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Topic: Formation Constant for Isothiocyanatoiron(III) ion  (Read 18775 times)

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Offline richard

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Formation Constant for Isothiocyanatoiron(III) ion
« on: July 30, 2007, 08:42:49 PM »
Is there a known value for the formation constant of [FeNCS]2+?  The equilibrium equation is Fe3+ + NCS- <==> FeNCS2+.

Offline Borek

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Re: Formation Constant for Isothiocyanatoiron(III) ion
« Reply #1 on: July 31, 2007, 02:43:11 AM »
Fe3+ + SCN- <-> FeSCN2+; log K = 3.02
Fe3+ + 2SCN- <-> Fe(SCN)2+; log K = 4.64
Fe3+ + 3SCN- <-> Fe(SCN)3; log K = 5.0
Fe3+ + 4SCN- <-> Fe(SCN)4-; log K = 6.3
Fe3+ + 5SCN- <-> Fe(SCN)52-; log K = 6.2
Fe3+ + 6SCN- <-> Fe(SCN)63-; log K = 6.1


Edit: Sorry, after pasting the data I realized you asked about isothio... No idea where to find them.
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Offline AWK

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Re: Formation Constant for Isothiocyanatoiron(III) ion
« Reply #2 on: July 31, 2007, 03:26:01 AM »
SCN- anion forms mainly tiocyanate complexes. Only in crystals sometimes mixed complexes FeSCN and FeNCS happen
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