Synthesis and Reactivity Studies of Main Group Corrole Complexes

Abstract

Previous studies on boron corrole (cor) complexes showed that boron porphyrin chemistry is not just replicated, and the new and unexpected chemistry leads to further investigations in this area. The previously suggested monoboron corrole complexes are fully established, showing the shortest BH···HN dihydrogen bonding reported so far, which in PhBH(H2TPFP)C has bond lengths of 1.540 Å and 1.611 Å, respectively. The complex PhBF(H2TPFP)C and further examples of the type BF2(H2cor) are established, showing internal BF···HN interactions that stabilise these complexes, which is supported by DFT calculations. Further examples of the bridging hydride complex PhBHBPh(cor) were established (PhBHBPh(TPFP)C, PhBHBPh(Mes2-p-OMeP)C and PhBHBPh(Br8-4-CF3-P)C). PhBHBPh(TT)C was used to investigate the subsequent formation of PhBB(cor) by 1H NMR studies to follow the thermal induced loss of benzene to form PhBB(cor) and to establish the consequent oxidation to PhBOB(cor). DFT calculations were perfomed to explain the reactivity of PhBB(cor) and to identify the structural confirmation of this complex. New examples of [HNEt(iPr)2][FBOBF(cor)] were prepared and quantum yield studies were conducted to investigate the fluorescence properties of selected corrole complexes, showing a very high fluorescence quantum yield for [HNEt(iPr)2][FBOBF(TPFP)C]. The scope of group 1 corrole complexes was extended by further examples of lithium corroles, Li3(TPFP)C(THF)6 and Li3(TT)C(THF)6, and the heavier alkali metals, sodium and potassium. Mass spectrometer analysis and UV-vis spectroscopy suggest the formation of Na2(Hcor)(THF)3 and K2(Hcor)(THF). The first examples of selenium, tellurium and iodine corrole complexes were prepared, using Li3(cor)(THF)6 as precursor. Characterisation proved to be difficult as a result of the extreme moisture sensitivity of these complexes, showing that the TPFPC is the most stable corrole ligand for these complexes. Mass spectrometer analysis suggested the formation of dimeric complexes with briding chlorides, [Se(cor)]2Cl2 and [Te(cor)]2Cl2, which was confirmed by DFT calculations to be the most stable formulation. The iodine corrole complex, [I(cor)Cl2]2, shows an isoelectronic structure to the only analogous tellurium porphyrin complex, by going through in unexpected oxidation of the iodine (III to IV).