Synthesis and X-ray structural studies of new spiro-cyclotriphosphazenes

Synthesis and structural studies (1H,13C,31P NMR and X-ray) of new C-bonded cyclotriphosphazenes with heterocyclic substituents from novel phosphinic acid derivatives

“…The influence of spiro substituents on the C-P-C angles was also reported in an earlier work for hexaphenylcyclotriphosphazene (16) and trispiro(biphenyl)cyclotriphosphazene (17). 10 It was shown that the size of the C-P-C angles is smaller in compound 17 (91.7 ) than in 16 (103.8 ), as is observed for products 6 and 2. It can be seen also that the C-P-C angles in the spiro compound 6 are smaller than in 17 with biphenyl substituents.…”

“…8,9 For example, the reaction of phenyllithium with N 3 P 3 F 6 leads to the creation of no more than five P-C bonds to give N 3 P 3 FPh 5 . 8 Accordingly, we applied another pathway, previously used in our laboratory 10 to form the phosphazenic ring, to the syntheses of hexa(2-thienyl)cyclotriphosphazene ( 2 NJC www.rsc.org/njc hexa(3-thienyl)cyclotriphosphazene (4) and tri(3,3 0 -bithienyl-2,2 0 -ylene)cyclotriphosphazene (6). This route (Scheme 1) involves reaction of the appropriate phosphinic amide with the Appel reagent 11 (a mixture of triphenylphosphine, carbon tetrachloride and triethylamine).…”

“…Finally, the tri(3,3 0 -bithienyl-2,2 0 -ylene)cyclotriphosphazene 6 has been obtained, as for cyclotriphosphazenes 2 and 4, by cyclisation of the phosphinic amide 5 (Scheme 1). 10,11 This new cyclotriphosphazene 6 is the first to possess rigid heterocyclic substituents. The very low yield (5%) may be explained by the strain due to the presence of three phosphole rings in the same structure.…”

“…The molecular structures of compounds 2, 4 and 6 consist of a central six-membered ring of alternating nitrogen and phosphorus atoms with each phosphorus atom bonded to two thiophenic substituents for 2 and 4 and to a bithiophene unit for 6, which has adopted the '' paddlewheel '' conformation common to trispirocyclotriphosphazene compounds, with the cyclotriphosphazene and bithienyl heterocycles in nearly orthogonal planes. 10,22 The molecular structure of 2, 4 and 6 are depicted in Fig. 3.…”

Determination of 31P,31P coupling constants in cyclotriphosphazenes and their influence on 1H and 13C NMR spectra of phosphorus substituents

“…The residue was purified by column chromatography (alumina-n-hexane). 31 P NMR, (18), N 3 P 3 (OPh) 5 (NHCHMePh) (19), N 3 P 3 (OPh) 5 (NHCHPhCO 2 Et) (20), N 3 P 3 (7-azaindol-1-yl) 5 (NHCHPhCO 2 Et) (21) and N 3 P 3 (pyrrol-1-yl) 5 (NHCHMePh) (22) These procedures begin with the syntheses of N 3 P 3 R 5 Cl derivatives which have been described previously: N 3 P 3 (OPh) 5 Cl, 26 N 3 P 3 (pyrrol-1-yl) 5 Cl 18 (10a), N 3 P 3 (7-azaindol-1-yl) 5 Cl 18 (10b).…”