The new hexadentate macrocycle containing three phenolate pendant arms has been prepared from 1,4,7-triazacyclononane and 3 equiv of 2-bromomethyl-4-tert-butylphenyl acetate: Tripotassium l,4,7-tris(5-tert-butyl-2-hydroxybenzyl)-1,4,7-triazacyclononanate (K3L; C39H54N3O3K3). The reaction of trivalent first-row transition metals with the trianion affords monomeric pseudooctahedral complexes, of which the following have been characterized: LVIII (2); LCrIII (5); LMnIII (6); LFeIII (8); LCoIII (9). Monocationic complexes containing a tetravalent metal ion have also been prepared: [LTiIV]PF6; [LVIV](ClO4) (3); [LMnIV]BPh4 (7). [LVV](ClO4)2 (4) has been synthesized by oxidation of 2 or by reaction of NH4VO3 and K3L in acidic CH3CN solution. In acidic methanolic solutions of 5, 8, and 9 dimeric species were obtained as crystalline solids: [(LH)2MIII2](ClO4)2·2H2O (M = CrIII (10), FeIII (11), CoIII (12)). The crystal structures of [LTiIV]BPh4, 5, 8, and 11 have been determined by X-ray crystallography: [LTi]BPh4, orthorhombic, space group P212121, a = 10.856(6) Å, b = 19.33(2) Å, c = 26.49(2) Å, Z = 4; 5, trigonal, space group R3, a = 23.547(3) Å, c = 6.521(1) Å, Z = 3; 8, trigonal, space group R3, a = 23.64(2) Å, c = 6.599(7) Å, Z = 3; 11, monoclinic, space group P21/n, a = 16.48(1) Å, b = 13.78(1) Å, c = 17.84(1) Å, β = 93.72(6)°; Z = 2. Electronic spectral data, magnetic properties, and the electrochemistry of the new complexes are reported. The dπ-pπ bonding of the phenolate-metal M-O bonds is analyzed as a function of the dn electronic configuration of the respective metal ion.