Understanding the formation of new clusters of alkali and alkaline Earth metals: a new synthetic approach, single-crystal structures, and theoretical calculations.

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[{Ca7(μ3-OH)8I6(thf)12}2(μ2-I)]·3THF, 4, and the new strontium compound [Sr3I3(OH)2(thf)9]I, 5, are shown to feature common building blocks of OH-capped M3 triangles. On the basis of mainly electrostatic interactions, these clusters are not volatile. By introducing LiOtBu, the two clusters [IM(OtBu)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 the...