Strontium silicide

Slightly more reduced but smaller in Mg content is a new ternary strontium silicide with the composition Sr,Mg2Si,o [31] and a mean formal charge of q = -2.6 on silicon. There are two isolated Si anions per formula unit while the other eight silicon atoms form a unit of a linear chain Sij , which is again completely planar. The structure is displayed in Fig. 5b. 

The two-stage reaction of SiO with Mg was not observed in the reduction with other elemental metals, although the final products were mostly analogous. The alkali metals Li, Na, K, and Rb did react with SiO, although the products (possibly silicides) could not be identified with certainty due to their extreme sensitivity. In the reaction mixtures of solid SiO with strontium or titanium, SrSi, SrSi2 and TisSia were identified by XRD. Reaction with aluminum did not result in the formation of a silicide but of elemental silicon instead. It should be noted that elemental silicon forms silicides with Mg, Ca, Sr, Ti and the alkali metals, for example, but not with Al. 

For the preparation of strontium and barium silicides, see Wohler and Schuff. The reactionproceeds as in the case of calcium silicide, through at a somewhat higher temperature. 

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