Structural and Magnetic Diversity in Alkali‐Metal Manganate Chemistry: Evaluating Donor and Alkali‐Metal Effects in Co‐complexation Processes

By exploring co‐complexation reactions between the manganese alkyl Mn(CH 2 SiMe 3 ) 2 and the heavier alkali‐metal alkyls M(CH 2 SiMe 3 ) (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(CH 2 SiMe 3 ) 3 ] (M=Na, 3 ; M=K, 4 ) to dimers [{KMn(CH 2 SiMe 3 ) 3 ⋅C 6 H 6 } 2 ] ( 2 ) and [{NaMn(CH 2 SiMe 3 ) 3 } 2 (dioxane) 7 ] ( 5 ); and to more complex supramolecular networks [{NaMn(CH 2 SiMe 3 ) 3 } ∞ ] ( 1 ) and [{Na 2 Mn 2 (CH 2 SiMe 3 ) 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) 6 K 2 Mn 2 (CH 2 SiMe 3 ) 4 (O(CH 2 ) 2 OCH=CH 2 ) 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.