Phenylacetylene: A Hydrogen Bonding Chameleon

Abstract

Molecules with multiple hydrogen bonding sites offer the opportunity to investigate competitive hydrogen bonding. Such an investigation can become quite interesting, particularly when the molecule of interest has neither lone-pair electrons nor strongly acidic/basic groups. Phenylacetylene is one such molecule with three hydrogen bonding sites that cannot be ranked into any known hierarchical pattern. Herein we review the structures of several binary complexes of phenylacetylene investigated using infrared optical double-resonance spectroscopy in combination with high-level ab initio methods. The diversity of intermolecular structures formed by phenylacetylene with various reagents is remarkable. The nature of intermolecular interaction with various reagents is the result of a subtle balance between various configurations and competition between the electrostatic and dispersion energy terms, while trying to maximize the total interaction strength.

Microwave Spectroscopic and Atoms in Molecules Theoretical Investigations on the Ar⋅⋅⋅Propargyl Alcohol Complex: Ar⋅⋅⋅HO, Ar⋅⋅⋅π, and Ar⋅⋅⋅C Interactions

“…Splittings in a-and b-type transitions are of the order of a few kilohertz, whereas splitting in the c-type transitions is relatively larger (0.9-2.6 MHz) and decreases in the order Ar···PA > Ar···PA-D(CD) > Ar···PA-D(OD). [14] Goswami and Arunan reported the microwave spectrum of C 6 H 5 CCH···H 2 O, [15] thereby providing positive confirmation for the structure proposed by Patwari's group. Atoms in molecules (AIM) and electrostatic potential calculations are used to explore the nature of the interactions in this complex.…”

Assessment of intermolecular interactions at three sites of the arylalkyne in phenylacetylene‐containing lithium‐bonded complexes: Ab initio and QTAIM studies

“…In Ref. [17], conversely, only two sites on phenylacetylene were identified as being available to form hydrogen‐bonded complexes, namely the π‐electron density of the benzene ring (site A) and the π‐electron density of the acetylenic C(7)C(8) bond (site B). Site C is not involved in the phenylacetylene‐containing hydrogen‐bonded complexes.…”

“…There are three possible sites that can offer π electrons to form π‐type lithium bonds: site A is the π‐electron region of the phenyl ring, site B is that of the acetylenic CC bond in the XY plane, and site C is that of the acetylenic CC bond in the YZ plane. Patwari and coworkers[17] proposed that phenylacetylene represents a “hydrogen‐bonding chameleon.” In their work, site A and site B were identified as the main π‐electron donor positions when phenylacetylene engages in noncovalent interactions with hydrogen halides; hydrogen‐bonded complexes involving site C were not observed. To the best of our knowledge, there have not hitherto been any experimental studies on phenylacetylene‐containing lithium‐bonded complexes.…”

Binary Complexes of Ammonia with Phenylacetylenes: A Combined Experimental and Computational Approach to Explore Multiple Minima on Intermolecular Potentials

“…Deperturbation analysis using a simple two-state model places the unperturbed CÀH stretching frequency at 3334 cm À1 , [9] while the weighted average model places the unperturbed CÀH stretching frequency at 3332 cm À1 . [3] The 1C-R2PI spectrum of the PHA-NH 3 complex (Figure 1 A) shows many bands which were assigned to the two structural isomers A 1 and A 2 with the help of IDIR and IR-UV hole burning spectroscopic methods. [3] The 1C-R2PI spectrum of the PHA-NH 3 complex (Figure 1 A) shows many bands which were assigned to the two structural isomers A 1 and A 2 with the help of IDIR and IR-UV hole burning spectroscopic methods.…”