Über die Nichtexistenz eines einfachen μ-oxo-Diphosphorans mit zwei 1.3.5.7-Tetramethyl-1.3.5.7-tetra-aza-4λ5-phosphaspiro[3.3]heptan- 2.6-dion-Gruppierungen: Darstellung und Struktur eines zweifach mit N,Nʹ-Dimethylharnstoff überbrückten λ5P–O–λ5P-Diphosphorans/On the Nonexistence of a Simple μ-Oxo-diphosphorane Involving two 1,3.5.7-Tetramethyl-1.3.5.7-tetra-aza-4λ5-phospha-spiro[3.3]heptane-2.6-dione Groupings: Preparation and Structure of a λ5P–O–λ5P Diphosphorane Doubly Bridged with N.Nʹ-Dimethylurea

The reaction between the spiro-chlorophosphorane, [O = C (NMe)2]2PX (X = Cl), and the related trimethylsiloxy compound (X = OSiMe3) was expected to give rise to the formation of a μ-oxo-bis(spirophosphorane), [[O = C(NMe)2]2P]2O. Instead, an isomer of the expected compound, with two N.Nʹ-dimethylurea bridges across a λ5P-O-λ5P bond system was obtained. The identity of the product was established by spectroscopic means (IR , NMR, mass spectroscopy), and by a single crystal X-ray diffraction study.