UV/VIS Laser Photochemistry: Intermediary Formation of Diazoalkanes versus Direct S0,T1 Transitions in the Photolysis of Azoalkanes
✍ Scribed by Prof. Dr. Waldemar Adam; Dipl.-Chem. Markus Dörr; Dipl.-Chem. Peter Hössel
- Publisher
- John Wiley and Sons
- Year
- 1986
- Tongue
- English
- Weight
- 257 KB
- Volume
- 25
- Category
- Article
- ISSN
- 0044-8249
No coin nor oath required. For personal study only.
✦ Synopsis
bonded in 3, is C.0-bonded in 4.I5l At first sight, the isomerization that occurs upon reductive carbonylation of 3 is surprising, because the sterically demanding phenyl substituents are thereby placed in closer proximity to the metal center and to the terminal ligands; however, it may be understood by taking into consideration the greater electron density on Re"'. The metal in 4 is coordinated in a (very distorted) square-pyramidal fashion ; the metallacycle (sum of angles 358") is only slightly bent along the C4. . -0 4 vector (164.6"). Upon reduction of 3 to 4, the mirror plane is lost.
["] Under CO pressure, the Re" complex 5 is also reduced. In this case, too, the deoxygenation gives exclusively the Re"' derivative 6, but without isomerization of the N,Oimidocarboxylato ligand. The carbonylation of 7 under pressure leads stereoselectively to the trans isomer of the compound 8, which until now was only accessible in admixture with the cis isomer.'71 Besides carbon monoxide, carbonyltitanium reagents are also suitable for the deoxygenating carbonylation of Re" and Re"" complexes of the class of compounds discussed here. Thus, reaction of 1 with 9 affords mainly the Re" derivative 10 (> 80%) along with a small amount of 11.