Distortional Isomers of [LWOCl2]+ in the Solid State and in Solution; Crystal Structures of the Blue and Green Forms of [LWOCl2]PF6

✍ Scribed by Prof. Dr. Karl Wieghardt; Dr. Gabriele Backes-Dahmann; Dr. Bernhard Nuber; Prof. Dr. Johannes Weiss

• Publisher: John Wiley and Sons
• Year: 1985
• Tongue: English
• Weight: 233 KB
• Volume: 24
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.198507771

✦ Synopsis

The blue and green crystals of the diamagnetic neutral complex cis-mer- [MoOCI,(PMe2Ph),lI'l exhibit so-called distortional isomerism. In each case, the Mo'" center is surrounded octahedrally by the monodentate ligands in identical spatial arrangement (cis-mer); in the solid state, the two forms differ only in the lengths of the Mo=O bond and the Mo-CI bond trans to the 0x0 group (Mo=O: 167.6(7) (blue), 180.3(11) pm (green); Mo-CI 255.1(3) and 242.6(6) pm, respectively). In solution, the green form is transformed irreversibly into the blue form. Wilkinson et al. have described analogous blue and green crystals of [MoOC12( PMe&], but did not characterize these as distortional isomers.'21 Recently, we were able to confirm the existence of this type of isomerism in the complex anions [PPh4],[MoO(CN),(H20)].4 H 2 0 (green) and [AsPh,],[MoO(CN),(H,O)]~ 4 H 2 0 (blue) by X-ray analysis. In this case, too, the blue form exhibits a shorter Mo=O bond than the green form. Salts of [MoO(CN),]~-ions also exist in blue and green forms.131 Common to all of these compounds is a Mo'"=O group, their diamagnetism, and the fact that, in solution, only one form prevails.