Photophysical studies of trans-bis(phenylethynyldiisopropylamidinato)bis(acetato)dimetal complexes involving MM quadruple bonds where M = Mo or W

J Phys Chem A. 2010 Dec 9;114(48):12675-81. doi: 10.1021/jp108544v. Epub 2010 Nov 10.

Abstract

The title compounds trans-M(2)(O(2)CMe)(2)[C((i)PrN)(2)C≡C-Ph](2), I (M = Mo) and II (M = W), show electronic absorptions in the visible region of the spectrum assignable to (1)MLCT [M(2)δ to phenylethynylamidinate π*]. These compounds show dual emission from S(1) and T(1) states. For both I and II, S(1) is (1)MLCT, but for I the T(1) state is shown to be MMδδ* while for II T(1) is (3)MLCT. The lifetimes of the S(1) and T(1) states have been determined by femtosecond and nanosecond transient absorption spectroscopy: for I S(1) ∼ 20 ps and T(1) ∼ 100 μs and for II S(1) ∼ 6 ps and T(1) ∼ 5 μs. From solvent dependence of the absorption and emission spectra, we suggest that the S(1) states are localized on one amidinate ligand though the initial absorption is to a delocalized state.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Alkynes / chemistry
  • Amidines / chemistry
  • Models, Molecular
  • Molybdenum / chemistry*
  • Organometallic Compounds / chemistry*
  • Photochemistry
  • Quantum Theory*
  • Tungsten / chemistry*

Substances

  • Alkynes
  • Amidines
  • Organometallic Compounds
  • Molybdenum
  • Tungsten