Summary
The Co(NH3)5[OC(NH2)2]3+ cation in aqueous acid reacts with chlorine and hypochlorous acid, with two sequential steps observed in each case. Rate constants for both steps show a first-order dependence on [oxidant], with k1/k2 always <20, but varying with the choice of reactant and acid. Rate constants with Cl2 as reactant are faster than with HOCl, possibly related to preferential attack by Cl+ compared with OCl− on the bound urea. Competition by ions (HSO −4 , Cl− or NO −3 ) measured by product analysis of reactions conducted in 1 M acid produced competition ratios R (R=[CoX]/[CoOH2][X]) which are similar to values determined with a range of leaving groups previously, indicating a mechanistic constancy. No formation of Co(NH3)5Cl2+ was observed in reactions conducted in H2SO4 or HNO3, implying that free Cl− is not generated at the reaction site and captured by the metal ion. Electronic and vibrational spectra of the intermediate formed in the two stage reaction is indicative of a change from an O-bound to an N-bound ligand in forming that intermediate, although it cannot be a simple isomerization due to the dependence on [oxidant]. A possible mechanism is discussed.
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References
R. K. Andrews, R. L. Blakeley and B. Zerner,Adv. Inorg. Biochem., 6, 245 (1984).
R. T. Morrison and R. N. Boyd,Organic Chemistry, Allyn and Bacon, Boston, 1959, p. 693.
A. E. Werner (Ed.),Chemistry of Urea, Longmans, Green and Co., London, 1923.
P. Sykes,A Guidebook to Mechanism in Organic Chemistry, 2nd Edit., Longmans, Green and Co., London, 1965, p. 93.
A. Haim and H. Taube,J. Am. Chem. Soc., 85, 3108 (1963).
J. F. Remar, D. E. Pennington and A. Haim,Inorg. Chem. 4, 1832 (1965).
J. MacB. Harrowfield, A. M. Sargeson, B. Singh and J. C. Sullivan,Inorg. Chem., 14, 2864 (1975).
W. G. Jackson and A. M. Sargeson,Inorg. Chem., 15, 1986 (1976).
A. Haim and H. Taube,Inorg. Chem., 2, 1199 (1963); F. A. Posey and H. Taube,J. Am. Chem. Soc., 79, 255 (1957).
W. L. Reynolds and E. R. Alton,Inorg. Chem., 17, 3355 (1978).
D. A. Buckingham, I. I. Olsen, A. M. Sargeson and H. Satrapa,Inorg. Chem., 6, 1027 (1967).
W. G. Jackson, G. A. Lawrance and A. M. Sargeson,Inorg. Chem., 19, 1001 (1980).
G. Zimmerman and F. C. Strong,J. Am. Chem. Soc., 79, 2063 (1957).
N. E. Dixon, W. G. Jackson, W. Marty and A. M. Sargeson,Inorg. Chem., 21, 688 (1982); W. G. Jackson and C. N. Hookey,Inorg. Chem., 23, 668 (1984).
W. G. Jackson, C. N. Hookey, M. L. Randall, P. Comba and A. M. Sargeson,Inorg. Chem., 23, 2473 (1984).
N. J. Curtis, G. A. Lawrance and A. M. Sargeson,Amt. J. Chem., 36, 1495 (1983).
N. E. Dixon, D. P. Fairlie, W. G. Jackson and A. M. Sargeson,Inorg. Chem., 22, 4038 (1983).
N. J. Curtis, N. E. Dixon and A. M. Sargeson,J. Am. Chem. Soc., 105, 5347 (1983).
I. I. Olsen and J. Bjerrum,Acta Chem. Scand., 21, 1112 (1967); F. A. Posey and H. Taube,J. Am. Chem. Soc., 78, 15 (1956); T. Taura and H. Yoneda,Inorg. Chem., 17, 1495 (1978).
W. G. Jackson, G. A. Lawrance and A. M. Sargeson, unpublished results.
N. E. Dixon, W. G. Jackson, M. A. Lancaster, G. A. Lawrance and A. M. Sargeson,Inorg. Chem., 20, 470 (1981).
A. A. Frost and R. G. Pearson,Kinetics and Mechanisms, 2nd Edit., Wiley, London, 1961.
W. G. Jackson, J. MacB. Harrowfield and P. D. Vowles,Int. J. Chem. Kinet., 9, 535 (1977); W. G. Jackson and A. M. Sargeson,Inorg. Chem., 17, 1348 (1978).
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Lawrance, G.A. Reaction of pentaammine(urea-O)cobalt(III) cation with chlorine and hypochlorous acid in aqueous solution. Transition Met Chem 11, 396–399 (1986). https://doi.org/10.1007/BF01225991
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DOI: https://doi.org/10.1007/BF01225991