UCLA

The synergistic interaction between a metal center and ligand to activate a substrate, known as metal-ligand cooperativity (MLC), has served as an effective strategy for small molecule activation and catalysis, but MLC has seen limited application in the synthesis of inorganic materials, in part, because of an incomplete understanding of molecular parameters required to facilitate such processes. Herein, we demonstrate the synthesis of zero-valent metals and metal selenides facilitated by MLC. Divalent metal aminoxide complexes (metal = Mg, Ca, Sr, Zn, Cd, Sn, and Pb; aminoxide = 2,2,6,6-tetramethylpiperidinyl-1-oxide (TEMPO-)) were systematically synthesized and structurally characterized. Critically, Gutmann-Beckett analysis of the compounds showed that hydrogenolysis reactivity trended with Lewis acidity of the metal center, and gas-phase proton affinity calculations showed no correlation between metal ion identity and nitrogen basicity. When treated with H2, complexes [Cd(TEMPO)2]2·2THF ([Cd]) and [Pb(TEMPO)2]2 ([Pb]) were reduced to elemental Cd0 and Pb0, respectively, as assessed by powder X-ray diffraction. Furthermore, treatment of complexes [Cd] or [Pb] with H2 in the presence of Ph3PSe led to the formation of CdSe and PbSe, respectively, along with Ph3P and 2,2,6,6-tetramethylpiperidin-1-ol (TEMPOH). Our studies suggest that an MLC-mediated hydrogenolysis reactivity pathway can be leveraged to furnish putative transient metal-hydride species, and such species could serve as zero-valent metal synthons for binary material synthesis.