This paper presents aspects of the coordination chemistry of mono- and divalent manganese complexes supported by the anionic tris(phosphino) borate ligand, [PhBP3iPr] (where [PhBP3iPr] = [PhB(CH(2)P(iP)r(2))(3)](-)). The Mn(II) halide complexes, [PhBP3iPr] MnCl (1) and [PhBP3iPr]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: [PhBP3iPr]Mn(N-3) (3), [PhBP3iPr]Mn(CH2Ph) (4), [PhBP3iPr]Mn(Me) (5), [PhBP3iPr]Mn(NH(2,6-(Pr2C6H3)-Pr-i)) (6), [PhBP3iPr]Mn(dbabh) (7), and [PhBP3iPr]Mn(1-Ph(isoindolate)) (8). The complexes 2-8 feature a divalentmetal 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 TI-Mn adduct [PhBP3iPr]TI-MnBr(CO)(4) (9) and the octahedral complex [PhBP3iPr]Mn((CNBu)-Bu-t)(3) (10). Some of our initial synthetic efforts to generate [PhBP3iPr]Mn N-x species are briefly described, as are DFT studies that probe the electronic viability of these types of multiply bonded target structures.