N,N'-fused bisphosphole: heteroaromatic molecule with two-coordinate and formally divalent phosphorus. Synthesis, electronic structure, and chemical properties.

The reduction of 6,12-dichloro-1,2,3,4,7,8,9,10-octahydro-6H,12H-[1,2,3]benzodiazaphospholo[2,1-a][1,2,3]benzodiazaphosphole (3) by metallic magnesium in tetrahydrofuran (THF) affords the N,N'-fused bisphosphole 1 in 92% yield. The compound reveals a novel type of 10π-electron heteroaromatic system [NICS(0) = -11.4], containing a two-coordinate and formally divalent phosphorus atom.

The intramolecular rearrangement of phosphinohydrazides [R'2P-NR-NR-M] → [RN═PR'2-NR-M]: general rules and exceptions. transformations of bulky phosphinohydrazines (R-NH-N(PPh2)2, R = tBu, Ph2P).

Reactions of diphosphinohydrazines R-NH-N(PPh(2))(2) (R = tBu (1), Ph(2)P (3)) with some metalation reagents (Co[N(SiMe(3))(2)](2), LiN(SiMe(3))(2), La[N(SiMe(3))(2)](3), nBuLi, MeLi) were performed. Compound 1 was synthesized by the reaction of Ph(2)PCl with tert-butylhydrazine hydrochloride in 83% yield. This compound reveals temperature-dependent (31)P NMR spectra due to hindered rotation about the P-N bonds.

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.