Hydrolysis of the Organometallic Aqua Ion fac-Triaquatricarbonylrhenium(I). Mechanism, pKa, and Formation Constants of the Polynuclear Hydrolysis Products
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- 作者：André ; Egli ; Kaspar Hegetschweiler ; Roger Alberto ; Ulrich Abram ; Roger Schibli ; Roman Hedinger ; Volker Gramlich ; Reinhard Kissner ; and P. August Schubiger
- 刊名：Organometallics
- 出版年：1997
- 出版时间：April 29, 1997
- 年：1997
- 卷：16
- 期：9
- 页码：1833 - 1840
- 全文大小：225K
- 年卷期：v.16,no.9(April 29, 1997)
- ISSN：1520-6041
文摘
Hydrolytic pathways of the organometallic aqua ion[Re(CO)3(H2O)3]+(2) in aqueous mediawere investigated by means of potentiometric titration experiments.The aqua complex 2was obtained quantitatively by dissolving(NEt4)2[Re(CO)3Br3](1) in water. Conventionalalkalimetric titrations (0.1 M KNO3, 25 
C) allowed thedetermination of the formationconstants of[Re3(CO)9(
2-OH)3(3-OH)]-(3) and[Re2(CO)6(2-OH)3]-(4). The neutraldinuclear[Re2(CO)6(2-OH)2(H2O)2](5) was observed as a minor species. A fasttitrationtechnique was used to investigate a rapid preequilibrium, consisting ofthe formation of themononuclear deprotonation products[Re(CO)3(OH)(H2O)2](6) and[Re(CO)3(OH)2(H2O)]-(7).The corresponding pKa values are7.5(2) and 9.3(3). The immediate extraction of anaqueoussolution of 2 with diethyl ether after base addition (1equiv) led to the quantitative isolationof the well-known cubane cluster[Re(CO)3(OH)]4 (8),which was obtained as a DMF (8b) orOPPh3 adduct (8c). Attempts to isolate theaqua complex 2 as a crystalline material byprecipitating the bromo ligands of 1 withAgCF3COO resulted in the formation of(NEt4)2[Re(CO)3(CF3COO)3](9). The structures of 8b, 8c,and 9 were elucidated by single-crystal X-ray analysis.
C) allowed thedetermination of the formationconstants of[Re3(CO)9(2-OH)3(3-OH)]-(3) and[Re2(CO)6(2-OH)3]-(4). The neutraldinuclear[Re2(CO)6(2-OH)2(H2O)2](5) was observed as a minor species. A fasttitrationtechnique was used to investigate a rapid preequilibrium, consisting ofthe formation of themononuclear deprotonation products[Re(CO)3(OH)(H2O)2](6) and[Re(CO)3(OH)2(H2O)]-(7).The corresponding pKa values are7.5(2) and 9.3(3). The immediate extraction of anaqueoussolution of 2 with diethyl ether after base addition (1equiv) led to the quantitative isolationof the well-known cubane cluster[Re(CO)3(OH)]4 (8),which was obtained as a DMF (8b) orOPPh3 adduct (8c). Attempts to isolate theaqua complex 2 as a crystalline material byprecipitating the bromo ligands of 1 withAgCF3COO resulted in the formation of(NEt4)2[Re(CO)3(CF3COO)3](9). The structures of 8b, 8c,and 9 were elucidated by single-crystal X-ray analysis.