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Synthesis, Characterization, and Reactivity of Cyclometalated Gold(III) Dihalide Complexes in Aqua Regia
Author(s) -
Levchenko Volodymyr A.,
Nova Ainara,
ØienØdegaard Sigurd,
Balcells David,
Tilset Mats
Publication year - 2020
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.202000529
Subject(s) - chemistry , halide , aqua regia , reactivity (psychology) , chelation , medicinal chemistry , metal , bond cleavage , molecule , stereochemistry , crystallography , inorganic chemistry , organic chemistry , catalysis , medicine , alternative medicine , pathology
A range of N,C‐chelated, cyclometalated gold(III) complexes Au( ppy R )X 2 have been prepared and characterized by spectroscopic, crystallographic, and computational means. Here, ppy H is 2‐phenylpyridine dicarboxylic acid (series 1 ), ppy Et is diethyl 2‐phenylpyridine dicarboxylate (series 2 ), and X is trifluoroacetate OAc F ( a ), Cl ( b ), Br ( c ), or I ( d ) anion. The dihalo complexes 1b ‐ d and 2b‐d are obtained when Au( ppy R )(OAc F ) 2 ( 1a and 2a ) are treated with HNO 3 /HX mixtures ( aqua regia X ). Good to high yields are obtained with short reaction times (< 30 min) and simple work‐up. Notably, the strongly acidic medium does not cause protolytic cleavage of the Au–C or Au–N bonds in the chelate, nor is ester hydrolysis of complexes 2b‐d seen. Ethylene inserts into an Au–O bond of 1a and 1b , and the resulting trifluoroacetoxyethyl–Au complexes can be further elaborated in aqua regia without cleavage of the two Au–C bonds in the molecule. Facile, mutual halide exchange reactions between complexes with different halides ( 1b and 1d , 1c and 1d ) were observed and led to formation of mixed‐halide complexes Au( ppy H )(X)(Y). These exchange reactions occurred with complete stereoselectivity. The stereoisomer produced was the one expected based on the relative trans influence of the halides (I > Br > Cl), i.e. the highest trans influence halide was located trans to N which is the lowest trans influence end of the chelate. These thermodynamic preferences were also investigated by DFT computations.