Crystalline inclusion compounds derived from bulky organosilicon hosts – design, synthesis, structure and stability

Crystal structure of 4,4′-diethynylbiphenyl

“…None of the molecules is planar, with the two benzene rings of each molecule inclined to one another at angles of 42.41 (4), 24.07 (6), 42.59 (4) and 46.88 (4) for molecules 1-4, respectively. Bond distances and angles in the biphenyl ring systems are not unusual and compare well, both internally, over the four unique molecules, and with those observed in related systems (see for example: O'Brien et al, 2010, Butler et al, 2008Muller, et al, 2006, Nitsche et al, 2003. The Cn4-Cn7 and Cn4 0 -Cn7 0 distances (n = 1-4) [mean 1.445 (2) Å ] are generally somewhat long, enough indeed to raise alerts in the checkCIF procedure.…”

“…Zhou et al, 2012;McAdam et al, 2010;O'Brien et al, 2010, Zeng et al, 2007Muller, et al, 2006;Nitsche et al, 2003). Second, the well represented class of organometallic acetyl-818 Tagg et al C 16 H 10 Acta Cryst.…”

Synthesis and X-ray Crystal Structures of New Tetrahedral Arylethynyl Substituted Silanes

“…Previously, we were successful in the synthesis of some arylethynyl substituted silicon-centered [22] or related bulky organosilicon compounds showing the property of crystalline inclusion formation [23]. Here, we report on the crystal structures of four tetrakis(arylethynyl)silanes (1)(2)(3)(4) differing in the substitution of the aryl rings, including also compound 5 which is an analogue of 4 without the ethynylene units (Scheme 1).…”

Controlling Molecular Organization by Using Phenyl Embraces of Multiple Trityl Groups

“…Together, these data suggest that sixfold embraces are not likely to be highly effective motifs for controlling molecular organization unless multiple trityl groups or analogues are incorporated in ways that keep them apart and impede intramolecular interactions. Structures of elegantly designed compounds of this type, in which groups Ph 3 X (X = C, Si, Sn, and Pb) or related substituents are linked to rigid linear ( 1 ), trigonal ( 2 ), or tetrahedral ( 3 ) cores, have been reportedby Garcia-Garibay, Hart, Weber, and others. − Surprisingly, however, only a small minority of the structures analyzed in this set of compounds incorporate any sixfold embraces. The low frequency reveals the capricious nature of trityl groups and analogues as tools for directing molecular organization.…”

“…The low frequency reveals the capricious nature of trityl groups and analogues as tools for directing molecular organization. We attribute this behavior to three primary factors: (1) sixfold embraces are not dramatically stronger than many alternative arrangements of interacting phenyl rings; (2) attaching multiple globular trityl groups and analogues to simple linear or trigonal cores creates awkward molecular topologies that cannot be packed efficiently, and these problems may be exacerbated when sixfold embraces are present; − and (3) the ideal 3̅ axis of classic sixfold embraces must be properly matched with the geometry of the cores to avoid enforced disorder or the formation of structures with low symmetry …”