Pseudotetrahedral manganese complexes supported by the anionic tris(phosphino)borate ligand PhBPiPr3

摘要

This paper presents aspects of the coordination chemistry of mono- and divalent manganese complexes supported by the anionic tris(phosphino)borate ligand, [PhBP^iPr3] (where [PhBP^iPr3] = [PhB(CH2PⁱPr2)3]⁻). The Mn(II) halide complexes, [PhBP^iPr3]MnCl (>1 and [PhBP^iPr3]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^iPr3]Mn(N3) (>3), [PhBP^iPr3]Mn(CH2Ph) (>4), [PhBP^iPr3]Mn(Me) (>5), [PhBP^iPr3]Mn(NH(2,6-ⁱPr2-C6H3)) (>6), [PhBP^iPr₃]Mn(dbabh) (>7), and [PhBP^iPr₃]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^iPr₃]Tl-MnBr(CO)₄ (>9), and the octahedral complex [PhBP^iPr₃]Mn(CN^tBu)₃ (>10). Some of our initial synthetic efforts to generate [PhBP^iPr₃]Mn≡N_x species are briefly described, as are DFT studies that probe the electronic viability of these types of multiply bonded target structures.