Structural and Magnetic Insights into the Trinuclear Ferrocenophane and Unexpected Hydrido Inverse Crown Products of Alkali-Metal-Mediated Manganation(II) of Ferrocene

摘要

With the aim of introducing the diisopropylamide [NiPr2](-) ligand to alkali-metal-mediated manganation (AMMMn) chemistry, the temperature-dependent react ions of a 1:13 mixture of butylsodium, bis(trimethyl-silylmethyl)manganese(II), and diisopropylamine with ferrocene in hexane/toluene have been investigated. Performed at reflux temperature, the reaction affords the surprising. ferrocenefree, hydrido product [Na2Mn2 (mu-H)(2){N(iPr)(2)}(4)]center dot 2 toluene (1), the first Mn hydrido inverse crown complex. Repeating the reaction rationally, excluding ferrocene, produces 1 in in isolated crystalline yield of 62%. At lower temperatures, the same bimetallic amide mixture leads to the manganation of ferrocene to generate the first trimanganese, trinuclear ferrocenophane, [{Fe(C5H4)(2)}(3){Mn3Na2(NiPr2)(2) (HNiPr2)(2)}] (2) in an isolated crystalline yield of 81%. Both 1and 2 have been characterised by X-ray crystallo-graphic studies. The magnetic properties of paramagnetic 1 and 2 have also been examined by variable-temperature magnetisation measurements on powdered samples. For 1, the room-temperature value for chi T is 3.45cm(3)K mol(-1), and on lowering the temperature a strong antiferromagnetic coupling between the two Mn ions is observed. For 2, the room-temperature value for chi T is 4.06 cm(3) Kmol(-1), which is significantly lower than the expected value for three isolated paramagnetic Mn-II ions.