1ST-ROW TRANSITION-METAL COMPLEXES OF THE HEXADENTATE MACROCYCLE 1,4,7-TRIS(5-TERT-BUTYL-2-HYDROXYBENZYL)-1,4,7-TRIAZACYCLONONANE (LH3) - CRYSTAL-STRUCTURES OF [LTI(IV)]BPH4, [LCR(III)], [LFE(III)], AND [(LH)2FE(III)2](CLO4)2.2H2O

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 1,4,7-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: LV(III) (2); LCr(III) (5); LMn(III) (6); LFe(III) (8); LCo(III) (9). Monocationic complexes containing a tetravalent metal ion have also been prepared: [LTi(IV)]PF6; [LV(IV)](ClO4) (3); [LMn(IV)]BPh4 (7). [LV(V)](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)2M(III)2](ClO4)2.2H2O (M = Cr(III) (10), Fe(III) (11), Co(III) (12)). The crystal structures of [LTi(IV)] BPh4, 5, 8, and 11 have been determined by X-ray crystallography: [LTi]BPh4, orthorhombic, space group P2(1)2(1)2(1), a = 10.856(6) angstrom, b = 19.33(2) angstrom, c = 26.49(2) angstrom, z = 4; 5, trigonal, space group R3, a = 23.547(3) angstrom, c = 6.521(1) angstrom, Z = 3; 8, trigonal, space group R3, a = 23.64(2) angstrom, c = 6.599(7) angstrom, Z = 3; 11, monoclinic, space group P2(1)/n, a = 16.48(1) angstrom, b = 13.78(1) angstrom, c = 17.84(1) angstrom, beta = 93.72(6)-degrees; Z = 2. Electronic spectral data, magnetic properties, and the electrochemistry of the new complexes are reported. The d(pi)-p(pi) bonding of the phenolate-metal M-O bonds is analyzed as a function of the d(n) electronic configuration of the respective metal ion.