Cyclometallated derivatives of palladium(II) with 1,4-benzodiazepin-2-ones. Crystal structure of (L-H)Pd(PPh3)ClCHCl3 (L = Prazepam: 7-chloro-1-cyclopropylmethyl-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepin-2-one). Synthesis of isoindolobenzodiazepine derivatives by ...

Article abstract of DOI:10.1016/0022-328X(91)86234-H

The dimeric cyclometallated derivatives of palladium(II) <(L-H)PdCl>2, 3 (L = 1, Diazepam: 7-chloro-1,3-dihydro-1-methyl-5-phenyl-2H-1,4-benzodiazepin-2-one) and 4 (L = 2, Prazepam: 7-chloro-1-cyclopropylmethyl-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepin-2-one) react with triphenylphosphine to give the complexes (L-H)Pd(PPh3)Cl, 5 (L = Diazepam) and 6 (L = Prazepam).The crystal structure of 6 was determined by X-ray crystallography.The palladium atom is in a square planar arrangement.The deprotonated ligand is bound to the metal through the 4-nitrogen and the ortho-carbon atom of the 5-phenyl substituent.The phosphorous and the chlorine atoms are trans to the nitrogen and the carbon atoms, respectively: Pd-N = 2.085(2), Pd-P = 2.263(1), Pd-Cl = 2.377(1), Pd-C = 2.009(3) Angstroem.The reaction of the dimeric derivatives <(L-H)PdCl>2 with carbon monoxide was investigated.Under mild conditions (1 atm of CO, room temperature) the unstable (L-H)Pd(CO)Cl derivatives, 7 (L = Diazepam) and 8 (L = Prazepam) are formed, but at high pressure and temperature (60-100 atm of CO, 45-50 deg C), extrusion of palladium occurs and tetracyclic derivatives having an isoindolo ring condensed on the 1,4-benzodiazepin-2-one system, 9-12, are obtained.