Polyselenide anion speciation in aqueous solution has been investigated by electrospray mass spectrometry (ESMS). Two methods of control over this speciation are reported: countercation substitutions and pH adjustments. The countercation has been found to affect the degree of disproportionation or comproportionation. Solutions of sodium tetraselenide displayed numerous Se n 2and HSe n -species in neutral and basic soluions. In potassium solutions, the dominant species was Se 4 2-‚H 2 O. Solutions of cesium pentaselenide also showed preference for higher-order polyselenides. The pH dependence has been analyzed in terms of the percent Se n (n ) 2-5) present. Di-, tri-, tetra-, and pentaselenide species were present over the entire pH range investigated, and trends in selenide species versus pH were developed. For example, at pH > 9, tetraselenide species were dominant.

Carbon monoxide, although widely known as a toxic gas, has received great attention in the past few decades due to its promising role as a medical gas. Several classes of carbon monoxide releasing molecules (CORMs) have been synthesised with many of them having pharmacological activities under physiological conditions. Herein, we report the synthesis and structural characterization of the first example of amine carboxyborane that releases CO under physiological conditions without the aid of inducers. A representative compound hexamethylenetetramine carboxyborane (HMTA-CB) described here has a half-life of 2.7 days and gradually releases CO with the rate constant of 3.0 × 10 s. Its ability to promote cell growth shows the beneficial effect of slow CO release to supplement CO in small amounts over time.

Single-crystalline samples of Ca 2 NF were prepared by heating a stoichiometric mixture of Ca metal and CaF 2 under N 2 to 10003 3C, followed by slow cooling from the melt. The resulting Ca 2 NF crystals were yellow in color, and highly air-sensitive. A single-crystal X-ray di4raction analysis indicated that the compound is isostructural with L-Mg 2 NF, with tetragonal cell parameters a ‫؍‬ 4.9018(9) A s and c ‫؍‬ 10.516(3) A s , Z ‫؍‬ 4, and space group I4 1 /amd (No. 141). X-ray re5nement was carried out by full-matrix least-squares on F 2 on all data, to give R 1 ‫؍‬ 0.0426 (all data) and wR 2 ‫؍‬ 0.0630 for 12 parameters and 101 independent re6ections. The 5nal position assignments were analyzed via bond valence sum calculations. Academic Press