Hydroxy- and boronic-acid-functionalized carbosilanes: Synthesis and solid state structure of Si(C6H4-4-SiMe2((CH2)3OH))4

Consecutive synthesis methodologies for the preparation of carbosilanes (Ph)(Me)Si((CH2)3B(OH)2)2 (2), Si(C6H4-4-SiMe2((CH2)3B(OH)2))4 (5), (Ph)(Me)Si((CH2)3OH)2 (3), and Si(C6H4-4-SiMe3−n((CH2)3OH)n)4 (6a, n = 1; 6b, n = 2; 6c, n = 3) are reported. Boronic acids 2 and 5 are accessible by treatment of (Ph)(Me)Si(CH2CHCH2)2 (1) or Si(C6H4-4-SiMe2(CH2CHCH2))4 (4a) with HBBr2·SMe2 followed by addition of water, while 3 and 6 are available by the hydroboration of 1 or Si(C6H4-4-SiMe3−n(CH2CHCH2)n)4 (4a, n = 1; 4b, n = 2; 4c, n = 3) with H3B·SMe2 and subsequent oxidation with H2O2.The single molecular structure of 6a in the solid state is reported. Representative is that 6a crystallized in the chiral non-centrosymmetric space group P212121 forming 2D layers due to intermolecular hydrogen bond formation of the HO functionalities along the crystallographic a and c axes.

Graphical abstractThe synthesis of a series of carbosilanes of type (Ph)(Me)Si((CH2)3X)2 (X = B(OH)2, OH) and Si(C6H4-4-SiMe3−n((CH2)3(X)n))4 (X = OH: n = 1, 2, 3; X = B(OH)2: n = 1) is discussed. The structure of Si(C6H4-4-SiMe2((CH2)3OH))4 in the solid state is reported. Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Hydroboration-hydrolysis/-oxidation leads to HO-/(HO)2B-functionalized carbosilanes. ► Crystallization of non-chiral carbosilane in chiral non-centrosymmetric space group. ► 2-D Layers are formed by molecular recognition. ► Molecular tectons are used in the design of molecular networks in the solid state.