Phosphorus‒bismuth peri-substituted acenaphthenes : a synthetic, structural and computational study

Abstract

A series of acenaphthene species with a diisopropylphosphino group and a variety of bismuth functionalities in the peri-positions were synthesised and fully characterised, including single crystal X–ray diffraction. The majority of the reported species feature a relatively rare interpnictogen P−Bi bond. The series includes the phosphine¬−bismuthine, Acenap(PiPr2)(BiPh2) 2 (Acenap = acenaphthene-5,6-diyl), which was subjected to a fluorodearylation reaction to produce Acenap(PiPr2)(BiPhX) 5−8 and 10 (X = BF4-, Cl, Br, I, SPh), displaying varying degrees of ionicity. The geminally bis(acenaphthyl) substituted [Acenap(PiPr2)2]BiPh 3 shows a large through-space coupling of 17.8 Hz, formally 8TSJPP. Coupling deformation density (CDD) calculations confirm the double through-space coupling pathway, in which the P and Bi lone pairs mediate communication between the two 31P nuclei. Several synthetic routes towards the phosphine−diiodobismuthine Acenap(PiPr2)(BiI2) 9 have been investigated, however the purity of this, surprisingly thermally stable potential synthon, remains poor.