Hydrotris(1-pyrazolyl)borates of chromium(III)

Chromium(III) complexes with terdentate 2,6-bis(azolylmethyl)pyridine ligands: Synthesis, structures and ethylene polymerization behavior

“…Elemental analysis, FTIR, and mass spectroscopy were used to characterize the isolated complexes. The solid state FTIR spectra in KBr pellets show strong absorption bands in the 1519-1523 and 294-360 cm À1 ranges, assigned to m(C-N) and m(Cr-Cl), respectively [21,22]. The spin state of the complexes was confirmed by magnetic susceptibility measurements (l eff.…”

Luminescence and Light‐Driven Energy and Electron Transfer from an Exceptionally Long‐Lived Excited State of a Non‐Innocent Chromium(III) Complex

“…Due to Laporte's rule, the calculated oscillator strengths are very small (1.4–1.5×10 −8 each; Figure S7). The analogous absorption band of the comparable centrosymmetric bis(hydrotris(1‐pyrazolyl)borate)chromium(III) complex [Cr(HBpz 3 ) 2 ] 3+ is of similar intensity (456 nm; ϵ =35 m −1 cm −1 ), while that of [Cr(ddpd) 2 ] 3+ at 435 nm is more intense by two orders of magnitude due to the lack of the inversion center in [Cr(ddpd) 2 ] 3+ . The “octahedral” ligand field splitting Δ o =23 200 cm −1 of [Cr(tpe) 2 ] 3+ (corresponding to the center of the quartet absorption band) is in the same range as that of bpy and ddpd chromium(III) complexes, yet larger than that of [Cr(tpy) 2 ] 3+ due to the unfavorable metal‐ligand orbital overlap of the latter.…”

Luminescence and Light‐Driven Energy and Electron Transfer from an Exceptionally Long‐Lived Excited State of a Non‐Innocent Chromium(III) Complex

“…In the following discussions,the symmetry labels of the D 3d point group are employed for [Cr(tpe) 2 ] 3+ .D ue to Laportesr ule,t he calculated oscillator strengths are very small (1.4-1.5 10 À8 each;F igure S7). The analogous absorption band of the comparable centrosymmetric bis(hydrotris(1-pyrazolyl)borate)chromium(III) complex [Cr(HBpz 3 ) 2 ] 3+ is of similar intensity (456 nm; e = 35 m À1 cm À1 ), [74] while that of [Cr(ddpd) 2 ] 3+ at 435 nm is more intense by two orders of magnitude due to the lack of the inversion center in [Cr(ddpd) 2 ] 3+ . [3] The" octahedral" ligand field splitting D o = 23 200 cm À1 of [Cr(tpe) 2 ] 3+ (corresponding to the center of the quartet absorption band) is in the same range as that of bpy and ddpd chromium(III) complexes,y et larger than that of [Cr(tpy) 2 ] 3+ due to the unfavorable metalligand orbital overlap of the latter.…”