Huang, Deguang Zhang, Xiaofeng J. L. McInnes, Eric McMaster, Jonathan Blake, Alexander J. Davies, E. Stephen Wolowska, Joanna Wilson, Claire Schröder, Martin Crystallographic, Electrochemical, and Electronic Structure Studies of the Mononuclear Complexes of Au(I)/(II)/(III) with [9]aneS<sub>2</sub>O ([9]aneS<sub>2</sub>O = 1-oxa-4,7-dithiacyclononane) The mononuclear macrocyclic complexes [Au<sup>I</sup>([9]aneS<sub>2</sub>O)<sub>2</sub>]BF<sub>4</sub>·MeCN <b>1a</b>, [Au<sup>II</sup>([9]aneS<sub>2</sub>O)<sub>2</sub>](BF<sub>4</sub>)<sub>2</sub>·2MeCN <b>2a</b>, and [Au<sup>III</sup>([9]aneS<sub>2</sub>O)<sub>2</sub>](ClO<sub>4</sub>)<sub>6</sub>(H<sub>5</sub>O<sub>2</sub>)(H<sub>3</sub>O)<sub>2</sub> <b>3</b> ([9]aneS<sub>2</sub>O = 1-oxa-4,7-dithiacyclononane) have been prepared and structurally characterized by single crystal X-ray crystallography. The oxidation of [Au([9]aneS<sub>2</sub>O)<sub>2</sub>]<sup>+</sup> to [Au([9]aneS<sub>2</sub>O)<sub>2</sub>]<sup>2+</sup> involves a significant reorganization of the co-ordination sphere from a distorted tetrahedral geometry in [Au([9]aneS<sub>2</sub>O)<sub>2</sub>]<sup>+</sup> [Au−S 2.3363(12), 2.3877(12), 2.6630(11), 2.7597(13) Å] to a distorted square-planar co-ordination geometry in [Au([9]aneS<sub>2</sub>O)<sub>2</sub>]<sup>2+</sup>. The O-donors in [Au([9]aneS<sub>2</sub>O)<sub>2</sub>]<sup>2+</sup> occupy the axial positions about the Au<sup>II</sup> center [Au···O = 2.718(2) Å] with the S-donors occupying the equatorial plane [Au−S 2.428(8) and 2.484(8) Å]. [Au([9]aneS<sub>2</sub>O)<sub>2</sub>]<sup>3+</sup> shows a co-ordination sphere similar to that of [Au([9]aneS<sub>2</sub>O)<sub>2</sub>]<sup>2+</sup> but with significantly shorter axial Au···O interactions [2.688(2) Å] and equatorial Au−S bond lengths [2.340(4) and 2.355(6) Å]. The cyclic voltammogram of <b>1</b> in MeCN (0.2 M NBu<sub>4</sub>PF<sub>6</sub>, 253 K) at a scan rate of 100 mV s<sup>−1</sup> shows an oxidation process at <i>E</i><sub>p</sub><sup>a</sup> = +0.74 V and a reduction process at <i>E</i><sub>p</sub><sup>c</sup> = +0.41 V versus Fc<sup>+</sup>/Fc assigned to the two-electron Au<sup>III/I</sup> couple and a second reduction process at <i>E</i><sub>p</sub><sup>c</sup> = +0.19 V assigned to the Au<sup>I/0</sup> couple. This electrochemical assignment is confirmed by coulometric and UV−vis spectroelectrochemical measurements. Multifrequency EPR studies of the mononuclear Au<sup>II</sup> complex [Au([9]aneS<sub>2</sub>O)<sub>2</sub>]<sup>2+</sup> in a fluid solution at X-band and as frozen solutions at L-, S-, X-, K-, and Q-band reveal <i>g</i><sub>iso</sub> = 2.0182 and <i>A</i><sub>iso</sub> = −44 × 10<sup>−4</sup> cm<sup>−1</sup>; <i>g</i><sub><i>xx</i></sub> = 2.010, <i>g</i><sub><i>yy</i></sub> = 2.006, <i>g</i><sub><i>zz</i></sub> = 2.037; <i>A</i><sub><i>xx</i></sub>= −47 × 10<sup>−4</sup> cm<sup>−1</sup>, <i>A</i><sub><i>yy</i></sub> = −47 × 10<sup>−4</sup> cm<sup>−1</sup>, <i>A</i><sub><i>zz</i></sub> = −47 × 10<sup>−4</sup> cm<sup>−1</sup>; <i>P</i><sub><i>xx</i></sub> = −18 × 10<sup>−4</sup> cm<sup>−1</sup>, <i>P</i><sub><i>yy</i></sub> = −10 × 10<sup>−4</sup> cm<sup>−1</sup>, and <i>P</i><sub><i>zz</i></sub> = 28 × 10<sup>−4</sup> cm<sup>−1</sup>. DFT calculations predict a singly occupied molecular orbital (SOMO) with 27.2% Au 5d<sub><i>xy</i></sub> character, consistent with the upper limit derived from the uncertainties in the <sup>197</sup>Au hyperfine parameters. Comparison with [Au([9]aneS<sub>3</sub>)<sub>2</sub>]<sup>2+</sup> reveals that the nuclear quadrupole parameters, <i>P</i><sub><i>ii</i></sub> (<i>i</i> = <i>x</i>, <i>y</i>, <i>z</i>) are very sensitive to the nature of the Au<sup>II</sup> co-ordination sphere in these macrocyclic complexes. The observed geometries and bond lengths for the cations [Au([9]aneS<sub>2</sub>O)<sub>2</sub>]<sup>+/2+/3+</sup> reflect the preferred stereochemistries of d<sup>10</sup>, d<sup>9</sup>, and d<sup>8</sup> metal ions, respectively, with the higher oxidation state centers being generated at higher anodic potentials compared to the related complexes [Au([9]aneS<sub>3</sub>)<sub>2</sub>]<sup>+/2+/3+</sup>. aneS;macrocyclic complexes;AuII;4PF;2O;reduction process;SOMO;Multifrequency EPR studies;UV;Electronic Structure Studies;cm;8 metal ions;DFT;oxidation state centers;5 dxy character 2008-11-03
    https://acs.figshare.com/articles/journal_contribution/Crystallographic_Electrochemical_and_Electronic_Structure_Studies_of_the_Mononuclear_Complexes_of_Au_I_II_III_with_9_aneS_sub_2_sub_O_9_aneS_sub_2_sub_O_1_oxa_4_7_dithiacyclononane_/2903770
10.1021/ic8010037.s001