Synthesis and Characterization of Homo- and Heterodinuclear Complexes Containing the N3M(2-SR)3MN
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- 作者：Berthold Kersting ; Dieter Siebert ; Dirk Volkmer ; Mario J. Kolm ; and Christoph Janiak
- 刊名：Inorganic Chemistry
- 出版年：1999
- 出版时间：August 23, 1999
- 年：1999
- 卷：38
- 期：17
- 页码：3871 - 3882
- 全文大小：199K
- 年卷期：v.38,no.17(August 23, 1999)
- ISSN：1520-510X
文摘
A novel amine-thiolate ligand, H33·6HCl (N,N',N''-tris-[2-thio-3-aminomethyl-5-tert-butylbenzyl]-1,1,1-tris(aminomethyl)ethane), has been synthesized and used in the preparation of dinuclear complexes of Fe, Co, andNi. The nonadentate N6S3 ligand H33 is formally derived from the symmetric tridentate N2S ligand H11 (2,6-bis(aminomethyl)-4-tert-butylthiophenol). It provides two dissimilar octahedral N3S3 and N'3S3 coordination sitesto give complexes with a central N3M(
2-SR)3MN'3 core structure (N and N' denote primary and secondaryamine nitrogen atoms, respectively). The complexes of H33 exist as dinuclear [MII2(3)]+, [MIIIMII(3)]2+, or [MIII2(3)]3+ species which are all accessible by chemical or electrochemical reduction/oxidation. The following complexeswere isolated as microcrystalline solids: [CoIII2(3)][ClO4]3 (4b), [NiIIINiII(3)][BPh4]2 (5b), and [FeIIIFeII(3)][BPh4]2(6b). The chemical and physicochemical properties of the respective species are very similar to those of Fe, Co,and Ni complexes of H11, [M2(1)3]n+ (M = Co, n = 3, (4a); M = Ni, n = 2 (5a); M = Fe, n = 2 (6a)), andsupport the formulation of 4b-6b as discrete dinuclear species with a central N3M(2-SR)3MN'3 core. NMRspectra of diamagnetic cobalt complexes 4a and 4b reveal the complexes to be C3h and C3 symmetric, respectively,in the solution state. The crystal structure determination of [CoIII2(1)3][Fe(CN)6]·7MeOH·3H2O (4c) (monoclinic,space group C2/c, a = 28.037(2) Å, b = 17.861(1) Å, c = 25.727(2) Å, 
= 90.24(1)
, and Z = 8) reveals 4cto consist of dinuclear [CoIII2(1)3]3+ trications featuring two fac-octahedral N3CoIII(SR)3 units bridged at the thiolatesulfur atoms. Compound 4c represents the first structurally characterized MIII2 complex of H11. The ability ofH33 to form heterodinuclear complexes is demonstrated with the synthesis of [CoIIINiII(3)][BPh4]2 (7) and itslinkage isomer [NiIICoIII(3)][BPh4]2 (8). All complexes undergo two electrochemically and chemically reversibleone-electron-transfer reactions which convert the respective [M2(3)]n+ species. For MIII2/MIIIMII (E11/2) and MIIIMII/MII2 (E21/2): -0.40 V, -0.84 V (M = Co), +0.49 V, +0.05 V (M = Ni), +0.21 V, -0.33 V (M = Fe) vs SCE.Heterodinuclear complexes 7 and 8 also give rise to two consecutive one-electron-transfer processes at E11/2(NiIII/II) and E21/2 (CoIII/II): +0.55 V, -0.71 V (for 7) and +0.60 V, -0.86 V (for 8), respectively. Comparisonof the electrochemical properties of [CoIIINiII(3)]2+ and [NiIIINiII(3)]2+ reveals the NiIII/II redox potential in thedinuclear complexes to be influenced by the oxidation state of the adjacent metal ion. At 77 K the mixed-valentNiIIINiII (S = 3/2 spin ground states) and FeIIIFeII complexes (S = 1/2 spin ground states) exhibit localized anddelocalized valencies, respectively, as indicated by UV-vis, EPR, and 57Fe Mössbauer spectroscopy.
2-SR)3MN'3 core structure (N and N' denote primary and secondaryamine nitrogen atoms, respectively). The complexes of H33 exist as dinuclear [MII2(3)]+, [MIIIMII(3)]2+, or [MIII2(3)]3+ species which are all accessible by chemical or electrochemical reduction/oxidation. The following complexeswere isolated as microcrystalline solids: [CoIII2(3)][ClO4]3 (4b), [NiIIINiII(3)][BPh4]2 (5b), and [FeIIIFeII(3)][BPh4]2(6b). The chemical and physicochemical properties of the respective species are very similar to those of Fe, Co,and Ni complexes of H11, [M2(1)3]n+ (M = Co, n = 3, (4a); M = Ni, n = 2 (5a); M = Fe, n = 2 (6a)), andsupport the formulation of 4b-6b as discrete dinuclear species with a central N3M(2-SR)3MN'3 core. NMRspectra of diamagnetic cobalt complexes 4a and 4b reveal the complexes to be C3h and C3 symmetric, respectively,in the solution state. The crystal structure determination of [CoIII2(1)3][Fe(CN)6]·7MeOH·3H2O (4c) (monoclinic,space group C2/c, a = 28.037(2) Å, b = 17.861(1) Å, c = 25.727(2) Å, = 90.24(1), and Z = 8) reveals 4cto consist of dinuclear [CoIII2(1)3]3+ trications featuring two fac-octahedral N3CoIII(SR)3 units bridged at the thiolatesulfur atoms. Compound 4c represents the first structurally characterized MIII2 complex of H11. The ability ofH33 to form heterodinuclear complexes is demonstrated with the synthesis of [CoIIINiII(3)][BPh4]2 (7) and itslinkage isomer [NiIICoIII(3)][BPh4]2 (8). All complexes undergo two electrochemically and chemically reversibleone-electron-transfer reactions which convert the respective [M2(3)]n+ species. For MIII2/MIIIMII (E11/2) and MIIIMII/MII2 (E21/2): -0.40 V, -0.84 V (M = Co), +0.49 V, +0.05 V (M = Ni), +0.21 V, -0.33 V (M = Fe) vs SCE.Heterodinuclear complexes 7 and 8 also give rise to two consecutive one-electron-transfer processes at E11/2(NiIII/II) and E21/2 (CoIII/II): +0.55 V, -0.71 V (for 7) and +0.60 V, -0.86 V (for 8), respectively. Comparisonof the electrochemical properties of [CoIIINiII(3)]2+ and [NiIIINiII(3)]2+ reveals the NiIII/II redox potential in thedinuclear complexes to be influenced by the oxidation state of the adjacent metal ion. At 77 K the mixed-valentNiIIINiII (S = 3/2 spin ground states) and FeIIIFeII complexes (S = 1/2 spin ground states) exhibit localized anddelocalized valencies, respectively, as indicated by UV-vis, EPR, and 57Fe Mössbauer spectroscopy.