Pseudotetrahedral manganese complexes supported by the anionic tris(phosphino)borate ligand [PhBP(iPr)3

This paper presents aspects of the coordination chemistry of mono- and divalent manganese complexes supported by the anionic tris(phosphino)borate ligand, PhBP(i)(Pr)3] (where PhBP(i)(Pr)3] = PhB(CH(2)P(i)Pr2)3]-). The Mn(II) halide complexes, PhBP(i)(Pr)3]MnCl (1) and PhBP(i)(Pr)3]MnI (2), have been characterized by X-ray diffraction, SQUID magnetometry, and EPR spectroscopy. Compound 2 serves as a precursor to a series of Mn azide, alkyl, and amide species: PhBP(i)(Pr)3]Mn(N3) (3), PhBP(i)(Pr)3]Mn(CH2Ph) (4), PhBP(i)(Pr)3]Mn(Me) (5), PhBP(i)(Pr)3]Mn(NH(2,6-(i)Pr2-C6H3)) (6), PhBP(i)(Pr)3]Mn(dbabh) (7), and PhBP(i)(Pr)3]Mn(1-Ph(isoindolate)) (8). The complexes 2-8 feature a divalent-metal center and are pseudotetrahedral. They collectively represent an uncommon structural motif for low-coordinate, polyphosphine-supported Mn complexes. Two Mn(I) species have also been prepared. These include the Tl-Mn adduct PhBP(i)(Pr)3]Tl-MnBr(CO)4 (9) and the octahedral complex PhBP(i)(Pr)3]Mn(CN(t)Bu)3 (10). Some of our initial synthetic efforts to generate PhBP(i)(Pr)3]MnN(x) species are briefly described, as are DFT studies that probe the electronic viability of these types of multiply bonded target structures.