2,3J(P,X) [X = H, C] coupling constants dependency on the ring size, hybridization and substituents in new diazaphospholes and diazaphosphorinanes, NMR and X-ray crystallography studies

New diazaphospholes and diazaphosphorinanes (1–12) were synthesized and characterized by 1H, 13C, 31P NMR, mass and IR spectroscopy and elemental analysis. The factors which affect the 2,3J(P,X) (XH, C) coupling constants in compounds 1–12 were considered. The ring size and the hybridization are parameters which change the 2J(PNH) coupling constant in the sequence benzodiazaphospholes > diazaphospholes > diazaphosphorinanes. Also, attention was paid to exocyclic substituent effects. Asymmetric diazaphospholes 5–8 indicate two different 2J(P,C)aliphatic values, and the more deshielded carbon atom has a higher coupling constant. The crystal structures of compounds 7 and 10–12 were determined by X-ray crystallography. Hydrogen bonds produce a 2D framework for compound 10, which is composed of two symmetrically independent molecules. Compounds 7, 11 and 12 exist as a polymeric chain, 2D framework and centrosymmetric dimer, respectively, which are made by hydrogen bonds.

Graphical abstractNew diazaphospholes and diazaphosphorinanes were synthesized and characterized by NMR, IR and mass spectroscopic methods. Effective parameters for 2,3J(P,X) [X = H, C] coupling constants are discussed. The crystal structures of four compounds were determined by X-ray crystallography.Figure optionsDownload full-size imageDownload as PowerPoint slide