Diastereomeric D-1,4,7,10-tetrakis((R)-2-hydroxy-2-phenylethyl)-1,4,7,10-tetraazacyclododecane and Its Alkali-Metal Complex Ions. A Potentiometric Titration, Nuclear Magnetic Resonance, and Molecular Orbital Study
| dc.contributor.author | Whitbread, S. | |
| dc.contributor.author | Valente, P. | |
| dc.contributor.author | Buntine, M. | |
| dc.contributor.author | Clements, P. | |
| dc.contributor.author | Lincoln, S. | |
| dc.contributor.author | Wainwright, K. | |
| dc.date.issued | 1998 | |
| dc.description | © 1998 American Chemical Society | |
| dc.description.abstract | <sup>13</sup>C NMR studies are consistent with Δ-1,4,7,10-tetrakis((R)-2- hydroxy-2-phenylethyl)-l,4,7,10tetraazacyclododecane (ΔR-thpec 12) and its eight-coordinate alkali-metal complexes, Δ[M(R-thpec 12)]<sup>+</sup>, existing predominantly as single square antiprismatic Δ diastereomers in dimethylformamide. Molecular orbital calculations show the parallel square oxygen and nitrogen planes to delineate the square antiprismatic structure of ΔR-thpec12 and Δ[M(R-thpec12)]<sup>+</sup> where the basket defined by the four phenyl groups of ΔR-thpec12 becomes increasingly shallow as the M<sup>+</sup> radius increases from Na<sup>+</sup> to Cs<sup>+</sup> and the four oxygens move further apart. An intramolecular exchange process, involving double inversion of all four nitrogen centers, occurs in ΔR-thpec12 for which k(298.2 K) = 46300 ± 1800 s<sup>-1</sup>, ΔH(+) = 40.8 ± 0.4 kJ mol<sup>-1</sup>, and ΔS(+) = -18.8 ± 1.7 J K<sup>-1</sup> mol<sup>-1</sup>. In [M(R-thpec12)]<sup>+</sup> this process is characterized by k(298.2 K) = 233 ± 2, 98 ± 1, 4900 ± 100, 33500 ± 1000, and 34500 ± 1100 s<sup>-1</sup>, ΔH(+) = 34.6 ± 0.3, 46.1 ± 0.2, 42.7 ± 0.3, 39.1 ± 0.3, and 38.5 ± 0.3 kJ mol<sup>-1</sup>, and ΔS(+) = -83.5 ± 1.1, -52.2 ± 0.7, -31.1 ± 1.2, -27.2 ± 1.2, and -28.9 ± 1.3 J K<sup>-1</sup> mol<sup>-1</sup>, respectively, when M<sup>+</sup> = Li<sup>+</sup>, Na<sup>,</sup> K<sup>+</sup>, Rb<sup>+</sup>, and Cs<sup>+</sup>. For intermolecular ligand exchange on Δ[M(Rthpec12)]<sup>+</sup>, decomplexation is characterized by k(d)(298.2 K) = 396 ± 3, 156 ± 3, and 152000 ± 6000 s<sup>-1</sup>, ΔH(d)(+) = 46.0 ± 0.3, 62.3 ± 0.5, and 69.8 ± 0.5 kJ mo1<sup>-1</sup>, and ΔS(d)(+) = -40.9 ± 1.0, 6.0 ± 1.9, and 88.4 ± 2.1 J K<sup>-</sup> <sup>1</sup> mol<sup>-1</sup>, respectively, when M<sup>+</sup> = Li<sup>+</sup>, Na<sup>+</sup>, and K<sup>+</sup>. The stability constant, K, of Δ[M(R-thpec 12)]<sup>+</sup> varies as M<sup>+</sup> changes in the sequence Li<sup>+</sup> (3.13 ± 0.05), Na<sup>+</sup> (4.25 ± 0.05), K<sup>+</sup> (4.10 ± 0.05), Rb<sup>+</sup> (3.57 ± 0.05), Cs<sup>+</sup> (3.47 ± 0.05), and Ag<sup>+</sup> (8.14 ± 0.03), where the figures in parentheses are 1og(K/(dm<sup>3</sup> mol<sup>+1</sup>)) determined in dimethylformamide by potentiometric titration at 298.2 K and I = 0.05 mol dm<sup>-3</sup> (NEt<inf>4</inf>ClO<inf>4</inf>). | |
| dc.description.statementofresponsibility | Sonya L. Whitbread, Peter Valente, Mark A. Buntine, Philip Clements, Stephen F. Lincoln, and Kevin P. Wainwright | |
| dc.identifier.citation | Journal of the American Chemical Society, 1998; 120(12):2862-2869 | |
| dc.identifier.doi | 10.1021/ja973367l | |
| dc.identifier.issn | 0002-7863 | |
| dc.identifier.issn | 1520-5126 | |
| dc.identifier.uri | http://hdl.handle.net/2440/4638 | |
| dc.language.iso | en | |
| dc.publisher | AMER CHEMICAL SOC | |
| dc.source.uri | https://doi.org/10.1021/ja973367l | |
| dc.title | Diastereomeric D-1,4,7,10-tetrakis((R)-2-hydroxy-2-phenylethyl)-1,4,7,10-tetraazacyclododecane and Its Alkali-Metal Complex Ions. A Potentiometric Titration, Nuclear Magnetic Resonance, and Molecular Orbital Study | |
| dc.type | Journal article | |
| pubs.publication-status | Published |