Water-exchange studies by oxygen-17 nuclear magnetic resonance on nickel(II) complexes with diethylenetriamine, triethylenetetramine, and tetraethylenepentamine
Oxygen-17 NMR studies were made on aqueous solutions containing Ni(dien)(H/sub 2/O)/sub 3//sup 2 +/, Ni(trien)(H/sub 2/O)/sub 2//sup 2 +/, and Ni(tetren)(H/sub 2/O)/sup 2 +/. The scalar coupling constants (A/h) based on the above formulas are 2.27 +- 0.04, 2.25+- 0.32, and 2.52 +- 0.03 x 10/sup 7/ Hz, respectively. T/sub 2//sub M/ values (transverse relaxation time for /sup 17/O bound to the metal ion) and temperature coefficients are given. The Ni-dien system shows at least two water-exchange rates which are not well resolved. Suggested parameters are as follows: two fast waters, k/sub l/ = 3 x 10/sup 6/ s/sup -1/, ..delta..H/sup 2 +/ = 9 kcal/mol, ..delta..S/sup 2 +/ equals 2 eu; ''slow'' water, k/sub l/ = 4 x 10/sup 5/ s/sup -1/, ..delta..H/sup 2 +/ = 11 kcal/mole, ..delta..S/sup 2 +/ approximately equal to 3 eu. For Ni-trien only one exchange rate is seen with k/sub l/ = (5.7 +- 1.6) x 10/sup 5/ s/sup -1/, ..delta..H/sup 2 +/ = 8.2 +- 0.9 kcal/mole, and ..delta..S/sup 2 +/ = -4.6 +- 3.6 eu. For Ni-tetren, k/sub l/ = (1.12 +- 0.22) x 10/sup 7/ s/sup -1/, ..delta..H/sup 2 +/ = 8.6 +- 0.7 kcal/mole, and ..delta..S/sup 2 +/ = 2.5 +- 2.5 eu. Comparisons with net substitution rates are made. (auth)
- Research Organization:
- Washington State Univ., Pullman
- OSTI ID:
- 7363445
- Journal Information:
- Inorg. Chem.; (United States), Journal Name: Inorg. Chem.; (United States) Vol. 15:4; ISSN INOCA
- Country of Publication:
- United States
- Language:
- English
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400201* -- Chemical & Physicochemical Properties
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AMINES
CHEMICAL REACTION KINETICS
COMPLEXES
COMPUTER CODES
COUPLING CONSTANTS
ENTHALPY
ENTROPY
EVEN-ODD NUCLEI
ISOTOPES
ISOTOPIC EXCHANGE
KINETICS
LIGHT NUCLEI
MAGNETIC RESONANCE
NICKEL COMPLEXES
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ORGANIC COMPOUNDS
OXYGEN 17
OXYGEN ISOTOPES
PHYSICAL PROPERTIES
REACTION KINETICS
RESONANCE
STABLE ISOTOPES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPLEXES