Synthesis and Characterization of Bridging-Diazene Diiron Half-Sandwich Complexes: The Role of Sulfur Hydrogen Bonding

• Published in: Inorganic chemistry 2024-07, Vol.63 (30), p.14040-14049
• Main Authors: Zhang, Xin, Jiang, Xuebin, Zhao, Qiuting, Li, Yongxian, Feng, Lei, Ye, Shengfa, Tung, Chen-Ho, Wang, Wenguang
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X; 1520-510X
• DOI: 10.1021/acs.inorgchem.4c01783

We report two bridging-diazene diiron complexes [Cp*Fe­(8-quinolinethiolate)]2(μ-N2H2) (1-N2H2 ) and [Cp*Fe­(1,2-Cy2PC6H4S)]2(μ-N2H2) (2-N2H2 ), synthesized by the reaction of hydrazine with the corresponding thiolate-based iron half-sandwich complex, [Cp*Fe­(8-quinolinethiolate)]2 (1) and Cp*Fe­(1,2-Cy2PC6H4S) (2). Crystallographic analysis reveals that the thiolate sites in 1-N2H2 and 2-N2H2 can engage in N–H···S hydrogen bonding with the diazene protons. 1-N2H2 is thermally stable in both solid and solution states, allowing for one-electron oxidation to afford a cationic diazene radical complex [1-N2H2 ]+ at room temperature. In contrast, 2-N2H2 tends to undergo N2H2/N2 transformation, leading to the formation of a Fe­(III)-H species by the loss of N2. In addition to stabilizing HN=NH species through the hydrogen bonding, the thiolate-based ligands also seem to facilitate proton-coupled electron transfer, thereby promoting N–H cleavage.