title: Structural and Magnetic Diversity in Alkali-Metal Manganate Chemistry: Evaluating Donor and Alkali-Metal Effects in Co-complexation Processes.
abstract: By exploring co-complexation reactions between the manganese alkyl Mn(CH2SiMe3)2 and the heavier alkali-metal alkyls M(CH2SiMe3) (M=Na, K) in a benzene/hexane solvent mixture and in some cases adding Lewis donors (bidentate TMEDA, 1,4-dioxane, and 1,4-diazabicyclo[2,2,2] octane (DABCO)) has produced a new family of alkali-metal tris(alkyl) manganates. The influences that the alkali metal and the donor solvent impose on the structures and magnetic properties of these ates have been assessed by a combination of X-ray, SQUID magnetization measurements, and EPR spectroscopy. These studies uncover a diverse structural chemistry ranging from discrete monomers [(TMEDA)2 MMn(CH2SiMe3)3] (M=Na, 3; M=K, 4) to dimers [{KMn(CH2SiMe3)3 ⋅C6 H6}2] (2) and [{NaMn(CH2SiMe3)3}2 (dioxane)7] (5); and to more complex supramolecular networks [{NaMn(CH2SiMe3)3}∞] (1) and [{Na2Mn2 (CH2SiMe3)6 (DABCO)2}∞] (7)). Interestingly, the identity of the alkali metal exerts a significant effect in the reactions of 1 and 2 with 1,4-dioxane, as 1 produces coordination adduct 5, while 2 forms heteroleptic [{(dioxane)6K2Mn2 (CH2SiMe3)4(O(CH2)2OCH=CH2)2}∞] (6) containing two alkoxide-vinyl anions resulting from α-metalation and ring opening of dioxane. Compounds 6 and 7, containing two spin carriers, exhibit antiferromagnetic coupling of their S=5/2 moments with varying intensity depending on the nature of the exchange pathways.
authors.affiliation: WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, UK.
authors.forename: Marina
authors.initials: M
authors.lastname: Uzelac
authors.affiliation: Departament de Química Inorgànica, Universitat de Barcelona, Diagonal 645, 08028, Barcelona, Spain.
authors.forename: Ivana
authors.initials: I
authors.lastname: Borilovic
authors.affiliation: WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, UK.
authors.forename: Marco
authors.initials: M
authors.lastname: Amores
authors.affiliation: WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, UK.|Escuela Politécnica Nacional, Departamento De Física, Ladron de Guevera E11-253, Quito, 170517, Ecuador.
authors.forename: Thomas
authors.initials: T
authors.lastname: Cadenbach
authors.affiliation: WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, UK.
authors.forename: Alan R
authors.initials: AR
authors.lastname: Kennedy
authors.affiliation: Departament de Química Inorgànica, Universitat de Barcelona, Diagonal 645, 08028, Barcelona, Spain. guillem.aromi@qi.ub.es.
authors.forename: Guillem
authors.initials: G
authors.lastname: Aromí
authors.affiliation: WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, UK. eva.hevia@strath.ac.uk.
authors.forename: Eva
authors.initials: E
authors.lastname: Hevia
keywords: Lewis bases; alkali metals; cooperativity; magnetism; manganese