Andrew W. Zanella

Synthesis and Properties of Organo-Cyanoborane Complexes of Pentaamminecobalt(III)

Abstract Organo-cyanoborane ligands of formula R-BH2‒C˭N (R is trimethylamine, pyridine, or triphenylphosphine) have been shown to displace the CF3SO3 anion from trifluoromethanesulfonatopentaamminecobalt(III) cations in acetone to yield the respective nitrile complexes. These new cyanoborane complexes have been characterized via elemental analysis and by IR, visible and NMR spectroscopy. The reactions of these complexes in aqueous base and attempts to aminate the cyanide group in liquid ammonia will be described. The synthesis of some analogous alkyl nitrile complexes is described as well as the kinetics of their hydration reactions in basic media.

Determination of molar refractions and Abraham descriptors for tris(acetylacetonato)chromium(III), tris(acetylacetonato)iron(III) and tris(acetylacetonato)cobalt(III)

We have determined molar refractions of tris(acetylacetonato)chromium(III), tris(acetylacetonato)iron(III) and tris(acetylacetonato)cobalt(III). Although the d-electron structures of the three metal centres differ significantly, the three molar refractions are actually quite close to each other. We then used these molar refractions to determine the Abraham E-descriptor, we calculated the V-descriptor by McGowans method, and then used literature data on solubilities and water–solvent partitions to obtain the rest of the set of descriptors for the three tris(acetylacetonato) complexes. If we take E as the average of those for the chromium, iron and cobalt complexes, we can use limited literature data to obtain the full set of Abraham descriptors for the tris(acetylacetonates) of vanadium(III), yttrium(III), samarium(III), lanthanum(III) and neodymium(III). For the eight complexes, the descriptors vary regularly with complex molecular weight. These show that the complexes are quite polarizable, have zero hydrogen-bond acidity and significant hydrogen bond basicity. From the sets of Abraham descriptors, a very large number of physicochemical properties can be predicted for the eight acetonylacetonates.

IN MEMORIAM-ALAN McLEOD SARGESON (1930–2008)

Alan McLeod Sargeson passed away on December 29, 2008, at the age of 78. Alan made highly fundamental contributions to the synthesis, mechanistic behavior, structure and stereochemistry of coordination compounds. In many ways, his work contributed to a ‘‘coming of age’’ for inorganic chemistry, as mechanistic pathways distinct from those in organic chemistry were established. The extensive list of his accomplishments, many of which we include here, comprise a number of phenomena which we take for granted today. Alan and his coworkers unequivocally established the conjugate base mechanism for base hydrolysis of Co(III) complexes through a series of elegant experiments, including competition of added anions. These were a beautiful complement to the classic OH2= OH2 competition experiments of Green and Taube. He was one of the first inorganic chemists to appreciate the utility of NMR methods in 1 and ANDREW ZANELLA

A Simple Method for Producing a Mixture of Gaseous HCl and DCl for Measuring their Vibrational-Rotational Spectra

This article describes a simple, inexpensive, and rapid method for generating a mixture of DCl and HCl. We include infrared vibrational-rotational spectroscopy of gaseous hydrogen chloride and its deuterium counterpart in our physical chemisrty laboratory.

Base hydrolyses of penta-ammineruthenium(III) complexes of organonitriles

Base hydrolysis of the Ru(NH3)53+ complex of acetonitrile to the corresponding complex of the acetamide anion occurs with a rate ca. 108 as fast as the free ligand, ca. 106 as fast as the analogous RuII complex, and more than 102 faster than the RhIII analogue.