Tuning the Reactivity in Classic Low-Spin d6 Rhenium(I) Tricarbonyl Radiopharmaceutical Synthon by Selective Bidentate Ligand Variation (L,L鈥?/i>-Bid; L,L鈥?/i>= N,N鈥?/i>, N,O
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- 作者：Marietjie Schutte ; Gerdus Kemp ; Hendrik G. Visser ; Andreas Roodt
- 刊名：Inorganic Chemistry
- 出版年：2011
- 出版时间：December 19, 2011
- 年：2011
- 卷：50
- 期：24
- 页码：12486-12498
- 全文大小：499K
- 年卷期：v.50,no.24(December 19, 2011)
- ISSN：1520-510X
文摘
A range of fac-[Re(CO)3(L,L鈥?/i>-Bid)(H2O)]n (L,L鈥?/i>-Bid = neutral or monoanionic bidentate ligands with varied L,L鈥?/i> donor atoms, N,N鈥?/i>, N,O, or O,O鈥?/i>: 1,10-phenanthroline, 2,2鈥?/i>-bipydine, 2-picolinate, 2-quinolinate, 2,4-dipicolinate, 2,4-diquinolinate, tribromotropolonate, and hydroxyflavonate; n = 0, +1) has been synthesized and the aqua/methanol substitution has been investigated. The complexes were characterized by UV鈥搗is, IR and NMR spectroscopy and X-ray crystallographic studies of the compounds fac-[Re(CO)3(Phen)(H2O)]NO3路0.5Phen, fac-[Re(CO)3(2,4-dQuinH)(H2O)]路H2O, fac-[Re(CO)3(2,4-dQuinH)Py]Py, and fac-[Re(CO)3(Flav)(CH3OH)]路CH3OH are reported. A four order-of-magnitude of activation for the methanol substitution is induced as manifested by the second order rate constants with (N,N鈥?/i>-Bid) < (N,O-Bid) < (O,O鈥?/i>-Bid). Forward and reverse rate and stability constants from slow and stopped-flow UV/vis measurements (k1, M鈥? s鈥?; k鈥?, s鈥?; K1, M鈥?) for bromide anions as entering nucleophile are as follows: fac-[Re(CO)3(Phen)(MeOH)]+ (50 卤 3) 脳 10鈥?, (5.9 卤 0.3) 脳 10鈥?, 84 卤 7; fac-[Re(CO)3(2,4-dPicoH)(MeOH)] (15.7 卤 0.2) 脳 10鈥?, (6.3 卤 0.8) 脳 10鈥?, 25 卤 3; fac-[Re(CO)3(TropBr3)(MeOH)] (7.06 卤 0.04) 脳 10鈥?, (4 卤 1) 脳 10鈥?, 18 卤 4; fac-[Re(CO)3(Flav)(MeOH)] 7.2 卤 0.3, 3.17 卤 0.09, 2.5 卤 2. Activation parameters (螖Hk1, kJmol鈥?; 螖Sk1, J K鈥? mol鈥?) from Eyring plots for entering nucleophiles as indicated are as follows: fac-[Re(CO)3(Phen)(MeOH)]+ iodide 70 卤 1, 鈭?5 卤 3; fac-[Re(CO)3(2,4-dPico)(MeOH)] bromide 80.8 卤 6, 鈭? 卤 2; fac-[Re(CO)3(Flav)(MeOH)] bromide 52 卤 5, 鈭?2 卤 15. A dissociative interchange mechanism is proposed.