Arylazoimidazole compounds of rhenium nitrosyl: Synthesis, spectral characterization and reactivity

Unexpected formation of a new nitrosylrhenium(II) complex from oxorhenium(V)

“…The paramagnetism of 1 was established by the Evans' method at 300 MHz, which gave a l eff value of 1.82 BM at 295 K. This value is slightly higher than the spin-only value expected for a single electron in a low-spin d 5 octahedral Re(II) system, and has been ascribed to the negative value of the spin-orbit coupling constant [5].…”

“…The most general method of preparation is the reductive nitrosylation of perrhenate or oxorhenium(V) compounds by gaseous nitric oxide or alkaline hydroxylamine [4,5]. For example, the rhenium(II) complex [Re(NO)Br 3 (PPh 3 ) 2 ] was isolated from the reaction of trans-[ReOBr 3 (PPh 3 ) 2 ] with gaseous nitric oxide in the presence of excess free PPh 3 in benzene [6].…”