Organorhenium chemistry describes the compounds with Re−C bonds. Becauserhenium is a rare element, relatively few applications exist, but the area has been a rich source of concepts and a few usefulcatalysts.
Rhenium exists in ten known oxidation states from −3 to +7 except −2, and all but Re(−3) are represented by organorhenium compounds. Most are prepared from salts ofperrhenate and related binary oxides.[1] The halides, e.g.,ReCl5 are also useful precursors as are certain oxychlorides.
A noteworthy feature of organorhenium chemistry is the coexistence of oxide and organic ligands in the samecoordination sphere.[2]
One of the firsttransition metal hydride complexes to be reported was (C5H5)2ReH. A variety ofhalf-sandwich compounds have been prepared from (C5H5)Re(CO)3 and (C5Me5)Re(CO)3. Notable derivatives include theelectron-precise oxide (C5Me5)ReO3 and (C5H5)2Re2(CO)4.
Rhenium forms a variety of alkyl and aryl derivatives, often with pi-donor coligands such as oxo groups. Well known ismethylrhenium trioxide ("MTO"), CH3ReO3 a volatile, colourless solid, a rare example of a stable high-oxidation state metal alkyl complex. This compound has been used as acatalyst in some laboratory experiments. It can be prepared by many routes, a typical method is the reaction of Re2O7 andtetramethyltin:[7]
Re2O7 + (CH3)4Sn → CH3ReO3 + (CH3)3SnOReO3
Analogous alkyl and aryl derivatives are known. Although PhReO3 is unstable and decomposes at –30 °C, the corresponding sterically hindered mesityl and 2,6-xylyl derivatives (MesReO3 and 2,6-(CH3)2C6H3ReO3) are stable at room temperature. The electron poor 4-trifluoromethylphenylrhenium trioxide (4-CF3C6H4ReO3) is likewise relatively stable.[8] MTO and other organylrhenium trioxides catalyze oxidation reactions withhydrogen peroxide as well as olefin metathesis in the presence of a Lewis acid activator.[9] Terminalalkynes yield the corresponding acid or ester, internal alkynes yield diketones, andalkenes give epoxides. MTO also catalyses the conversion ofaldehydes anddiazoalkanes into an alkene.[10]
Rhenium is also able to make complexes withfullerene ligands such as Re2(PMe3)4H8(η2:η2C60).
Synthesis of Organometallic Compounds: A Practical Guide Sanshiro Komiya Ed. S. Komiya, M. Hurano 1997.
Pericles Stavropoulos, Peter G. Edwards, Geoffrey Wilkinson, Majid Motevalli, K. M. Abdul Malik and Michael B. Hursthouse "Oxoalkyls of rhenium-(V) and-(VI). X-Ray crystal structures of (Me4ReO)2Mg(thf)4,[(Me3SiCH2)4ReO]2Mg(thf)2, Re2O3Me6 and Re2O3(CH2SiMe3)6" J. Chem. Soc., Dalton Trans., 1985, pp. 2167-2175.doi:10.1039/DT9850002167
^O. Glemser "Ammonium Perrhenate" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 1476-85.
^Lazarova, N.; James, S.; Babich, J.; Zubieta, J. (2004). "A convenient synthesis, chemical characterization and reactivity of [Re(CO)3(H2O)3]Br: the crystal and molecular structure of [Re(CO)3(CH3CN)2Br]".Inorganic Chemistry Communications.7 (9):1023–1026.doi:10.1016/j.inoche.2004.07.006.
^Alberto, R.; Egli, A.; Abram, U.; Hegetschweiler, K.; Gramlich V.; Schubiger, P. A. (1994). "Synthesis and reactivity of [NEt4]2[ReBr3(CO)3]. Formation and structural characterization of the clusters [NEt4][Re3(µ3-OH)(µ-OH)3(CO)9] and [NEt4][Re2(µ-OH)3(CO)6] by alkaline titration".J. Chem. Soc., Dalton Trans. (19):2815–2820.doi:10.1039/DT9940002815.
^Romão, Carlos C.; Kühn, Fritz E.; Herrmann, Wolfgang A. (1997). "Rhenium(VII) Oxo and Imido Complexes: Synthesis, Structures, and Applications".Chemical Reviews.97 (8):3197–3246.doi:10.1021/cr9703212.PMID11851489.
^Dyckhoff, Florian; Li, Su; Reich, Robert M.; Hofmann, Benjamin J.; Herdtweck, Eberhardt; Kühn, Fritz E. (2018). "Synthesis, characterization and application of organorhenium(vii) trioxides in metathesis reactions and epoxidation catalysis".Dalton Transactions.47 (29):9755–9764.doi:10.1039/c8dt02326c.ISSN1477-9226.PMID29987275.
^Schmidt, Boris (1997). "Methyltrioxorhenium - from oxidation and cyclopropanation to metathesis".Journal für Praktische Chemie/Chemiker-Zeitung.339 (1):493–496.doi:10.1002/prac.19973390190.ISSN0941-1216.
^Hudson, A. "Methyltrioxorhenium" Encyclopedia of Reagents for Organic Synthesis. John Wiley & Sons: New York, 2002.
