Understanding the Formation of New Clusters of Alkali and Alkaline Earth Metals:  A New Synthetic Approach, Single-Crystal Structures, and Theoretical Calculations

Abstract

A new synthetic approach, reacting alkaline earth metal iodides with butyllithium, lithium hydroxide, and/or lithium butoxide under salt elimination, is presented, giving access to some interesting clusters of calcium, strontium, and barium, partially in combination with lithium. The so far largest calcium cluster Li[[Ca(7)(mu(3)-OH)(8)I(6)(thf)(12)](2)(mu(2)-I)].3THF, 4, and the new strontium compound [Sr(3)I(3)(OH)(2)(thf)(9)]I, 5, are shown to feature common building blocks of OH-capped M(3) triangles. On the basis of mainly electrostatic interactions, these clusters are not volatile. By introducing LiO(t)Bu, the two clusters [IM(O(t)Bu)(4)[Li(thf)](4)(OH)] (6, M = Sr; 7, M = Ba) are prepared, 7 exhibiting volatility as an important physical property, which makes it a potential precursor for chemical vapor deposition. The structural relationship between 4, 5, 6, and 7 and their respective starting materials is shown, and possible reaction mechanisms are proposed. Exhibiting surprising and new structural motifs, the bonding modes of these clusters are investigated by the electron localization function as well as by ab initio calculations.

Recent advances in tailoring the aggregation of heavier alkaline earth metal halides, alkoxides and aryloxides from non-aqueous solvents

“…The one-dimensional compound 5 can therefore be understood as an excerpt of such a structure. Furthermore, the literature known complex [{Ba(OTf) 2 } 4 (py) 14 transition metals and lanthanides, in which very different bond lengths are observed to proceed similarly. This is of interest as such low-dimensional compounds possess an intrinsic anisotropy, which can be fundamental for the expression of their physical properties.…”

Coordination polymer networks with s-block metal ions

“…This has been exemplified in the studies on alkaline earth metal iodides, which are still quite soluble in organic solvents which may act also as coordinating ligands. In these cases, it is important to control the quantity of water present, as water is a solvent able to dissociate the mainly ionic bonds in alkaline earth metal salts [49][50][51][52][53][54].…”

From Alkaline Earth Ion Aggregates via Transition Metal Coordination Polymer Networks towards Heterometallic Single Source Precursors for Oxidic Materials

“…Unfortunately, they often turned out to form mainly carbonates at low decomposition temperatures, while some of the cluster compounds ( Fig. 1, right) were shown to be successful candidates as starting compounds for the sol-gel as well as MO-CVD method to yield alkaline earth oxides, [18] and are still studied in our group.…”

“…This has first led us to the field of alkali [9][10][11][12] and alkaline earth metal compounds, [13,14] of which a number of new clusters were observed. [15][16][17][18][19][20][21][22][23] Being hard metal ions, mainly O-donor ligands were chosen for the coordination to these group 1 and 2 ions. Among these ligands are charged monodentate ligands OR, R = H, alkyl, aryl, [22,23] as well as the neutral polyether ligands such as oligo dimethyl ethers, [24][25][26][27][28][29][30][31][32] crown ethers [33,34] or calixarene ligands.…”