1436861-05-0Relevant articles and documents
Metal-metal quadruple bonds supported by 5-ethynylthiophene-2-carboxylato ligands: Preparation, molecular and electronic structures, photoexcited state dynamics, and application as molecular synthons
Brown-Xu, Samantha E.,Chisholm, Malcolm H.,Durr, Christopher B.,Spilker, Thomas F.
supporting information, p. 8254 - 8259 (2013/07/19)
From the reaction between M2(TiPB)4 and 2 equiv of 5-ethynylthiophene-2-carboxylic acid (H-ThCCH) in toluene, the complexes trans-M2(TiPB)2(ThCCH)2, where M = Mo (I) or W (II) and TiPB = 2,4,6-triisopropyl benzoate, have been isolated and characterized by 1H NMR, IR, MALDI-TOF MS, UV-vis, steady-state emission, transient absorption, and time-resolved infrared (TRIR) spectroscopies and single-crystal X-ray crystallography for I. The molecular structure of I confirms the trans-substitution pattern and the extended conjugation of the ethynylthienyl ligands via interaction with the Mo2δ orbital. The HOMO of both I and II is the M 2δ orbital, and the intense color of the compounds (I is red and II is blue) is due to the M2δ-to-ThCCH 1MLCT transition. The S1 states for I and II are 1MLCT. The T1 state is 3MLCT for II, but 3MoMoδδ* for I. The TRIR spectra of the ν(Ci - C) stretch in the MLCT states are consistent with the delocalization of the electron over both ThCCH ligands. Compound I is shown to be a synthon for the preparation of trans-Mo2(TiPB) 2(ThCCPh)2 (III) and trans-Mo2(T iPB)2(ThCCAuPPh3)2 (IV). Both III and IV have been characterized spectroscopically and by single-crystal X-ray diffraction. The structure of III indicates the extended π-conjugation of the trans-ethynyl-thienyl units extends to the added phenyl rings.
