Functional Group Variation in tert‐Butyldiphenylsilanes (TBDPS): Syntheses, Reactivities, and Effects on the Intermolecular Interaction Pattern in the Molecular Crystalline State

Abstract

We present the preparation of tert-butyldiphenylsilanes differing in one functional group. The molecular structures of the phenyl (3), methoxy (4), and amino derivatives (5) were elucidated by single-crystal X-ray diffraction analysis and their crystal packing investigated by Hirshfeld surface analysis along with 2D fingerprint plots. In the all-C derivative 3, the high symmetry dependence of the crystal packing enables a multitude of directional C(methyl)À H•••C(π) interactions between the tert-butyl and phenyl groups. The methoxy derivative 4 is characterized by considerably short H•••H contacts possibly resulting from pre-orienting C(aryl)À H•••O and C(aryl)À H•••C(π) hydrogen bonds. In the amino derivative 5, the nitrogen atom is not involved in intermolecular interactions, instead dispersive H•••H contacts might become more important for the crystal cohesion. These findings once again underline the pronounced lone electron pair density transfer from the nitrogen atom towards the silicon atom.

Stereochemically Pure Si‐Chiral Aminochlorosilanes

“… [13] Intermolecular N−H⋅⋅⋅ π interactions likely play an important role in the arrangement of the molecules in the crystal packing of ( S C , S Si )‐ 3 , with the shortest H⋅⋅⋅C contact (3.011 Å) found between the NH function and C17 of the phenyl ring of a chiral amine fragment (Figure 2, top). Considerably close edge‐shifted C−H⋅⋅⋅ π contacts [6b,14] were also found in the crystal structure of ( S C , S Si )‐ 3 between H18 and the acceptor atoms C14, C15, and C16, all belonging to a phenylethylamino moiety with distances of 2.812 Å (H18⋅⋅⋅C15), 2.903 Å (H18⋅⋅⋅C16), and 3.031 Å (H18⋅⋅⋅C14) (Figure 2, top). C−H⋅⋅⋅Cl interactions have been extensively discussed in the literature [12,13,15] .…”

Low and High Z′ Polymorphs of Dibenzyldiphenylsilane: A Hydrocarbon-Patterned Molecular Crystalline System

“…In our group, we are in general interested in questions about the interplay of hydrogen bonds, halogen bonds, and dispersion interactions in molecular crystals in order to better understand certain functional patterns with regard to their intermolecular interaction behavior. − In this context, we were caught by the interesting question of whether one specific polymorph can be reproducibly obtained through optimization of the crystallization process, even if the molecular crystal structures are held together exclusively by weak intermolecular interactions.…”

Influence of Amino Functions on the Coordination Ability of Silyl Ethers and Disiloxanes

“…For the silyl ethers, only a slightly pronounced enhancing effect of the Si–N bond on the coordination ability of the Si–OMe function could be identified. The nitrogen lone electron pair is generally better stabilized in NSiOC ligand 1 than in NCOC ligand 2 by hyperconjugative effects, which leads to the known planarization of the amino group in the silicon-based ligand. − This is shown by the higher hyperconjugative loss of the nitrogen lone electron pair of 0.165 in ligand 1 compared to 0.125 in ligand 2 (rows 10 and 13 in Table ). This loss increases to 0.178 upon coordination to lithium in [ 1 · t BuLi], while no changes occur in [ 2 · t BuLi] (hc loss n N = 0.126).…”

“…Since the planar geometry around nitrogen atoms in amino silanes became known, structural parameters such as Si–N bond lengths and nitrogen coordination geometry have been investigated intensively . Many theoretical and experimental studies on the nature of the silicon–nitrogen bond have been carried out, although the role of hyperconjugative interactions in the silicon–nitrogen bond has also given rise to controversial discussions …”