Investigation of Inter-Ion Interactions inN,N,N',N'-Tetramethylethylenediammonium Dithiocyanate via Experimental and Theoretical Charge Density Studies

Abstract

The crystal structure of the N,N,N',N'-tetramethylethylenediammonium dithiocyanate salt has been examined by experimental charge density studies from high-resolution X-ray diffraction data. The corresponding results are compared with multipole refinements, using theoretical structure factors obtained from a periodic density functional theory calculation at the B3LYP level with a 6-31G(**) basis set. The salt crystallizes in space group P and contains only a single ion pair with an inversion center in the cation. The salt has thus one unique classical N+-H...(NCS)(-) hydrogen bond but also has six other weaker interactions: four C-H...S, one C-H...N, and one C-H...C(pi). The nature of all these interactions has been examined topologically using Bader's quantum theory of "atoms in molecules" and all eight of the Koch-Popelier criteria. The experimental and theoretical approaches agree well and both show that the inter-ion interactions, even in this simplest of systems, play an integrated and complex role in the packing of the ions in the crystal. Electrostatic potential maps are derived from experimental charge densities. This is the first time such a system has been examined in detail by these methods.

Systematic experimental charge density analysis of anion receptor complexes

“…The positions and interactions of the TMA cation relative to the receptor in 4, 5 and 6 vary across the series (constant para receptor with different anion), particularly that of the TMA cation in the fluoride structure 6, however the range of the r(r BCP ) and r 2 r(r BCP ) values at the C-N BCPs are consistent with those reported by Munshi et al in the related tetramethylalkyldiammonium salt. 76 In 6 the multipole populations for TMA were taken from the Invariom database enabling the modelling of the electron density of this region, however the similarity of the properties of the r(r BCP ) at the BCPs in 6 with those across the series of structures in this paper and with the literature suggest that this is an acceptable model for the group. As expected with no alteration in the cation between structures 4 ( para chloride complex) and 7 (meta chloride complex), and a similar position and interaction environment in both, the properties of the BCPs between the TMA nitrogen atom and methyl carbons, N(5)-C(14/15/16/17) do not vary significantly in 4 and 7.…”

Exploring the rare S—H...S hydrogen bond using charge density analysis in isomers of mercaptobenzoic acid

“…Indeed, the current version of the CSD (Version 5.37, November 2015) has only 60 crystal structures which possess S-HÁ Á ÁS hydrogen bonds out of 160 organic molecules having S-H bonds. Experimental charge density studies predominately show that sulfur acts as a hydrogen bond acceptor (Munshi & Row, 2002, 2005aMunshi et al, 2006Munshi et al, , 2007. In this article, we report the first experimental charge density study on a S atom acting as a hydrogen-bond donor.…”

Probing of ferrocenylanilines on model micelle/reverse micelle membrane and their enhanced reactivity for reactive oxidants

“…In this case the water is trapped by hydrogen bonding. If the ammonium ion had been formed, the electronic charge density on nitrogen would be changed and behave differently in XRD . Another possibility in this case is the ammonium salt would form with bromide counter ion not with hydroxide on the bases of statistical availability.…”