Two modifications of a five-coordinate silicon complex

TBPY-5-34-(Butane-1,4-di­yl)(2-{[1-(2-oxidophen­yl)ethyl­idene-κO]amino-κN}ethano­lato-κO)silicon, C₁₄H₁₉NO₂Si, crystallizes in two modifications. The monoclinic form, (IIm), was obtained by crystallization over a period of 2 d at room temperature; the ortho­rhom­bic form, (IIo), crystallized overnight at 248 K. The main difference between the two mol­ecular structures involves the angles in the equatorial plane of the trigonal bipyramid around silicon. Form (IIm) has an O—Si—O angle of ca 121° and O—Si—C angles of ca 121 and 116°. In form (IIo), the corresponding angles are ∼123, 124 and 111°. There are also significant differences in the packing: (IIm) shows π stacking, whereas (IIo) does not.