Crystal and molecular structures of fac-[Re(Bid)(PPh3)(CO)3] [Bid is tropolone (TropH) and tribromotropolone (TropBr3H)].

Abstract

Two rhenium complexes, namely, fac-tricarbonyl(triphenylphosphane-κP)(tropolonato-κ²O,O')rhenium(I), [Re(C₇H₅O₂)(C₁₈H₁₅P)(CO)₃] or fac-[Re(Trop)(PPh₃)(CO)₃] (1), and fac-tricarbonyl(3,5,7-tribromotropolonato-κ²O,O')(triphenylphosphane-κP)rhenium(I), [Re(C₇H₂Br₃O₂)(C₁₈H₁₅P)(CO)₃] or fac-[Re(TropBr₃)(PPh₃)(CO)₃] (2) (TropH is tropolone and and TropBr₃H is tribromotropolone), were synthesized and their crystal and molecular structures confirmed by single-crystal X-ray diffraction. Both crystallized in the space group P-1 and display an array of inter- and intramolecular interactions which were confirmed by solid-state ¹³C NMR spectroscopy using cross polarization magic angle spinning (CPMAS) techniques, as well as Hirshfeld surface analysis. The slightly longer Re-P distance of 1 [2.4987 (5) versus 2.4799 (11) Å for 1 and 2, respectively] suggests stronger back donation from the carbonyl groups in the former case, possibly due to the stronger electron-donating ability of the unsubstituted tropolonate ring system. However, this is not supported in the Re-CO bond distances of 1 and 2.