A Benzodiphosphaborolediide

• Published in: Chemistry : a European journal 2021-11, Vol.27 (66), p.16342-16346
• Main Authors: Pearce, Kyle G., Canham, Elinor P. F., Nixon, John F., Crossley, Ian R.
• Format: Article
• Language: English
• Subjects: anions; boranes; borolediide; phosphacycle; phosphane
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.202103427

The first example of a diphosphaborolediide, the benzo‐fused [C6H4P2BPh]2− (12−), is prepared from ortho‐bis(phosphino)benzene (C6H4{PH2}) and dichlorophenylborane, via a sequential lithiation approach. The dilithio‐salt can be obtained as an oligomeric THF solvate or discrete TMEDA adduct, both of which are fully characterized, including by X‐ray diffraction. Alongside NICS calculations, data strongly suggest some aromaticity within 12−, which is further supported by preliminary coordination studies that demonstrate η5‐coordination to a zerovalent molybdenum center, as observed crystallographically for the oligomeric [{Mo(CO)3(η5‐1)}{μ‐η1‐Mo(CO)3(TMEDA)}2] ⋅ [μ‐Li(THF)][μ‐Li(TMEDA)]. The 1,3‐diphosphaborolediide ligand motif, a hitherto missing member of the “hetero‐Cp“ family, is obtained within an indenyl scaffold as its dilithium salt, as both thf and TMEDA solvates. This dianionic ligand exhibits aromaticity commensurate with its hybrid phospholide‐borolediide nature, as is determined by NICS calculations and observed experimentally for both lithium salts. Additionally, coordination to zero‐valent molybdenum is achieved, demonstrating a capacity to to coordinate readily as a π‐ and bridging π‐,σ‐type ligand.