X-Ray crystallographic study of a 1,3,2-dioxaphosphorinane dimer containing five-coordinated phosphorus in the 12-membered ring

✍ Scribed by Yande Huang; Alan E. Sopchik; Atta M. Arif; Wesley G. Bentrude

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 677 KB
• Volume: 4
• Category: Article
• ISSN: 1042-7163
• DOI: 10.1002/hc.520040223

✦ Synopsis

Attempted preparation of phosphorane 9 with a 1,3,2dioxaphosphorinane ring attached diequatorially to phosphorus led to a mixture of products from which was isolated 12-membered ring phosphorane 10, formally the dimer of 9, in low yield (22%). An X-ray crystal structure of 10 revealed a highly symmetrical molecule with trigonal bipyramidal geometry at both phosphorus atoms. The 12-membered ring is attached to phosphorus diequatorially. The ring is strongly puckered about phosphorus with an equatorial 0-P-0 angle of 110". The chemical shift equivalence of the CHzO resonances in the ' H NMR spectrum of 10 shows the 12-membered ring to be highly mobile at ambieni probe temperature. At -89'C, these resonances are fully decoalesced. The value of AGS for the process that averages these peaks was found to be 10.1 kcal/mol at coalescence (-42.O"C).