Mono- and Dinuclear Transition Metal Complexes of the Hexadentate Ligand Tris(4-tert-butyl-2-mercaptobenzyl)-1,4,7-triazacyclononane (L)

Abstract

The hexadentate, pendant arm macrocycle 1,4,7-tris(4-tert-butyl-2-mercaptobenzyl)-1,4,7-triazacyclononane (H(3)L) has been synthesized and isolated as its trihydrochloride, H(3)L.3HCl, or sodium salt, Na(3)L, and its coordination chemistry with first-row transition metals has been studied. Mononuclear complexes of the type [LM(III)] (M = Ga (1), In (2), V (3), Cr (4), Mn (5), Fe,Co (6)) have been isolated as have the one-electron-oxidized forms [LM]PF(6) (M = V(IV) (3a), Mn(IV) (5a)). The crystal structure of 6 has been determined by single-crystal X-ray crystallography. Complex 6 crystallizes in the orthorhombic space group Iba2, with cell constants a = 14.206(8) Å, b = 22.53(1) Å, c = 26.07(1) Å, V = 8344.0(3) Å(3), and Z = 8. The cobalt(III) ion is in a distorted octahedral fac-N(3)S(3) donor set. The reaction of L with divalent metal chlorides in a 1:2 ratio in methanol affords the homodinuclear complexes [LM(II)(2)Cl] (M = Mn (7), Co (8), Ni (9), Zn (10), Cd (11)) where one metal is six- (N(3)MS(3)) and the other is four-coordinate (S(3)MCl); the two polyhedra are linked by three &mgr;(2)-thiolato bridges. Heterodinuclear complexes of the type [LM(1)M(2)Cl] have been obtained from [LM(2)Cl] species by abstraction of the four-coordinate metal ion and replacement by a different metal ion. The complexes [LZn(II)M(II)Cl] (M = Fe (12), Co (13), Ni (14)), [LNi(II)M(II)Cl] (M = Co (15), Zn (16)), and [LMn(II)M(II)Cl] (M = Fe (17), Co (18), Ni (19), Zn (20), Cd (21), Hg (22)) have been isolated as solid materials. The crystal structure of 14 has been determined by X-ray crystallography. Complex 14 crystallizes in the orthorhombic space group P2(1)2(1)2(1), with cell constants a = 15.45(1) Å, b = 17.77(1) Å, c = 17.58(1) Å, V = 4826.5(4) Å(3), and Z = 4. The linkage isomers 14 and 16 show characteristic electronic spectra for octahedrally and tetrahedrally coordinated Ni(II), respectively. The electronic structures of new complexes have been investigated by UV-vis spectroscopy; their magnetochemistry and electrochemistry are reported.

A Paramagnetic Copper(III) Complex Containing an Octahedral CuIIIS6 Coordination Polyhedron

“…They are the same as observed in diamagnetic, mononuclear [Co III L]. [4] The 6 ) 2 does not display any redox activity in the potential range 0.7 to À 1.1 V versus Fc /Fc. Temperature-dependent magnetic susceptibility measurements (SQUID, 2 ± 300 K; 1.0 T) on powdered samples revealed a temperature-independent magnetic moment of 1.74 m B (10 ± 300 K) for 1-(PF 6 ) 2 and slightly temperaturedependent moments between 2.4 and 2.6 m B (20 ± 300 K) for 2-(ClO 4 ) 3´2 Me 2 CO in reasonable agreement with the expected spin-only values for Cu II (S 1 2) and high-spin Cu III ions (S 1).…”

“…The reaction of mononuclear [Co III L], [4] in which L 3À is the hexadentate macrocyclic trianion 1,4,7-tris(4-tert-butyl-2-sulfidobenzyl)-1,4,7-triazacyclononane, with Cu II (OAc) 2´H2 O (2:1) in methanol affords upon addition of NaPF 6 red crystals of the heterotrinuclear complex 1-(PF 6 [5] (tacn 1,4,7-triazacyclononane) and addition of NaClO 4 yields blue-black microcrystals of 2-(ClO 4 ) 3´2 Me 2 -CO. Complex 2 is stable in the solid state for weeks but decomposes rapidly within minutes in solution (reduction).…”

Molecular and Electronic Structure of Two Linear Thiophenolate-Bridged Heterotrinuclear Complexes [LFeRuFeL]2+/3+ (L = 1,4,7-Tris(4-tert-butyl-2-mercaptobenzyl)-1,4,7-triazacyclononane)

“…In order to obtain dition of NaPF 6 , brown microcrystals of [LFeRuFeL]-(PF 6 ) 2 · 3 CH 3 OH (1) were obtained. Recrystallization of a better understanding of their electronic structure, we decided that it would be of value to investigate the isoelec-this material from acetone/acetonitrile (1:1) and addition of Na [BPh 4 ] afforded single crystals of [{LFe} 2 Ru]-tronic heterotrinuclear analogs [LFeRuFeL] 2ϩ/3ϩ . Here we report the synthesis, the molecular and electronic structures, (BPh 4 ) 2 · CH 3 CN · 3 (CH 3 ) 2 CO.…”

“…We have conScheme 2. Schematic MO representation for [{LFe} 2 Ru] 2ϩ/3ϩ clusively shown [3] that the iron ions in [LFeCr III FeL] 3ϩ are purely low-spin ferric ions (oxidation state ϩIII), whereas in [LFeCr III FeL] 1ϩ they are low-spin ferrous (ϩII) and in [LFeCr III FeL] 2ϩ are a mixed valent species with delocalized strong antiferromagnetic coupling (J a < Ϫ400 cm Ϫ1 ) has been rationalized as originating from direct exchange beelectronic structure (two Fe 2.5 ions). A plot of the corresponding 57 Fe-isomer shift vs the formal oxidation state is tween local a 1 -orbitals and the onset of metalϪmetal bonding.…”

“…Electron delocalization in [{LFe} 2 Fe] 2ϩ refinement, and artwork of the structure which was readily solved and refined by direct methods and difference Fourier techniques. All non-hydrogen atoms were refined anisotropically except the small size of a cobalt(III) ion (the overlap of a 1 orbitals is methyl carbon atoms of one disordered acetonitrile and acetone very poor).…”