| Popis: |
The title compound, Cs{sup +}[Co((3)-1,2-C{sub 2}B{sub 9}H{sub 11}){sub 2}]{sup {minus}}(CsCDC), was precipitated with a NaCDC solution from solutions containing CsCl. The reaction was followed by measuring loss of light intensity as the precipitate formed. The [Cs{sup +}] and [CDC{sup {minus}}] at the point of precipitation were estimated and approximate values of the K{sub sp} for CsCDC determined at room temperature: 8 {times} 10{sup {minus}6} (water), 7 {times} 10{sup {minus}6} (1 M NaOH), and 2 {times} 10{sup {minus}6} (5M NaCl/0.1 M KOH/1.0 M NaOH). In some cases, NaCDC precipitated from solution when added to the latter salt solution. For the medium, 5 M NaNO{sub 3}/0.1 M KOH/1.0 M NaOH a four-fold excess of NaCDC was added to a 10mM Cs{sup +} solution at 40{degrees}C and the [CDC{sup {minus}}] measured spectrophotometrically. Only CsCDC precipitated, and a K{sub sp} of 3.9 {times} 10{sup {minus}6} was determined. The solubilities of CsCDC were measured in NaNO{sub 3} and NaCl solutions at 30{sub C} as a function of the Na salt concentration. Reaction of the CDC{sup {minus}} with OH{sup {minus}} slowly produces B(OH{sub 4}{sup {minus}}, H{sub 2}, and CoO(OH). Reaction of 22 {mu}M CsCDC with 1M NaOH has a first order rate constant at 56{degrees}C of 8.8 {times} 10{sup {minus}7} s{sup {minus}1}, while that for 14 mM NaCDC is 7.2 {times} 10{sup {minus}7} s {sup {minus}1}. Activation energy for the reaction is 110 kJ. |
