Abstract

The adducts trans-L₂PdCl₂ (1, L = Diazepam = 7- chloro-1,3-dihydro-1-methyl-5-phenyl-2H-1,4-benzodiazepin -2-one; 5, L = Prazepam = 7-chloro-1-(cyclopropylmethyl)- 1,3-dihydro-5-phenyl-2H-1,4-benzodiazepin-2-one) were prepared by reaction of PdCl₂ or (PhCN)₂PdCl₂ with Diazepam and Prazepam, respectively.
In the adducts, the benzodiazepines act as monodentate ligands through the 4-nitrogen atom, as shown by the structure of compound 5, determined by X-ray diffraction.
Two crystalline modifications have been characterized: 5a, trans-(Prazepam)₂PdCl₂/CHCl₃ 1/1, monoclinic, space group P2₁/n, a = 11.996(4), b = 13.678(5), c = 12.717(3) Å, β = 98.83(2), Z = 2, R = 0.032; 5b, trans-(Prazepam)₂PdCl₂/CH₂Cl₂ 1/1, monoclinic, space group P2₁/c, a = 14.074(3), b = 14.622(7), c = 19.360(10) Å, β = 100.04(3), Z = 4, R = 0.076.
Cyclometallated derivatives [(L---H)PdCl]₂, 2, L = Diazepam and 6, L = Prazepam, involving both C- and N-intramolecular coordination of the deprotonated ligands, have been obtained by reaction with Na₂[PdCl₄] in ethanol solution. In the dimeric species 2 and 6, the halide-bridge is easily split by reaction with Ph₃P or Tl(acac), to give [(L---H)•(Ph₃P)PdCl], (3, 7) and [(L---H)Pd(acac)] (4, 8) respectively.

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