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 Ph(2)PCl in the presence of Et(3)N gives 8-[(Ph(2)P)(2)NNH]-Quin (1) (Quin = quinolyl) in 84% yield. The heating of 1 at 130 °C for 1 h in toluene results in migration of the [Ph(2)PNPPh(2)] group to a carbon atom of the quinolyl fragment to form an isomer, 7-(Ph(2)P-N═PPh(2))-8-NH(2)-Quin (2). The same migration is caused by the addition of LiN(SiMe(3))(2) to 1. On the contrary, lithiation of 1 with n-BuLi followed by the addition of ZnI(2) (1:1) affords the aminoquinolyl-phosphazenide dinuclear complex [ZnI(8-Quin-NPPh(2)═N-PPh(2))-κ(3)N,N,P](2) (4), which is a result of P→N migration. Compound 1 itself reacts with ZnI(2) in THF to form 4 and protonated molecule 1·HI, which rearranges to the more stable iminobiphosphine salt (Ph(2)P-PPh(2)═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[{(Ph(2)P)(2)NN-Quin-8}-κ(2)N,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.