Synthesis, structure and properties of [ReVL(O)Cl3], [ReVL(NR)Cl3], [ReIIIL(OPPh3)Cl3], and [ReIIIL(PPh3)Cl3] [L = 2-(arylazo)-1-methylimidazole, R = aryl]

Indranil Chakraborty, Sibaprasad Bhattacharyya, Sangeeta Banerjee, Bimal Kumar Dirghangi, Animesh Chakravorty

Research output: Contribution to journalArticlepeer-review

Abstract

The reaction of KReO4 with L [2-(arylazo)-1-methylimidazole, with aryl = Ph (L1), C6H4Me-p (L2) or C6H4Cl-p (L3)] in concentrated HCl afforded [ReVL(O)Cl3] 1. Aromatic amines and PPh3 smoothly converted 1 into [ReVL(NR)Cl3] 2 and [ReIIIL(OPPh3)Cl3] 3 respectively. Treatment of 3 with PPh3 yielded [ReIIIL(PPh3)Cl3] 4. Complexes of type 3 and 4 display large paramagnetic shifts of 1H NMR lines which spread over ≈60 ppm. Structure determination of [ReL1(O)Cl3] 1a, [ReL2(NC6H4Me-p)Cl3] 2a, [ReL3(OPPh3)Cl3] 3c and [ReL3(PPh3)Cl3] 4c has revealed meridional geometry for all except 4c which is facial. In the latter Re-azo and Re-PPh3 back bonding is maximized. The metal atom is displaced away from the equatorial plane by ≈0.3 Å towards the oxo ligand in 1a and the imido ligand in 2a. The imidazole nitrogen is co-ordinated trans to oxo, imido, Ph3PO and chloride ligands in 1a, 2a, 3c and 4c, respectively. The azo N=N distance is lengthened by ≥0.05 Å as a result of direct (3c, 4c) or indirect (1a, 2a) Re-azo back bonding. Azo reduction potential values are consistent with the low-lying nature of the azo(π*) orbital. The metal reduction potentials follow the trends: ReVI-ReV, 1 > 2 (imido better donor than oxo); ReIV-ReIII, 4 > 3 (stabilization of t2 by ReIII-PPh3 back bonding).

Original languageEnglish (US)
Pages (from-to)3747-3753
Number of pages7
JournalJournal of the Chemical Society - Dalton Transactions
Issue number21
DOIs
StatePublished - Nov 7 1999
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)

Fingerprint

Dive into the research topics of 'Synthesis, structure and properties of [Re<sup>V</sup>L(O)Cl<sub>3</sub>], [Re<sup>V</sup>L(NR)Cl<sub>3</sub>], [Re<sup>III</sup>L(OPPh<sub>3</sub>)Cl<sub>3</sub>], and [Re<sup>III</sup>L(PPh<sub>3</sub>)Cl<sub>3</sub>] [L = 2-(arylazo)-1-methylimidazole, R = aryl]'. Together they form a unique fingerprint.

Cite this