Chemistry of the Phosphorus−Nitrogen Ligands. Multiple Isomeric Transformations of the Diphosphinohydrazine Bearing 8-Quinolyl Substituent: P→C, P→N, and P→P Migrations Caused by Different Factors

The reaction of 8-quinolylhydrazine with 2 equiv of Ph2PCl in the presence of Et3N gives 8-[(Ph2P)2NNH]-Quin (1) (Quin = quinolyl) in 84% yield. The heating of 1 at 130 °C for 1 h in toluene results in migration of the [Ph2PNPPh2] group to a carbon atom of the quinolyl fragment to form an isomer, 7-(Ph2P−NPPh2)-8-NH2-Quin (2). The same migration is caused by the addition of LiN(SiMe3)2 to 1. On the contrary, lithiation of 1 with n-BuLi followed by the addition of ZnI2 (1:1) affords the aminoquinolyl−phosphazenide dinuclear complex [ZnI(8-Quin-NPPh2N-PPh2)-κ3N,N,P]2 (4), which is a result of P→N migration. Compound 1 itself reacts with ZnI2 in THF to form 4 and protonated molecule 1·HI, which rearranges to the more stable iminobiphosphine salt (Ph2P-PPh2N-NH-Quin-8)·HI. Zinc iodide reacts with 2 equiv of the lithium salt of 1 without rearrangement, to form homoleptic aminoquinolyl zinc complex Zn[{(Ph2P)2NN-Quin-8}-κ2N,N]2 (6). Solutions of 4 and 2 in dichloromethane show luminescence at 510 and 460 nm (quantum yields are 45% and 7%, respectively). DFT calculations were provided for possible isomers and their complexes.