Kinetics and mechanism of acid and base hydrolysis ofcis-chloro-(benzotriazole)bis(ethylenediamine)cobalt(III) andcis-chloro-(N-methylbenzotriazole)bis(ethylenediamine)cobalt(III) cations

Summary The kinetics of acid hydrolysis ofcis-[CoCl(btzH)(en)₂]²⁺ andcis-[CoCl(btzMe)(en)₂]²⁺ complexes (where btzH = benzotriazole, btzMe =N-methylbenzotriazole and en = ethylenediamine) have been investigated in HClO₄ at ionic strength 1 = 0.25 mol dm^–3 in the 30–40° range. In the 1.0 x 10^–1 to 1.0 X 10^–3 mol dm^–3 acid strength range, the rate of aquation of the [CoCl(btzH)(en)₂]²⁺ cation follows the relationship:-d ln[complex]/dt = k₁ + k₂K_NH[^H+]^–1, where k₁ and k₂ are aquation rate constants of the acid independent and acid dependent steps respectively, and K_NH is the acid dissociation constant of the coordinated benzotriazole.cis-[CoCl(btzMe)-(en)₂]²⁺ undergoes acid independent hydrolysis presumably due to the absence of a labile N-H proton. The base hydrolysis could be followed for thecis-[CoCl(btzMe)(en)₂]²⁺ complex only by measuring hydrolysis rates at 0°.     

Two polymorphs of tris(ethylenediamine)cobalt(III) tetrathioantimonate(V)

Details of the structures of two polymorphs of tris(ethylenediamine)cobalt(III) tetrathioantimonate(V), [Co(C₂H₈N₂)₃][SbS₄], are reported. The first polymorph crystallizes in the orthorhombic space group Pna2₁, whereas the second polymorph belongs to the tetragonal space group P4₂bc. Both structures contain octahedral [Co(en)₃]³⁺ cations (en is ethylenediamine) and tetrahedral [SbS₄]³⁻ anions, which are interconnected via various N—H...S hydrogen bonds to form two different types of three‐dimensional network.     

The first oxygen-bonded sulfenate ion: crystal and molecular structures of bis(ethylenediamine)(2-pyridinesulfenato-O)cobalt(III) and bis(ethylenediamine)(2-pyridinesulfinato-O)cobalt(III)

The first O-bonded sulfenate species [Co(en)2(py-SO-O)]2+ has been synthesized by isomerization of its S-bonded linkage isomer, [Co(en)2(pyridine-2-sulfenate-S]2+. The sulfenate ion in both forms is stabilized by coordination to the electropositive cobalt(III) ion. The driving force for the formation of the O-bonded sulfenate linkage isomer comes from the four to five membered ring expansion which accompanies the rearrangement. Crystal structures of the green O-sulfenate confirm the formulation and reveal varying amounts of a cocrystallized O-bonded sulfinate diastereomer. The cations have essentially identical structures except for the extra oxygen in the O-sulfinate. Differences in packing of cations and perchlorates give rise to two different structural types for the salts, corresponding to sulfenate-rich and sulfinate-rich phases.     

Synthesis and crystal structure of tris(ethylenediamine)cobalt(III) bis(tetrachloroaurate(III)) chloride

The binary complex salt [Co(N₂C₂H₈)₃][AuCl₄]₂Cl has been synthesized. Its crystal structure has been determined. Crystal data for C₆H₂₄N₆Cl₉AuCo: a = 20.8976(14) Å, b = 14.4773(9) Å, c = 7.9944(5) Å; β = 110.809(2)°; V = 2260.9(3) ų, space group C2/c, Z = 4, d _calc = 2.798 g/cm³. The plane square environment of the gold atom of the complex anion is completed to a tetragonal pyramid by the chlorine atom of the neighboring complex anion (Au…Cl 3.538 Å). The structure is layered. Layers of complex cations and complex anions alternate along the X axis.     

Structure of tetrakis(pyridinioacetate) neodymium(III) tetrahydrate perchlorate

The structure of tetrakis(pyridinioacetate) neodymium(III) tetrahydrate perchlorate, [Nd(pyBET)₄ · 4H₂O](ClO₄)₃, is reported. The neodymium atom is eight-coordinate dodecahedrally distorted polyhedron. The molecule consists of discrete [Nd(pyBET)₄ · 4H₂O]³⁺ cation and perchlorate anions held by ionic electrostatic force.