www.elsevier.nl/locate/jorganchem Journal of Organometallic Chemistry 591 (1999) 36 – 44 Imido complexes of manganese Andreas A. Danopoulos a, *, Jennifer C. Green b , Michael B. Hursthouse a a Department of Chemistry, Uniersity of Southampton, Highfield, Southampton SO17 1BJ, UK b Inorganic Chemistry Laboratory, Uniersity of Oxford, South Parks Road, Oxford OX13QR, UK Received 17 June 1999; accepted 22 July 1999 Abstract The developments in the chemistry of manganese by the use of the imido group (RN 2 - ) are reviewed with emphasis on our own work in the area. The increased kinetic stability of the ‘Mn(N t Bu) 3 ’ fragment enabled the isolation and study of a good number and variety of derivatives in oxidation states V – VII, bearing, amongst others, MnC, MnN, MnS and MnO bonds. © 1999 Elsevier Science S.A. All rights reserved. Keywords: Manganese; Imido; Alkyl; Amide; Thiolate 1. Introduction Following the discovery of the first imido complex OsO 3 (N t Bu) by Clifford and Kobayashi [1], this area of chemistry has witnessed a tremendous growth, espe- cially in the last decade. The two main directions of research, i.e. (i) the use of the imido ligand as a stabilising or ancillary ‘spectator’ in organometallic chemistry and catalysis; and (ii) the study of selective transformations involving the imido ligand and a vari- ety of substrates, were greatly facilitated by the refine- ment of our understanding of the metal – nitrogen multiple bonding. Today, imido complexes are known for the majority of the transition metals, although, those with first row and late transition metals have been more difficult to synthesise but show fascinating reactivity. Recent developments have been described in a mono- graph [2] and a review [3]. Part of our contribution to the imido chemistry is related to the discovery of a new family of high oxidation state manganese compounds. A substantial part of this research was developed after the appearance of Wigley’s review [3] and therefore a full account of it is now timely. Recent work in the same area by other researchers will also be mentioned. 2. Monomeric d 0 Mn(VII) imido complexes The history of MnO 4 n - (n =1, 2) is long and their chemistry rather well established [4]. Mn 2 O 7 and the oxohalides MnO 3 X (X =F, Cl) have also been known for a while [4,5], but have been prepared in pure form only relatively recently [5c], mainly because of the difficulties associated with their handling and their ther- modynamic instability. All the aforementioned oxo- compounds are powerful and rather unselective oxidants, especially towards organic substrates. These reasons, in combination with the high degree of aggre- gation and, consequently, inertness of oxo-manganates in intermediate oxidation states (III – V) hampered at- tempts to synthesise imido analogues of the known oxo complexes. Following well-established synthetic meth- ods [1,2], e.g. treating oxo-compounds with amines, silylamines, isocyanates and phosphinimines, results in uncontrolled oxidations and intractable mixtures. How- ever, the existence of the transient manganese imido intermediates was strongly implicated in the work by Groves and Takahashi [6] who detected the paramag- netic TMPMn(NCOCF 3 )(OCOCF 3 ) (TMP =5, 10, 15, 20-tetramesitylporphyrinato-) after reacting TMP- Mn(N) with (CF 3 CO) 2 O. Later, Mahy et al. [7] postu- lated manganese imido intermediates in the aziridina- tion of alkenes by tosylimino – iodobenzene (PhI =NTs, Ts =tosyl) catalysed by Mn(TTP)Cl (TTP =te- traphenylporphyrinato). This transformation has been further investigated recently [8]. * Corresponding author. Fax: +44-1703-593-781. E-mail address: ad1@soton.ac.uk (A.A. Danopoulos) 0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved. PII:S0022-328X(99)00448-9