Electronic structure and spectroscopy of the cycloheptatrienyl molybdenum halide complexes [MoBrL2(eta-C7F7)](n+) (L-2=2CO, n=0; L-2=2,2 '-bipyridyl, n=0 or 1)

Research output: Contribution to journalArticle

  • External authors:
  • Kathryn A E Roberts
  • Neil J. Brown
  • Hannah N. Roberts
  • Paul Low
  • Mark Whiteley

Abstract

DFT calculations at the B3LYP/Def2-SVP level have been conducted on the half-sandwich cycloheptatrienyl molybdenum complexes [Mo(CO)(3)(eta-C7H7)(+), [1](+) and [MoBrL2(eta-C7H7)](n+) (L-2= 2 CO, n = 0, 2; L-2= bpy, n = 0, 3; L-2 = bpy, n = 1, [3](+); bpy = 2,2'-bipyridyl). In all cases, strong delta-bonding interactions operate between the e(2) level of the C7F7 ring and metal d(xy), and d(x2-y2) orbitals resulting in a metal-centred HOMO with substantial d(z2), character in the 18-electron, closed shell systems. The experimental electronic UV-Vis spectra of [1](+), 2 and 3 are accurately reproduced by TD-DFT methods, For complexes 2 and 3, assignments made with the assistance of calculated spectra indicate that absorptions in the region 390-770 nm originate from a series of MLCT (metal-ligand charge transfer) or ILCT (inter-ligand charge transfer) transitions in which carbonyl, C7H7 and 2,2'-bipyridyl ligands act as acceptor systems from the metal or mixed metal and bromide donor groups. The metal-centred, one-electron oxidation of 3 to 3[PF6] results in almost complete quenching of the visible region MLCT/ILCT absorptions of 3 and replacement with weak transitions probably arising from bromide to metal LMCT (ligand to metal charge transfer) processes. (C) 2014 Elsevier Ltd. All rights reserved.

Bibliographical metadata

Original languageEnglish
Pages (from-to)89-97
Number of pages8
JournalPolyhedron
Volume86
DOIs
StatePublished - 2015