Rhenium Biscorrole Sandwich Compounds: XAS Evidence for a New Coordination Motif

The high-temperature interaction of free-base meso-triarylcorroles with Re-2(CO)(10) has led toputative rhenium biscorrole sandwich compounds with the formula ReH-[Cor](2) (Cor = corrole). Density functional theory calculations andRe L-3-edge extended X-ray absorption fine structure measurementssuggest a seven-coordinate metal center, with the extrahydrogen residing on one of the corrole nitrogens. The interaction of three free-base meso-tris-(p-X-phenyl)-corroles H-3[TpXPC](X = H, CH3, OCH3) with Re-2(CO)(10) at 235 degrees C in the presence of K2CO3 in o-dichlorobenzene has led to putative rheniumbiscorrole sandwich compounds with the formula ReH-[TpXPC](2). Density functional theory calculations and Re L-3-edge extended X-ray absorption fine structure measurementssuggest a seven-coordinate metal center, with the extrahydrogen located on one of the corrole nitrogens. The complexes canbe deprotonated by a base such as 1,8-diazabicyclo[5.4.0]-undec-7-ene,resulting in a substantial sharpening of the UV-vis spectraand split Soret bands, consistent with the generation of C (2)-symmetric anions. Both the seven-coordinate neutraland eight-coordinate anionic forms of the complexes represent a newcoordination motif in the field of rhenium-porphyrinoid interactions.

Automated summary

The high-temperature interaction between free-base meso-triarylcorroles and Re-2(CO)(10) leads to the formation of rhenium biscorrole sandwich compounds. Density functional theory calculations and Re L-3-edge extended X-ray absorption fine structure measurements indicate a seven-coordinate metal center, with the extra hydrogen atom located on one of the corrole nitrogens.