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Structural Effects of Varied Steric Bulk in 2,(4),6‐Substituted Dimethylthallium(III) Phenoxides
Author(s) -
Briand Glen G.,
Decken Andreas,
McKelvey J. Ian,
Zhou Yukun
Publication year - 2011
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201100043
Subject(s) - chemistry , steric effects , bond length , crystallography , raman spectroscopy , molecular geometry , tetrahydrofuran , nuclear magnetic resonance spectroscopy , ether , stereochemistry , molecule , crystal structure , solvent , organic chemistry , optics , physics
Abstract The structural effects of varied steric bulk on 2,(4),6‐substituted dimethylthallium(III) phenoxides has been examined. The facile reaction of Me 3 Tl with a series of 2,(4),6‐substituted phenols in toluene or diethyl ether resulted in the formation of the species [Me 2 TlO(2,6‐R 2 C 6 H 3 )] 2 [R = H ( 4 ), Me ( 5 ), i Pr ( 6 ), Ph ( 7 )] and [Me 2 TlO(2,4,6‐ t Bu 3 C 6 H 2 )] ( 8 ). All compounds have been characterized by elemental analysis as well as their melting point; FTIR, FT‐Raman, solution 1 H and 13 C{ 1 H} NMR spectroscopy; and X‐ray crystallography. The structures of 4 – 7 are dimeric through short intermolecular Tl–O interactions, which yield a symmetric Tl 2 O 2 unit and a distorted seesaw C 2 O 2 bonding environment for thallium. An increase in the steric bulk in 4 – 6 has little effect on Tl–O bond lengths, whereas the C Me –Tl–C Me bond angle was found to significantly decrease. Further, the phenoxide ligands in 5 and 6 were found to be oriented perpendicular to the Tl 2 O 2 unit to minimize steric interactions. Alternatively, compound 7 shows an increase in Tl–O bond lengths and an increase in the C Me –Tl–C Me bond angle compared to 4 – 6 , and orientation of the phenoxide ligands perpendicular to the Tl 2 O 2 core. The significant steric bulk imposed by the –O(2,4,6‐ t Bu 3 C 6 H 2 ) ligand in 8 precludes dimer formation and allows for isolation of a monomeric species that contains a three‐coordinate T‐shaped C 2 O bonding environment for thallium. DFT calculations show that the energetic favorability of dimer formation decreases with increased phenoxide steric bulk.