and O-Br-O bond angle 104.07 (9) degrees. The cobalt-oxygen complex manifested rigid-body behavior, but the bromate ion did not. The cobalt-oxygen distance corrected for rigid-body motion is 2.099 A. Location and refinement of the two inequivalent H atoms permitted detailed analysis of the hydrogen bonding, which occurs principally between the oxygen octahedra and the bromate groups. This structure is isomorphic to that of hexa-aquanickel(II) chlorate recently reported from this laboratory.

Bromates↗

PubMed1990

Structure of nickel(II) perbromate hexahydrate at 296 K.

Ni(BrO4)2.6H2O, Mr = 454.61, trigonal, P3, a = 7.874 (1), c = 5.423 (2) A, V = 291.2 (1) A3, Z = 1, D chi = 2.59 g cm-3, lambda(Mo K alpha) = 0.71069 A, mu = 85.36 cm-1, F(000) = 222, T = 296 K, R = 0.029 for 457 unique reflections having I greater than 0. The room-temperature structure is very similar to that reported previously for a sample at 169 K. The water O atoms form a very slightly distorted octahedron about nickel while the perbromate-ion geometry is virtually regular tetrahedral. Both the coordination polyhedron and the perbromate ion were tested and found to behave as rigid bodies. Corrected for rigid-body motion, the Ni--O(2) distance is 2.064 (2) A and the mean Br--O distance in the perbromate ion is 1.629 (3) A. A detailed account of the hydrogen bonding is presented. The structure previously determined at 169 K is most probably not the stable structure at that temperature.

Bromates↗