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Complexes containing manganese-oxygen bonds have been implicated in a variety of biological and synthetic processes. Herein, we describe the synthesis of a family of stable, high-spin trigonal bipyramidal manganese complexes of the electronically flexible ligand tris(5-cyclohexylimino-pyrrol-2-ylmethyl)amine [H3N(pi(Cy))3] featuring apical water, hydroxyl, and oxo ligands. Terminal Mn(III)-O complexes are rare and the formation of this species was achieved from a variety of reagents including O2, PhIO and NO2(-). Described herein is the preparation, structural and electronic properties of these manganese complexes.

The synthesis of a novel dipodal ligand framework, H2[(Me)N(pi(Cy))2], is summarized. Upon metalation with MCl2 salts (M = Fe, Cu), the ligand undergoes a conformational change, resulting in the formation of a trigonal bipyramidal metal center with a pseudoplanar, meridionally-bound ligand framework. This tautomerization positions pendant amines in the metal's secondary coordination sphere. Metalation with M(OTf)2 in coordinating solvent yields octahedral metal complexes, where two solvent molecules bind in the apical positions with one outer sphere counter ion. Reactivity of these complexes, ((Me)N(afa(Cy))2)M(X)2 (X = Cl, OTf), with 2,2'-bypyridine results in ligand reorganization, yielding a facial coordination geometry of the dipodal framework. The described complexes have been characterized by (1)H NMR, EPR, IR, Mössbauer and electronic absorption spectroscopies as well as X-ray crystallography.

Rhenium-(V), -(VI) and -(VII) complexes of the [α2-P2W17O61]10– isomer, a mono-lacunary derivative of the [α-P2W18O62]6– (Wells–Dawson) ion have been prepared and characterized by multinuclear NMR spectroscopy, electrospray mass spectrometry and electron paramagnetic resonance spectroscopy, among other techniques. The molecules have the formulation [α2-ReOP2W17O61]n–, where n = 7,6,5 for ReV, ReVI and ReVII, respectively. 183W NMR spectroscopy for the ReV and ReVII analogs shows that the molecules have Cs symmetry, as expected for substitution in the α2 site. Simulations of the X-band and Q-band EPR spectra of the ReVI analog, using Cs symmetry, allow determination of the g, hyperfine and quadrupole coupling tensors. X-Band, Q-band and W-band EPR spectroscopy show extreme variations in linewidths due to random strains or distortions of the complex.