In recent years, our laboratory has reported the preparation of a series of acetylide compounds based on the 3d metal–cyclam design (cyclam = 1,4,8,11–tetraazacyclotetradecane, metal = Fe, Co, and Cr) and NiII–TMC (TMC = 1,4,8,11–tetramethyl–1,4,8,11–tetraazacyclotetradecane), and the investigation of their use as precursors for electronic and optoelectronic materials. Presented here is the chemistry of CrIII acetylide compounds based on the HMC ligand (HMC = 5,5,7,12,12,14–hexamethyl–1,4,8,11–tetraazacyclotetradecane). Thus far, two pairs of cis/trans–[Cr(HMC)(C2R)2]Cl (R = Ph, C2H/TMS) compounds have been synthesized from reactions of cis– or trans– [Cr(HMC)Cl2]Cl and Li–C2R and characterized by single X–ray diffraction, UV–Vis spectroscopy, FTIR, fluorimetry and DFT studies. Single crystal X–ray diffraction studies revealed that these compounds adopt a pseudo-octahedral geometry. The acetylide ligands of the trans–[Cr(HMC)(C2R)2]Cl compounds occupy the apical positions, yielding a more planar HMC backbone. In contrast, the acetylide ligands of the cis– [Cr(HMC)(C2R)2]Cl compounds occupy two of the equatorial positions, and two of the nitrogen centers from the HMC ligand occupy the apical positions, resulting in a bent HMC backbone. The electronic spectra of both the cis– and trans–[Cr(HMC)(C4Y)2]Cl ( Y = –H or –TMS) compounds exhibit d–d bands with pronounced vibronic progression associated with C≡C stretches. These compounds also emit from the ligand-field excited states.

Novel Cr(III)-HMC acetylide complexes: Preparation and emission properties

251st National Meeting (2016)

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