Synthesis and Structures of Cuprous Triptycylthiolate Complexes

A synthesis of 1-(thioacetyl)triptycene (5), a convenient protected form of 1-(thiolato)triptycene [STrip](-), is described, a key transformation being the high yield conversion of tert-butyl 1-triptycenyl sulfide (8) to 5 by a protocol employing BBr3/AcCl. Syntheses of the two-coordinate copper(I) compounds [Bu4N][Cu(STrip)(2)], [Bu4N]10, and [(Cu(IMes)(STrip)] (13) proceed readily by chloride displacement from Cu Cl and [Cu(IMes)Cl], respectively. Reaction of 10 with Ph3SiSH or Me3SiI produces the heteroleptic species [Cu(STrip)(SSiPh3)](-) (11) and [Cu(STrip)I](-) (12), detected by mass spectrometry, in mixture with the homoleptic bis(thiolate) anions. Structural identification by X-ray crystallography of the ligand precursor molecules 9-(thioacetyl)anthracene (4, triclinic and orthorhombic polymorphs), tert-butyl 9-anthracenyl sulfide (7), 5, and tert-butyl 1-triptycenyl sulfide (8) are presented. Crystallographic characterization of bis(9-anthracenyl)sulfide (3), which features a C-S-C angle of 104.0 degrees and twist angle of 54.8 degrees between anthracenyl planes, is also given. A crystal structure of [Bu4N]-[(STrip)], [Bu4N]9, provides an experimental measure of 144.6 degrees for the ligand cone angle. The crystal structures of [Bu4N]10 and 13 are reported, the former of which reveals an unexpectedly small C-S center dot center dot center dot S-C torsion angle of similar to 41 (average of two values), which confers a near cis disposition of the triptycenyl groups with respect the S-Cu-S axis. This conformation is governed by interligand pi center dot center dot center dot pi and CH center dot center dot center dot pi interactions. A crystal structure of an adventitious product, [Bu4N][(Cu-STrip)(6)(mu(6)-Br)]center dot[Bu4N][PF6], [Bu4N]14 center dot[Bu4N][PF6] is described, which reveals a cyclic hexameric structure previously unobserved in cuprous thiolate chemistry. The Cu6S6 ring displays a centrosymmetric cyclohexane chair type conformation with a Br- ion residing at the inversion center and held in place by apparent soft-soft interactions with the Cu(I) ions.