Yue Mengwei, To Wai-Pong, Zhao Yifan, Hu Qiushi, Chang Xiaoyong, Chen Xihan, Zhang Xi-Ai, Chen Xuebo, Wu Liangliang, Lu Wei
Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, P.R. China.
Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, P.R. China.
Angew Chem Int Ed Engl. 2025 Aug 21:e202509601. doi: 10.1002/anie.202509601.
Two paramagnetic Cr(I) complexes with homoleptic fac-bis(triarylisocyanide) ligands were prepared by chemical oxidation of the Cr(0) precursors and emission spectra with peak maximum at respective 568 and 525 nm have been recorded with THF solutions of these two low-spin d metal complexes at 298 K. Structural, spectroscopic, and theoretical studies revealed that the emission of the Cr(I) complexes could be tentatively assigned to be spin-allowed MLCT excited states. Femtosecond-resolved transient absorption spectra confirmed that the lifetimes of the excited states were in the tens of picoseconds, which could be explained by the fast nonradiative decay of MLCT state through low-lying quartet metal-centered (MC) states. The Cr(I) complexes with luminescent MLCT excited states were distinct from the previously reported d Fe(III) complexes with luminescent LMCT excited states, enriching the diversity of emissive excited states of earth-abundant 3d transition metal complexes.
通过对Cr(0)前体进行化学氧化制备了两种具有均配面式双（三芳基异腈）配体的顺磁性Cr(I)配合物，并在298 K下用这两种低自旋d金属配合物的四氢呋喃溶液记录了最大发射峰分别位于568和525 nm的发射光谱。结构、光谱和理论研究表明，Cr(I)配合物的发射可初步归属于自旋允许的MLCT激发态。飞秒分辨瞬态吸收光谱证实，激发态的寿命在几十皮秒，这可以通过MLCT态通过低位四重态金属中心（MC）态的快速非辐射衰变来解释。具有发光MLCT激发态的Cr(I)配合物与先前报道的具有发光LMCT激发态的d Fe(III)配合物不同，丰富了地壳丰富的3d过渡金属配合物发射激发态的多样性。
