Is bond stretch isomerism in mononuclear transition metal complexes a real issue? The misleading case of the MoCl5/tetrahydropyran reaction systemCCDC 1042925-1042928 (1b-d) and 1042920-1042924 (2a-e). For crystallographic data in CIF or other electronic format see DOI: 10.1039/c5dt01378j

• Main Authors: Di Nicola, Francesco Paolo, Lanzi, Massimiliano, Marchetti, Fabio, Pampaloni, Guido, Zacchini, Stefano
• Format: Article
• Language: English
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c5dt01378j

Distinct batches of orange ( 1a-e ) and green crystals ( 2a-e ) were isolated from the reactions of MoCl 5 with tetrahydropyran (thp), respectively at room temperature (in CH 2 Cl 2 ) and at ca. 80 °C (in ClCH 2 CH 2 Cl). Crystals 2a-e are isomorphous to 1a-e and the IR spectra are almost superimposable. 1a-e were identified by X-ray studies as cis -MoCl 4 (thp) 2 , in agreement with previous findings. Careful refinement of the X-ray data of 2a-e by modeling one position as disordered between chlorine (minor component) and oxygen (major component) led to the conclusion that 2a-e consisted of a mixture of cis -MoCl 4 (thp) 2 and mer -MoOCl 3 (thp) 2 , the latter being largely prevalent. The MoCl 5 /tetrahydropyran reaction system provides an opportunity for discussing the possible generation of bond stretch isomers.