Phosphorus-nitrogen compounds (Part 51): the relationship between spectroscopic and crystallographic data of mono- and di-spirocyclophosphazene derivatives with 4-fluoro/nitrophenylmethyl pendant arm/arms

Abstract

A great wealth of structural information about phosphazenes can be gleaned from the combined spectroscopicand crystallographic data. When data from ${}^{31}P$ NMR spectroscopy and X-ray crystallography are put togetherlike pieces in a puzzle, a number of correlations can be obtained for phosphazene derivatives. A systematic studyconcerning the correlations among the structural parameters (e.g., ${}^{31}P$ NMR data, endocyclic/exocyclic NPN bondangles and bond lengths) revealed some characteristics of mono- and di-spirocyclophosphazene derivatives bearing 4-fluoro/nitrophenylmethyl pendant arm/arms. These correlations include the relationship between the δPspiro shifts,the values of electron density transfer parameters ∆(P–N), and the endocyclic and exocyclic NPN bond angles ofthe cyclophosphazenes. The structural parameters were compared with each other for 19 compounds of 5 differentarchitectural types of cyclophosphazenes with 5- to 7-membered spiro-rings.