Intermetallic Competition in the Fragmentation of Trimetallic Au–Zn–Alkali Complexes

Abstract

Cationization is a valuable tool to enable mass spectrometric studies on neutral transition-metal complexes (e.g., homogenous catalysts). However, knowledge of potential impacts on the molecular structure and catalytic reactivity induced by the cationization is indispensable to extract information about the neutral complex. In this study, we cationize a bimetallic complex [AuZnCl3 ] with alkali metal ions (M(+) ) and investigate the charged adducts [AuZnCl3 M](+) by electrospray ionization mass spectrometry (ESI-MS). Infrared multiple photon dissociation (IR-MPD) in combination with density functional theory (DFT) calculations reveal a μ(3) binding motif of all alkali ions to the three chlorido ligands. The cationization induces a reorientation of the organic backbone. Collision-induced dissociation (CID) studies reveal switches of fragmentation channels by the alkali ion and by the CID amplitude. The Li(+) and Na(+) adducts prefer the sole loss of ZnCl2 , whereas the K(+) , Rb(+) , and Cs(+) adducts preferably split off MCl2 ZnCl. Calculated energetics along the fragmentation coordinate profiles allow us to interpret the experimental findings to a level of subtle details. The Zn(2+) cation wins the competition for the nitrogen coordination sites against K(+) , Rb(+) , and Cs(+) , but it loses against Li(+) and Na(+) in a remarkable deviation from a naive hard and soft acids and bases (HSAB) concept. The computations indicate expulsion of MCl2 ZnCl rather than of MCl and ZnCl2 .

Magnetostructural correlation in isolated trinuclear iron(iii) oxo acetate complexes

“…64,65 In such cases it would be more appropriate to compare the relative energies of transition state structures to E 50 com values rather than simple binding energies. 41,49,66 However, in the presented case we investigate a direct bond cleavage void of any involved structural reorganizations. Such cases are known to lack any activation barrier beyond plain endothermicity of the mere bond breaking, 67,68 Pyridine torsional ambiguity.…”

“…38 Experimental results and dedicated ab initio calculations have been combined in order to obtain further insight into the structure and intrinsic properties of likely binding motifs. [39][40][41][42] We have previously investigated [Fe 3 O(OAc) 6 (N 2 ) n ] + complexes (n = 1, 2, 3) by IR-PD and observed a slight distortion of the triangular Fe 3 O core geometry by stepwise N 2 coordination to the Fe centers. 43 For this study we exchange the weak binding N 2 ligand with a strong binding pyridine (Py) ligand.…”

Advancing Inorganic Coordination Chemistry by Spectroscopy of Isolated Molecules: Methods and Applications

“…This can become even more of a problem when the strict requirement of CID measurements, i. e. single collision conditions at well‐defined collision energies is no longer fulfilled, for example when conducting measurements within RF ion traps. In such cases it is nevertheless gratifying to realize, that relative values of recorded fragmentation thresholds can still be useful for the interpretation of relative stabilities, for example of Au−Zn−Alkali Complexes, [40] or in magnetostructural correlations within Fe 3 O(ac) 6 + and its complexes with n‐heterocylces. [41] Likewise, the elucidation of roll‐over cyclometallation within Ru II complexes, [42] and further related studies have benefitted from such CID studies and their corresponding interpretation.…”