A phase transition caught in mid-course: independent and concomitant analyses of the monoclinic and triclinic structures of (BuN)[Co(orotate)(bipy)]·3HO.

The preparation and characterization of the BuN salts of two bis-orotate(2-) complexes of cobalt, namely bis(tetra-n-butylammonium) diaquabis(2,4-dioxo-1,2,3,4-tetrahydropyrimidin-1-ide-6-carboxylato-κN,O)cobalt(II) 1.8-hydrate, (CHN)[Co(CHNO)(HO)]·1.8HO, (1), and tetra-n-butylammonium (2,2'-bipyridine-κN,N')bis(2,4-dioxo-1,2,3,4-tetrahydropyrimidin-1-ide-6-carboxylato-κN,O)cobalt(III) trihydrate, (CHN)[Co(CHNO)(CHN)]·3HO, (2), are reported.

A discrete neutral transition-metal citrate cubane with an M₄O₄ core; coordinative versatility of the [M(II)₄(citrate)₄]⁸⁻ fragment.

The neutral cluster [Mn(II)8(citrate)4(H2O)18] is formed by the [M4(citrate)4](8-) fragment, with an Mn4O4 cubane core, which bonds four peripheral aquomanganese units--two [Mn(H2O)4](2+) and two [Mn(H2O)5](2+)--through a total of six metal-ligand bonds, giving a discrete neutral compound. The compound presents a unique coordination mode in which the citrate cubane acts as a chelate to each of the two peripheral [Mn(H2O)4](2+) (tetra-aquo) units. A detailed analysis of the central and peripheral geometries is given in terms of the tetrahedral distortions of key structural features.

A square two-dimensional polymer of cobalt citrate cubanes.

The structure of the title complex, poly[dicaesium(I) hexaaquacobalt(II) [octaaquatetra-μ-citrato-hexacobalt(II)] dodecahydrate], {Cs(2)[Co(H(2)O)(6)][Co(6)(C(6)H(4)O(7))(4)(H(2)O)(8)]·12H(2)O}(n), at 100 (1) K is formed by layers of a square two-dimensional polymer composed of Co(II) citrate cubanes bridged by magnetically active six-coordinate Co(II) cations. The polymer has plane symmetry p4mm in the c-axis projection. The cubanes reside on sites of crystallographic symmetry 4, while the bridging Co(II) centres lie on twofold axes.