Reaction of Ru(PPh3)3Cl2 with 2-(arylazo)pyrimidines.: Spectral and redox characterisation of the products.: Part V.: Single crystal X-ray structure of Ru(PPh3)2(papm)Cl2 (papm=2-(phenylazo)pyrimidine)

Reaction of 2-(arylazo)pyrimidine (aapm) with Ru(PPh3)(3)Cl-2 in CH2Cl2 solution affords [Ru(PPh3)(2)(aapm)Cl-2] (2) while the reaction under refluxing conditions in EtOH isolates [Ru(PPh3)(2)(aapm)(2)](ClO4)(2).H2O (3/4). Single crystal X-ray diffraction study of dichloro-bis(triphenylphosphine){2-(phenylazo)pyrimidine} ruthenium(II) has assigned a cis-Ru(PPh3)(2) motif to the complex. Isomers of [Ru(PPh3)(2)(aapm)](ClO4)(2) have been characterised by H-1 NMR data and they exist in cis-tians-cis and cis-cis-cis configurations in which coordination is considered with reference to three pairs of sequence of P, P (PPh3 abbreviated as P), N, N (N is N(pyrimidine)) and N ', N ' (N ' is N(azo)). The complexes exhibit MLCT transitions in the visible region. Redox studies show the Ru(III)/Ru(II) couple is in the range 0.8-1.2 V vs. SCE and [Ru(PPh3)(2)(aapm)(2)](ClO4)(2) exhibits a higher potential value than that of [Ru(PPh3)(2)(aapm)Cl-2]. (C) 2001 Elsevier Science B.V. All rights reserved.