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Spectroscopic Properties, Electrochemistry, and Reactivity of Mo 0 , Mo I , and Mo II Complexes with the [Mo(bpa)(CO) 3 ] Unit [bpa = bis(2‐picolyl)amine] and Their Application for the Labelling of Peptides
Author(s) -
van Staveren Dave R.,
Bothe Eberhard,
Weyhermüller Thomas,
MetzlerNolte Nils
Publication year - 2002
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200206)2002:6<1518::aid-ejic1518>3.0.co;2-7
Subject(s) - chemistry , amine gas treating , dichloromethane , electrochemistry , acetonitrile , medicinal chemistry , solvent , organic chemistry , electrode
The synthesis of the complexes [Mo(bpa)(CO) 3 ] ( 1 ) and [Mo(Bz‐bpa)(CO) 3 ] ( 2 ) [bpa = bis(2‐picolyl)amine; Bz‐bpa = N ‐benzylbis(2‐picolyl)amine] is described. These compounds have been characterized by spectroscopic techniques including multinuclear NMR spectroscopy ( 1 H, 13 C, and 95 Mo), and also by X‐ray crystallography. Complexes 1 and 2 underwent reversible one‐electron oxidations in acetonitrile and dichloromethane with Bu 4 NPF 6 as supporting electrolyte to yield the 17‐electron organometallic compounds 1 + and 2 + . With Bu 4 NBr as supporting electrolyte in dichloromethane, on the other hand, 1 and 2 underwent electrochemically irreversible two‐electron oxidations, resulting in the formation of [Mo(bpa)(CO) 3 Br] + and [Mo(Bz‐bpa)(CO) 3 Br] + . Infrared spectra and electronic spectra of these oxidized species were recorded in spectro‐electrochemical studies. The electrochemical behaviour and the infrared spectroscopic data of 1 , 2 , and their oxidized derivatives are compared in detail with those of analogous tricarbonylmolybdenum complexes with the ligands 1,4,7‐triazacyclononane and hydridotris(pyrazolyl)borate. The complex [Mo(bpa)(CO)Br]Br 3 ( 3 ) could be prepared by oxidation of 1 with elemental bromine. Under aerobic aqueous conditions, 3 reacted further to yield the dinuclear diamagnetic Mo V complex [Mo 2 (bpa) 2 (O) 2 (μ‐O) 2 ](Br,PF 6 ) ( 4 ). The identity of 4 was confirmed by a single‐crystal X‐ray crystallographic study. Finally, the syntheses of two bioconjugates of [Mo(bpa)(CO) 3 ], in which bpa ligands are covalently linked to the N ‐termini of an amino acid (Phe‐OMe, 8a ) and of a dipeptide (Ala‐Phe‐OMe, 8b ), are described. These bioconjugates were comprehensively characterized (including elemental analysis, 1 H, 13 C, and 95 Mo NMR, IR, MS, and electrochemistry). All analytical data supported the proposed constitution and underscore the potential of the Mo(bpa)(CO) 3 group as a robust marker group in bioorganometallic chemistry. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)