Cucurbit[n]urils (CB[n]s) are cyclic macrocycles with rich host‐guest chemistry. In many cases, guest binding in CB[n]s results in host structural deformations. Unfortunately, measuring such deformations remains a major challenge, with only a handful of manual estimations reported in the literature. To address this challenge, we have developed the public program ElliptiCB[n], which is available on GitHub, that provides a robust and automated method for measuring the elliptical deformations in CB[n] hosts. We outline the development and validation of this approach, apply ElliptiCB[n] to measure the ellipticity of the 1113 available CB[n] structures from the Cambridge Structural Database (CSD), and directly investigate the structural deformations of CB[5], CB[6], CB[7], CB[8], and CB[10] hosts. We also report the general landscape of accessible CB[n] elliptical deformations and compare ellipticity distributions across CB[n] hosts and host‐guest complexes. We found that in almost all cases guest binding significantly impacts the distribution of host ellipticity distributions and that these distributions are dissimilar across host‐guest complexes of differently sized CB[n]s. We anticipate that this work will provide a useful approach for understanding of the flexibility of CB[n] hosts and will also enable future measurement and standardization of ellipticity measurements of CB[n]s.
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The [ Ph B( t BuIm) 3 ] 1− ligand has gained increased attention since it was first reported in 2006 due to its ability to stabilize highly reactive first row transition metal complexes. In this work, we investigate the coordination chemistry of this ligand with redox-inert zinc to understand how a zinc metal center behaves in such a strong coordinating environment. The Ph B( t BuIm) 3 ZnCl (1) complex can be formed via deprotonation of [ Ph B( t BuIm) 3 ][OTf] 2 followed by the addition of ZnCl 2 . Salt metathesis reaction with nucleophilic n -BuLi yields the highly carbon-rich zinc coordination complex Ph B( t BuIm) 3 ZnBu (2) with three carbene atom donors and one carbanion donor. In contrast, reaction of complex 1 with a less nucleophilic polysulfide reagent, [K.18-C-6] 2 [S 4 ], leads to the formation of a tetrahedral zinc tetrasulfido complex via protonation of one carbene donor to form Ph B( t BuIm) 2 ( t BuImH)Zn(κ 2 -S 4 ) (3).more » « less