Lang Sandra M, Bernhardt Thorsten M, Bakker Joost M, Barnett Robert N, Landman Uzi
Institute of Surface Chemistry and Catalysis, University of Ulm, Albert-Einstein-Allee 47, 89069 Ulm, Germany.
Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands.
Phys Chem Chem Phys. 2023 Nov 29;25(46):32166-32172. doi: 10.1039/d3cp04035f.
The interaction of free manganese oxide clusters, MnO ( = 1-9, = 0-12), with formic acid was studied infrared multiple-photon dissociation (IR-MPD) spectroscopy together with calculations using density functional theory (DFT). Clusters containing only one Mn atom, such as MnO and MnO, bind formic acid as an intact molecule in both the - and -configuration. In contrast, all clusters containing two or more manganese atoms deprotonate the acid's hydroxyl group. The coordination of the resulting formate group is strongly cluster-size-dependent according to supporting DFT calculations for selected model systems. For MnO the co-existence of two isomers with the formate bound in a bidentate bridging and chelating configurations, respectively, is found, whereas for MnO the bidentate chelating configuration is preferred. In contrast, the bidentate bridging structure is energetically considerably more favorable for MnO. This binding motif stabilizes the 2D ring structure of the core of the MnO cluster with respect to the 3D cubic geometry of the MnO cluster core.
采用红外多光子解离（IR-MPD）光谱法并结合密度泛函理论（DFT）计算，研究了自由氧化锰簇（MnO，n = 1 - 9，m = 0 - 12）与甲酸的相互作用。仅含一个锰原子的簇，如MnO和MnO，以完整分子形式在α-和β-构型中结合甲酸。相比之下，所有含两个或更多锰原子的簇会使酸的羟基去质子化。根据对选定模型体系的DFT计算，所得甲酸根基团的配位强烈依赖于簇的大小。对于MnO，发现两种异构体共存，甲酸根分别以双齿桥连和螯合构型结合，而对于MnO，双齿螯合构型更受青睐。相反，双齿桥连结构对于MnO在能量上更为有利。相对于MnO簇核的三维立方几何结构，这种结合模式稳定了MnO簇核核心的二维环状结构。
