Comparison of hydroxycarboxylato imidazole molybdenum(iv) complexes and nitrogenase protein structures: indirect evidence for the protonation of homocitrato FeMo-cofactors. Issue 22 (22nd May 2018)

• Record Type: Journal Article
• Authors: Wang, Si-Yuan; Jin, Wan-Ting; Chen, Hong-Bin; Zhou, Zhao-Hui
• Is Part Of: Dalton transactions. Volume 47:Issue 22(2018)
• Page Start: 7412
• Page End: 7421
• Publication Date: 2018-05-22
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c8dt00278a
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Glycolato and lactato imidazole molybdenum(iv ) complexes are used for structural comparison with FeMo-cofactors of MoFe-protein structures. Abstract : Glycolato and R, S -lactato imidazole molybdenum(iv ) complexes [Mo3 SO3 (glyc)2 (im)5 ]·im·H2 O (1 ), Na2 [Mo3 SO3 ( R, S -lact)3 (im)3 ]·10H2 O (2 ), and [Mo6 O10 ( R, S -lact)2 (im)10 ]·16H2 O (3 ) have been isolated and characterized (H2 glyc = glycolic acid, H2 lact = lactic acid, im = imidazole). α-Alkoxy coordination with molybdenum [Mo–Oα-alkoxy 1.993(7)av Å] in1 and2 showed obvious differences to their counterpart with α-hydroxy coordination [MoIV3S4 (PPh3 )3 (Hlact)2 (lact)] [2.204(4)av Å] as shown in M. N. Sokolov, S. A. Adonin, A. V. Virovets, P. A. Abramov, C. Vicent, R. Llusar and V. P. Fedin, Inorg. Chim. Acta, 2013, 395, 11–18. This was also true for the 36 reported structures of FeMo-cofactors in the RCSB protein data bank (Mo–Oav 2.272 Å), which can serve as indirect evidence for the protonation of homocitrate in FeMo-co. The C–OHα-hydroxy bonds were longer than the short C–Oα-alkoxy bonds. Trinuclear Mo3 SO3 cores were stabilized by imidazoles and/or α-hydroxycarboxylates, whereas only two glycolates were present in1 . α-Hydroxycarboxylates in1 and2 acted as bidentate ligands of Mo(iv ) atoms through α-alkoxy and α-carboxy groups, while the imidazoles coordinated monodentately with nitrogen atoms. The lactates in3 coordinated with Mo(iv ) atoms through two oxygen atoms of α-carboxy groups, leaving the α-hydroxy group free. Furthermore, novel hexanuclear oxomolybdenum(v ) malate Na6 [(Mo2 O4 )3 (mal)4 ]·5H2 O (4 ) was also isolated (H3 mal = malic acid). Solid-state and solution 13 C NMR resonances of carbon atoms in α-alkoxy groups appeared in a high-field region (71.6, 77.4 ppm), indicating that α-alkoxy groups were easy to protonate.