ALBERT

Description: The asymmetric unit of the title compound, [MnCl2(C16H20N2O)4]·2C16H20N2O, is composed of two coordinating N-(adamantan-1-yl)pyridine-4-carboxamide molecules, one Cl− anion, an MnII ion, lying on an inversion centre, and one free N-(adamantan-1-yl)pyridine-4-carboxamide molecule. The distorted octahedral Mn environment comprises two terminal Cl atoms and four monodentate N atoms from four organic ligands. All the carbamoyl N atoms are involved in intermolecular N—H...O hydrogen-bonding interactions which link the molecules into a chain along the a axis.

Description: During the formation of the title salt, C7H10N+·C3H3O4−, an H atom of a carboxyl group was transferred to the amino group. All non-H atoms of the cation are essentially coplanar [r.m.s. deviation = 0.007 (4) Å]. The mean planes of the carboxylate and carboxyl groups of the anion form a dihedral of 69.67 (1)°. In the crystal, N—H...O and O—H...O hydrogen bonds connect the anions and cations, forming a two-dimensional network parallel to the bc plane.

Description: The asymmetric unit of the title compound, C6H5N2+·H2PO4−·C6H4N2·H3PO4, contains one 4-cyanopyridinium cation, one H2PO4− anion, one independent isonicotinonitrile molecule and one independent H3PO4 molecule. The dihedral angle between the mean planes of the separate protonated and unprotonated pyridine rings is 9.93 (8)°. In the crystal, N—H...O and O—H...N hydrogen bonds and weak C—H...O and C—H...N intermolecular interactions connect the organic molecules into a two-dimensional network parallel to the ac plane. O—H...O hydrogen-bonding interactions involving the H2PO4− anions and H3PO4 molecules provide additional support from the inorganic groups Weak π–π stacking interactions between the pyridine rings of neighbouring organic molecules [centroid–centroid distances = 3.711 (4) and 3.784 (2) Å] further link the layers into a three-dimensional network.

Description: In the centrosymmetric dimeric title compound, [Cu2Cl4(C16H20N2O)4]·0.5H2O, the CuII atom is in a distorted trigonal–bipyramidal environment defined by two bridging Cl atoms, one terminal Cl atom and two N atoms from two monodentate 4-(adamantan-1-ylcarbamoyl)pyridine ligands. The amine N atoms are involved in intramolecular N—H...O and intermolecular N—H...Cl hydrogen bonds. The latter hydrogen bonds link the complex molecules into a ribbon along [010]. The uncoordinated water molecule is 0.25-occupied.

Description: The asymmetric unit of the title complex, [Fe(C5H5)(C11H17N)]ClO4, contains two independent allyl(ferrocenylmethyl)dimethylammonium cations and two ClO4− anions. The anions are disordered each over two sets of sites, with an occupancy ratio of 0.617 (6):0.383 (6). The distances from the Fe atoms to the centroids of the unsubstituted and substituted cyclopentadienyl (Cp) rings are 1.645 (1)/1.657 (1) and 1.644 (1)/1.647 (1) Å. The dihedral angles between the two Cp rings are 2.49 (3) and 1.45 (4)° in the two ferrocenyl groups of the cations.

Description: The asymmetric unit of the title complex, {(C5H12NO)[BiCl4]}n, contains two bridging and two cis non-bridging chloride ligands coordinated to a central BiIII atom, and one 4-methylmorpholin-4-ium cation. The BiIII atoms are linked by the bridging chloride ligands into linear chains parallel to the c axis. The chloride ions create a pseudo-octahedral geometry about each BiIII atom. Bifurcated N—H...Cl hydrogen bonds link the cations to the anionic chains.

Description: The asymmetric unit of the title complex, [Fe(C5H5)(C9H15N)]ClO4, contains one discrete (ferrocenylmethyl)trimethylammonium cation and one perchlorate anion. The anion is disordered over two sets of sites, with refined occupancies of 0.776 (8) and 0.224 (8). The distances from the Fe atom to the centroids of the unsubstituted and substituted cyclopentadienyl (Cp) rings are 1.650 (1) and 1.640 (1) Å, respectively. The Cp rings form a dihedral angle of 2.66 (3)°.

Description: Lower Cretaceous pedogenic carbonates exposed in SE China have been dated by U–Pb isotope measurements on single zircons taken from intercalated volcanic rocks, and the ages integrated with existing stratigraphy. 13 C values of calcretes range from –7.0 to –3.0 and can be grouped into five episodes of increasing–decreasing values. The carbon isotope proxy derived from these palaeosol carbonates suggests p CO 2 mostly in the range 1000–2000 parts per million by volume (ppmV) at S ( z ) (CO 2 contributed by soil respiration) = 2500 ppmV and 25°C during the Hauterivian–Albian interval ( c . 30 Ma duration). Such atmospheric CO 2 levels are 4–8 times pre-industrial values, almost double those estimated by geochemical modelling and much higher than those established from stomatal indices in fossil plants. Rapid rises in p CO 2 are identified for early Hauterivian, middle Barremian, late Aptian, early Albian and middle Albian time, and rapid falls for intervening periods. These episodic cyclic changes in p CO 2 are not attributed to local tectonism and volcanism but rather to global changes. The relationship between reconstructed p CO 2 and the development of large igneous provinces (LIPs) remains unclear, although large-scale extrusion of basalt may well be responsible for relatively high atmospheric levels of this greenhouse gas. Suggested levels of relatively low p CO 2 correspond in timing to intervals of regional to global enrichment of marine carbon in sediments and negative carbon isotope ( 13 C) excursions characteristic of the oceanic anoxic events OAE1a (Selli Event), Kilian and Paquier events (constituting part of the OAE 1b cluster) and OAE1d. Short-term episodes of high p CO 2 coincide with negligible carbon isotope excursions associated with the Faraoni Event and the Jacob Event. Given that episodes of regional organic carbon burial would draw down CO 2 and negative 13 C excursions indicate the addition of isotopically light carbon to the ocean–atmosphere system, controls on the carbon cycle in controlling p CO 2 during Early Cretaceous time were clearly complex and made more so by atmospheric composition also being affected by changes in silicate weathering intensity.