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Comparison of hydroxycarboxylato imidazole molybdenum(iv) complexes and nitrogenase protein structures: indirect evidence for the protonation of homocitrato FeMo-cofactors

Comparison of hydroxycarboxylato imidazole molybdenum(iv) complexes and nitrogenase protein... Glycolato and R,S-lactato imidazole molybdenum(iv) complexes [Mo3SO3(glyc)2(im)5]imH2O (1), Na2[Mo3SO3(R,S-lact)3(im)3]10H2O (2), and [Mo6O10(R,S-lact)2(im)10]16H2O (3) have been isolated and characterized (H2glyc = glycolic acid, H2lact = lactic acid, im = imidazole). -Alkoxy coordination with molybdenum [MoO-alkoxy 1.993(7)av ] in 1 and 2 showed obvious differences to their counterpart with -hydroxy coordination [MoIV3S4(PPh3)3(Hlact)2(lact)] [2.204(4)av ] 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, 1118. This was also true for the 36 reported structures of FeMo-cofactors in the RCSB protein data bank (MoOav 2.272 ), which can serve as indirect evidence for the protonation of homocitrate in FeMo-co. The COH-hydroxy bonds were longer than the short CO-alkoxy bonds. Trinuclear Mo3SO3 cores were stabilized by imidazoles and/or -hydroxycarboxylates, whereas only two glycolates were present in 1. -Hydroxycarboxylates in 1 and 2 acted as bidentate ligands of Mo(iv) atoms through -alkoxy and -carboxy groups, while the imidazoles coordinated monodentately with nitrogen atoms. The lactates in 3 coordinated with Mo(iv) atoms through two oxygen atoms of -carboxy groups, leaving the -hydroxy group free. Furthermore, novel hexanuclear oxomolybdenum(v) malate Na6[(Mo2O4)3(mal)4]5H2O (4) was also isolated (H3mal = malic acid). Solid-state and solution 13C NMR resonances of carbon atoms in -alkoxy groups appeared in a high-field region (71.6, 77.4 ppm), indicating that -alkoxy groups were easy to protonate. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Dalton Transactions Royal Society of Chemistry

Comparison of hydroxycarboxylato imidazole molybdenum(iv) complexes and nitrogenase protein structures: indirect evidence for the protonation of homocitrato FeMo-cofactors

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Publisher
Royal Society of Chemistry
Copyright
This journal is © The Royal Society of Chemistry
ISSN
1477-9226
eISSN
1477-9234
DOI
10.1039/c8dt00278a
pmid
29786717
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Abstract

Glycolato and R,S-lactato imidazole molybdenum(iv) complexes [Mo3SO3(glyc)2(im)5]imH2O (1), Na2[Mo3SO3(R,S-lact)3(im)3]10H2O (2), and [Mo6O10(R,S-lact)2(im)10]16H2O (3) have been isolated and characterized (H2glyc = glycolic acid, H2lact = lactic acid, im = imidazole). -Alkoxy coordination with molybdenum [MoO-alkoxy 1.993(7)av ] in 1 and 2 showed obvious differences to their counterpart with -hydroxy coordination [MoIV3S4(PPh3)3(Hlact)2(lact)] [2.204(4)av ] 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, 1118. This was also true for the 36 reported structures of FeMo-cofactors in the RCSB protein data bank (MoOav 2.272 ), which can serve as indirect evidence for the protonation of homocitrate in FeMo-co. The COH-hydroxy bonds were longer than the short CO-alkoxy bonds. Trinuclear Mo3SO3 cores were stabilized by imidazoles and/or -hydroxycarboxylates, whereas only two glycolates were present in 1. -Hydroxycarboxylates in 1 and 2 acted as bidentate ligands of Mo(iv) atoms through -alkoxy and -carboxy groups, while the imidazoles coordinated monodentately with nitrogen atoms. The lactates in 3 coordinated with Mo(iv) atoms through two oxygen atoms of -carboxy groups, leaving the -hydroxy group free. Furthermore, novel hexanuclear oxomolybdenum(v) malate Na6[(Mo2O4)3(mal)4]5H2O (4) was also isolated (H3mal = malic acid). Solid-state and solution 13C NMR resonances of carbon atoms in -alkoxy groups appeared in a high-field region (71.6, 77.4 ppm), indicating that -alkoxy groups were easy to protonate.

Journal

Dalton Transactions – Royal Society of Chemistry

Published: May 22, 2018

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