Rayyat Huseyn IsmayilovSabina Zahid IsmayilovaDilgam Babir TagiyevAjdar Akber MedjidovYasin Isa JafarovWen-Zhen WangChen-Yu YehSu-Ying ChienGene-Hsiang LeeShie-Ming Peng2025-03-192025-03-192025-06https://scholars.lib.ntu.edu.tw/handle/123456789/725862Through a new two-pyrazine-modulated oligo-α-pyridylamino ligand, N2,N2′-(pyridine-2,6-diyl)bis(N6-(pyrazin-2-yl)pyridine-2,6-diamine) (H4N9-2pz) (1), the highest nuclearity linear nonachromium(II) metal string complex [Cr9(µ9-N9-2pz)4Cl2] (2) was successfully synthesized and structurally characterized. According to X-ray crystallographic studies, the complex 2 showed a localized unsymmetrical structure consisting of four quadruple Cr–Cr bonds and one single high-spin Cr(II) at the end of the molecule. The four deprotonated supporting ligands are helically wrapped around the metal score. Temperature-dependent magnetic study revealed a quintet ground state resulting from the isolated, high-spin Cr(II) atom. Electrochemical studies reveal two reversible oxidation waves at E1/2 = +0.54 V and E1/2 = +0.85 V, indicating that the complex exhibits greater stability against oxidation compared to its one-pyrazine-modulated analogue [Cr9(μ9-N9-mpz)4Cl2], which shows a first oxidation peak at +0.38 V. This enhanced stability is attributed to the stronger electron-withdrawing nature of the two-pyrazine-modulated H4N9-2pz ligand. So, in spite of similar crystal structure and magnetic properties, the newly synthesized nonanuclear Cr(II) string is characterized by very different electrochemical properties and short Cr-axial ligand distances compared to its one-pyrazine-modulated analogue [Cr9(μ9-N9-mpz)4Cl2]. Overall, these findings highlight the critical role of the pyrazine-modulated ligand in enhancing the stability and electron structure of nonachromium string complexes, paving the way for designing more stable and oxidation-resistant metal chains.enChain structureChromiumModified N ligandMultiple bondX-ray diffraction[SDGs]SDG3journal article10.1016/j.molstruc.2025.141592