Bis(2-naphthylmethyl)diphenylsilane

The title compound, C34H28Si, was prepared as an internal standard for diffusion-ordered NMR spectroscopy. The four ligands are arranged tetrahedrally around the Si atom. The two naphthalene systems are nearly perpendicular, making an angle of 86.42 (4)° with one another. A naphthalene system and a phenyl ring are also nearly perpendicular, making an angle of 86.18 (6)° with one another. In the crystal, the molecules pack in columns parallel to the a axis, and exhibit arene C—H⋯π(arene) interactions both within and between columns.

The title compound, C 34 H 28 Si, was prepared as an internal standard for diffusion-ordered NMR spectroscopy. The four ligands are arranged tetrahedrally around the Si atom. The two naphthalene systems are nearly perpendicular, making an angle of 86.42 (4) with one another. A naphthalene system and a phenyl ring are also nearly perpendicular, making an angle of 86.18 (6) with one another. In the crystal, the molecules pack in columns parallel to the a axis, and exhibit arene C-HÁ Á Á(arene) interactions both within and between columns.

S1. Comment
The title compound was prepared as an internal standard for diffusion-ordered NMR spectroscopy. A recent paper on this subject (Li et al., 2009) suggests an internal standard method for correlating diffusion coefficients with formula weights.
The title compound was chosen because its shape both approximates that of a spheroid and is similar to that of the species being studied. In addition, it neither reacts with the species under study nor gives interfering NMR signals.
The ligands are arranged tetrahedrally around the silicon atom. The two naphthalene rings of the title compound are nearly perpendicular, making an angle of 86.42 (4)° with one another. A naphthalene ring and a phenyl ring are also nearly perpendicular, making an angle of 86.18 (6)° with one another. The angle between the phenyl rings is 74.35 (7)°.
The molecules pack in columns parallel to the a axis and exhibit arene C-H··· arene π interactions both within and

S2. Experimental
A dry, 250 ml Schlenk flask, equipped with a magnetic stir bar, was charged with 2-methylnaphthalene (I) (4.26 g, 300 mmol) and potassium tert-butoxide (3.92 g, 350 mmol). The Schlenk flask was purged with nitrogen. Freshly distilled THF (100 ml) was added and the reaction was cooled to -78 °C. n-BuLi (15.2 ml, 2.3 M) was then added dropwise. The Schlenk flask was then capped and kept at -40 °C overnight. The solution was again cooled to -78 °C and 2.09 ml (2.52 g, 100 mmol) of dichlorodiphenylsilane was added dropwise. The reaction mixture was allowed to warm to room temperature and stirred for 2 h. The mixture was then quenched with deionized water and extracted three times with hexanes. The combined organic layers were dried with magnesium sulfate, filtered, and evaporated. Bulb-to-bulb distillation gave a tan solid, which was recrystallized from hexanes to yield colorless crystals of the title compound (II) (2.56 g, 55% recovery).  92, 125.83, 126.27, 126.73, 127.10, 127.36, 127.71, 128.19, 129.59, 130.65, 133.06, 134.18, 135.14, 136.11

S3. Refinement
The four H atoms bonded to the methylene carbons were located in a difference map and refined. All other H atoms were constrained using a riding model; the C-H bond lengths were fixed at 0.93 Å with U iso (H) = 1.2 U eq (C).

Figure 2
Diagram showing how molecules of the title compound form columns parallel to the a axis. Naphthyl-phenyl C-H···π interactions between columns and phenyl-phenyl C-H···π interactions within columns are illustrated   Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.