Tert-Butylimido compounds of manganese-(VII), -(VI), -(V) and -(II); nitrido, amido, alkyl, zinc and aluminium compounds

Abstract

The interaction of Mn(NBut)3Cl with Li(NHBut) under prescribed conditions leads to the manganese(VI) dimer, [Mn(NBut)2(µ-NBut)]21 and lithium salts 2, 3 of the manganese(VII) nitrido anion [Mn(N)(NBut)3]2–, but the interaction with Li(NHC6H3Me2-2,6) gives the paramagnetic, tetrahedral, spiro manganese(II) complex [graphic omitted]H]24. The interaction of Mn(NBut)3Cl with methyllithium or dimethylzinc gives the dimeric methyl compound [MnMe(NBut)(µ-NBut)]25, while interaction with ZnR2(R = Et, CH2But, CH2CMe2Ph, CH2SiMe3 or CH2Ph) gives similar alkyls 6–10 respectively. The interaction of 1 with ZnR2 produces Mn2(NBut)2(µ-NBut)4ZnR (R = Me 11 or CH2But12), and with Al2Me6, Mn2(NBut)2(µ-NBut)4AIMe213. The interaction of [Li(dme)]2[Mn(NBut)4](dme = 1,2-dimethoxyethane) and Al2Me6 gives Mn[(µ-NBut)2AlMe2]214. The structures of compounds 1, 2, 3, 4, 7, 10 and 11 have been determined by X-ray crystallography. Compound 1 has been shown to be isostructural with its rhenium analogue, although twinning or disorder problems precluded accurate analysis. The nitrido compounds 2 and 3 have a common tetrahedral co-ordination sphere of manganese bonded to one nitride and three imido groups. The lithium cations are bonded to one nitride and three imido groups. The lithium cations are bonded to the imido nitrogen atoms, chloride ions and ether oxygen atoms. Compound 4 has a molecular structure which comprises a four-co-ordinate tetrahedral ‘spiro’ manganese atom chelated by two N(But)C(H)C6H3(Me)NH– ligands. The six-membered chelate ring formed is approximately planar and the spiro rings (one generated from the other by the two-fold axis through Mn) are almost perpendicular, with a dihedral angle of 91.5° at the MnII centre. The two formally single Mn–N bonds are slightly different at 2.036 and 2.135 A. The alkyl dimers 7 and 10 have closely analogous symmetrical structures, comprising two tetrahedral manganese atoms bridged by two imido groups and each bonded to one terminal imido and one alkyl ligand. With respect to the central Mn2N2 unit the two alkyls and the two imides adopt cis or Z arrangements. The geometry of the planar Mn2N2 unit in each structure has acute Mn–N–Mn (average 83.6°) and obtuse N–Mn–N (average 96.3°) angles consistent with the presence of direct Mn–Mn interaction, which formally has double bond character. Compound 11 has a molecular structure which contains a two-fold axis passing through the methyl and the Zn and Mn atoms. There is an unusual trigonal-planar ZnII atom bonded to a methyl group and two bridging imido groups; Mn(1), in oxidation state V, is bonded to four bridging imido ligands, and Mn(2), oxidation state VI, is bonded to two bridging and two terminal imido ligands.