Is bond stretch isomerism in mononuclear transition metal complexes a real issue? The misleading case of the MoCl5/tetrahydropyran reaction system.

Distinct batches of orange (1a-e) and green crystals (2a-e) were isolated from the reactions of MoCl5 with tetrahydropyran (thp), respectively at room temperature (in CH2Cl2) and at ca. 80 °C (in ClCH2CH2Cl). 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-MoCl4(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-MoCl4(thp)2 and mer-MoOCl3(thp)2, the latter being largely prevalent.

[Oral manifestations in gastroesophageal reflux disease]. / Manifestazioni orali da reflusso gastroesofageo.

The gastroesophageal reflux (passage of gastric contents into the oesophagus and the mouth) is the main sign/symptom of a very frequent gastroesophageal reflux disease. Thus, acid regurgitation originates from stomach and it is responsible of the onset of typical symptoms and mucosal injury. Also in oral cavity the noxious acid agent is able to injury oral cavity (soft and hard tissues). These effects are described from international literature, even if a greater interest has shown to date only for hard tissue injury.