Association Involving Optically Active Ions. II. Association Constants of Tris(ethylenediamine)cobalt(III) and Tris(propylenediamine)-cobalt(III) Ions with Some Anions

Association constants of [Co en3]3+ (en=ethylenediamine) and d- and l-[Co d-pn3]3+ (pn=propylenediamine; d- and l- refer to the sign of optical rotation at sodium D-line) with some anions have been determined spectrophotometrically. Values are as follows: [Co en3]3+·SO42−49, [Co-en3]3+·glycollate− ∼5, d-[Co d-pn3]3+·SO42− 70, d-[Co d-pn3]3+·d-tart2− (tart2−=bivalent tartrate anion) 30, d-[Co d-pn3]3+·l-tart2− 28, l-[Co d-pn3]3+·SO42− 43, l-[Co d-pn3]3+·d-tart2− ∼7, l-[Co-d-pn3]3+·l-tart2− ∼16. These association constants are discussed in terms of the microscopic interaction between the ions. The effect of outer-sphere association on the circular dichroism and optical rotatory dispersion is also discussed.