Bis(triphenylphosphine)gold(I) Perrhenate

Abstract

Dedicated to Professor Bernd Krebs on the occasion of his 75 th birthdayBis(triphenylphosphine)gold(I) perrhenate [Ph 3 PAuPPh 3 ] + ReO 4 − has been prepared in high yield from Ph 3 PAuCl, Ph 3 P and AgReO 4 in a mixed solvent. The compound is stable in air and decomposes at 235 • C. In the crystal structure, the two independent perrhenate anions are not approaching the gold centers of the two independent cations, but weak interionic interactions are entertained via π-π stacking of phenyl groups and C-H···O contacts. As three-blade chiral rotors, the Ph 3 P ligands of the cations are in a staggered conformation at the gold atoms with only slightly bent P-Au-P axes. IR and NMR data show no anomalies and are close to those of alkali or onium perrhenates.

Bis(triphenylphosphine)silver(i) perrhenate, a cyclic dimer

“…In a report published in 2013 on complexes with triphenylphosphine as the ligand it has been shown that in the 1 : 2 complex, [(Ph 3 P) 2 Au] + ReO 4 À , the gold center has no acceptor affinity for the anion and remains strictly linearly two-coordinate. 29 This result has recently been confirmed for a series of other gold(I) complexes with tertiary phosphines, where again the ReO 4…”

“…In a report published in 2013 on complexes with triphenylphosphine as the ligand it has been shown that in the 1 : 2 complex, [(Ph 3 P) 2 Au] + ReO 4 À , the gold center has no acceptor affinity for the anion and remains strictly linearly two-coordinate. 29 This result has recently been confirmed for a series of other gold(I) complexes with tertiary phosphines, where again the ReO 4 À counterion is not part of the coordination sphere of the metal atoms. 30 In subsequent investigations attempts have been made to synthesize the corresponding silver(I) complexes, where perrhenate complexation and hence activation may arise because relativistic effects, which strongly favour two-coordination at gold(I), are strongly reduced at silver(I) centres.…”

“…in the ESI †). À tetrahedron which is present in the gold analogue [1.710(7)-1.716(7) Å] 29. However, it is interesting to note that in crystals of AgReO 4 (Scheelite-type), where all four oxygen atoms of the anion are in close contact with the silver cations,5 the Re-O distances are as long as 1.732(2) Å, showing the strong influence of silver multiple-coordination on the structure of the anion.…”