Morlok MM, Docrat A, Janak KE, Tanski JM, Parkin G. The molecular structure of the tris(2-mercapto-1-tolylimidazolyl)hydroborato zinc(2-mercapto-1-tolylimidazole) complex, {[Tmp-Tol]Zn(mimp-Tol)}[ClO4]: intermolecular N–H⋯OClO3versus intramolecular N–H⋯S hydrogen bonding interactions of the mercaptoimidazole ligand.
Dalton Trans 2004:3448-52. [PMID:
15510261 DOI:
10.1039/b412147c]
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Abstract
The molecular structure of the tris(2-mercapto-1-tolylimidazolyl)hydroborato complex [[Tm(p-Tol)]Zn(mim(p-Tol))][ClO(4)].3MeCN has been determined by X-ray diffraction, thereby demonstrating that the mim(p-Tol) ligand exhibits a N-H...O hydrogen bond with the [ClO(4)](-) counterion, [[Tm(p-Tol)]Zn(mim(p-Tol))...(OClO(3))], rather than hydrogen bond with a sulfur of the [Tm(p-Tol)] ligand. DFT calculations on a series of related complexes, namely [[Tm(Me)]Zn(mim(Me))](+), [[Tm(Me)]Zn(mim(Me))]...(OClO(3))], [[Tm(Me)]Zn(mim(Me))]...[O(H)Me]](+), and [[Tm(Me)]Zn(mim(Me))]...(NCMe)](+) demonstrate that an intramolecular N-H...S hydrogen bond within [[Tm(Me)]Zn(mim(Me))](+) is also less favored than the corresponding hydrogen bonding interactions with MeCN, MeOH, and [ClO(4)](-). The inability of the sulfur atoms of [Tm(R)] ligand to act as an effective hydrogen bond acceptor is in marked contrast to the ability of sulfur atoms in thiolate ligands to participate in the formation of N-H...S hydrogen bonds, an observation that reflects the "thione"versus"thiolate" nature of the [Tm(R)] ligand.
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