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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 30, Number 4
JKCSEZ 30(4)
August 20, 1986 

Pressure Effects on the Ionic Dissociation of [Co(en)3]Cl3 and [Co(NH3)6]Cl3 in Aqueous Solutions

수용액에서 [Co(en)3]Cl3 및 [Co(NH3)6]Cl3 착물의 이온 해리에 미치는 압력의 영향
Jong-Jae Chung, Byung-Cill Rho

정종재, 노병길
25℃에서 [Co(en)3]Cl3, [Co(NH3)6]Cl3 수용액의 열역학적 해리상수를 1~2000bar의 압력범위에서 전도도법으로 측정하였다. 착물이 해리할 때 하전을 띤 이온이 생성하여 부피가 감소하므로 압력이 증가함에 따라 해리상수(KT)는 커졌다. 즉 [Co(en)3]Cl3에 대한 pKT값은 1bar에서 2.16, 500bar에서 2.08, 1000bar에서 2.08, 1500bar에서 2.05, 2000bar에서 2.03이었고, [Co(NH3)6]Cl3의 pKT는 1bar에서 2.02, 500bar에서 1.96, 1000bar에서 1.90, 1500bar에서 1.88, 2000bar에서는 1.87이었다. 각 압력에서 Stokes반경과 해리상수(KT)값을 비교 분석하여 착물의 이온쌍 형성에는 정전기적 인력 이외에 Internal Conjugate Base(ICB)효과도 영향을 미쳤으며 이효과는 압력이 증가할 수록 커졌다.

The thermodynamic dissociation constants of [Co(en)3]Cl3 and [Co(NH3)6]Cl3 in aqueous solutions at 25℃ and at the pressure from 1 bar to 2000 bars were measured by conductometric method. The dissociation constants were increased with pressure elevation because of volume decreasing by the formation of charged ions during dissociation reaction. That is, the pKT values of [Co(en)3]Cl3 were 2.16 for I bar, 2.08 for 500 bars, 2,08 for 1000 bars, 2.05 for 1500 bars and 2.03 for 2000 bars, respectively and those of [Co(NH3)6]Cl3 were 2.02 for 1 bar 1.96 for 500 bars, 1.90 for 1000 bars, 1. 88 for 1500 bars and 1. 87 for 2000 bars, respectively. Comparing and analyzing the values of Stokes' radii and KT, the formation of ion pair compound was affected by not only the electrostatic interaction, but also the Interal Conjugate Base(ICB), which was increased by the elevation of the pressure.

335 - 340
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