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Zinc thiolate complexes ZnLn(SR)(+) with azamacrocyclic ligands, part II: Mechanism of the reaction with CS2

Notni, J. and Schenk, S. and Roth, A. and Plass, W. and Gorls, H. and Uhlemann, U. and Walter, A. and Schmitt, M. and Popp, J. and Chatzipapadopoulos, S. and Emmler, T. and Breitzke, H. and Leppert, J. and Buntkowsky, G. and Kempe, K. and Anders, E. (2006):
Zinc thiolate complexes ZnLn(SR)(+) with azamacrocyclic ligands, part II: Mechanism of the reaction with CS2.
In: European Journal of Inorganic Chemistry, pp. 2783-2791, (14), [Online-Edition: http://apps.webofknowledge.com/full_record.do?product=WOS&se...],
[Article]

Abstract

The thiolate complexes Zn(15]aneN(4))(S-CH2-C6H5)]ClO4 (1) (15aneN(4) = 1,4,8,12-tetraazacyclopentadecane) and Zn(i-14]aneN(4))(S-CH2-C6H5)ICIO4 (2) (i-14aneN(4) = 1, 4,7, 11 -tetraazacyclotetradecane) have been reacted with carbon disulfide. The trithiocarbonate complexes Zn(15]aneN(4))S-C(S)-S-CH2-C6H5]CIO4 1a, monoclinic, space group P2(1)/n, Z = 8, a = 13,2338(1) angstrom, b = 12.9251(2) angstrom, c = 30.1669(4) angstrom, beta = 101.463(1)degrees, V = 5057.1(1) angstrom(3) and Zn(i14]aneN(4))S-C(S)-S-CH2-C6H5]CIO4 2a, orthorhombic, space group P2(1)2(1)2(1), Z = 8, a = 9.9936(1) angstrom, b 22.1261(4) angstrom, c = 22.3192(4) angstrom, V = 4935.2(l) angstrom(3) were obtained. The reaction of 1 with CS2 is second order with a rate constant of k = (57.6 +/- 2.4) x 10(-3) m(-1.)s(-1) at 25 degrees C. The experimentally determined Eyring activation barrier is Delta H-exp(double dagger) = 65.3 +/- 0.7 kJ(.)mol(-1) (Delta S-exp(double dagger) = -49.9 +/- 2.5 J(.)mol(-1.)K(-1)) and a free energy of activation of Delta G* = 80.2 +/- 1.5 kJ(.)mol(-1) at 25 degrees C. To discriminate between an associative and a dissociative mechanism the barriers for both processes were calculated using density functional theory at the C-PCM(B98/G3MP2Large)//B3LYP/ 6-311+G(d) level. The associative mechanism is clearly favored with a difference in free energies of activation of delta Delta G(double dagger) approximate to 80kJ(.)mol(-1). Its calculated barrier Delta G(theor)(double dagger) = 114.3 kJ(.)mol(-1) is in reasonable agreement with the experimental value. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006).

Item Type: Article
Erschienen: 2006
Creators: Notni, J. and Schenk, S. and Roth, A. and Plass, W. and Gorls, H. and Uhlemann, U. and Walter, A. and Schmitt, M. and Popp, J. and Chatzipapadopoulos, S. and Emmler, T. and Breitzke, H. and Leppert, J. and Buntkowsky, G. and Kempe, K. and Anders, E.
Title: Zinc thiolate complexes ZnLn(SR)(+) with azamacrocyclic ligands, part II: Mechanism of the reaction with CS2
Language: English
Abstract:

The thiolate complexes Zn(15]aneN(4))(S-CH2-C6H5)]ClO4 (1) (15aneN(4) = 1,4,8,12-tetraazacyclopentadecane) and Zn(i-14]aneN(4))(S-CH2-C6H5)ICIO4 (2) (i-14aneN(4) = 1, 4,7, 11 -tetraazacyclotetradecane) have been reacted with carbon disulfide. The trithiocarbonate complexes Zn(15]aneN(4))S-C(S)-S-CH2-C6H5]CIO4 1a, monoclinic, space group P2(1)/n, Z = 8, a = 13,2338(1) angstrom, b = 12.9251(2) angstrom, c = 30.1669(4) angstrom, beta = 101.463(1)degrees, V = 5057.1(1) angstrom(3) and Zn(i14]aneN(4))S-C(S)-S-CH2-C6H5]CIO4 2a, orthorhombic, space group P2(1)2(1)2(1), Z = 8, a = 9.9936(1) angstrom, b 22.1261(4) angstrom, c = 22.3192(4) angstrom, V = 4935.2(l) angstrom(3) were obtained. The reaction of 1 with CS2 is second order with a rate constant of k = (57.6 +/- 2.4) x 10(-3) m(-1.)s(-1) at 25 degrees C. The experimentally determined Eyring activation barrier is Delta H-exp(double dagger) = 65.3 +/- 0.7 kJ(.)mol(-1) (Delta S-exp(double dagger) = -49.9 +/- 2.5 J(.)mol(-1.)K(-1)) and a free energy of activation of Delta G* = 80.2 +/- 1.5 kJ(.)mol(-1) at 25 degrees C. To discriminate between an associative and a dissociative mechanism the barriers for both processes were calculated using density functional theory at the C-PCM(B98/G3MP2Large)//B3LYP/ 6-311+G(d) level. The associative mechanism is clearly favored with a difference in free energies of activation of delta Delta G(double dagger) approximate to 80kJ(.)mol(-1). Its calculated barrier Delta G(theor)(double dagger) = 114.3 kJ(.)mol(-1) is in reasonable agreement with the experimental value. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006).

Journal or Publication Title: European Journal of Inorganic Chemistry
Number: 14
Uncontrolled Keywords: zinc macrocyclic ligands enzyme models heterocumulenes density functional calculations carbonyl sulfide cos density functionals catalytic cycle test set model anhydrase exchange energies consumption gaussian-3
Divisions: 07 Department of Chemistry
07 Department of Chemistry > Physical Chemistry
Date Deposited: 27 Oct 2014 20:47
Official URL: http://apps.webofknowledge.com/full_record.do?product=WOS&se...
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067HL Times Cited:10 Cited References Count:37

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