Rhenium Complexes with Weakly Coordinating Solvent Ligands, cis-[Re(PR₃)(CO)₄(L)][BArF], L = CH₂Cl₂, Et₂O, NC₅F₅:  Decomposition to Chloride-Bridged Dimers in CH₂Cl₂ Solution

The solvent-coordinated complexes [ cis -Re(CO) 4 (PR 3 )(S)][BAr F ] (R = Ph, i Pr, Cy, BAr F = [B(3,5-(CF 3 ) 2 C 6 H 3 ) 4 ] - ) for S = Et 2 O, CH 2 Cl 2, and NC 5 F 5 have been prepared from reaction of the neutral methyl precursors, cis -Re(CO) 4 (PR 3 )(Me), with either [H(OEt 2 ) 2 ][BAr F ] or [Ph 3 C][BAr F ] in the appropriate solvent. A crystal structure of the complex [ cis -Re(CO) 4 (P i Pr 3 )(ClCH 2 Cl)][BAr F ] shows that the dichloromethane ligand is coordinated through one chlorine, with an Re−Cl distance of 2.554(2) Å. The first example of a structurally characterized pentafluoropyridine complex of rhenium was also determined, [ cis -Re(CO) 4 (P i Pr 3 )(NC 5 F 5 )][BAr F ], with an Re−N distance of 2.319(5) Å. Activation of C−Cl bonds in the dichloromethane complexes result in the formation of the chloride-bridged dimers, {[ cis -Re(CO) 4 (PR 3 )] 2 (μ-Cl)}{BAr F }, and the X-ray structures of the Ph and Cy derivatives were determined.