TY - JOUR
T1 - Structural and Magnetic Diversity in Alkali-Metal Manganate Chemistry
T2 - Evaluating Donor and Alkali-Metal Effects in Co-complexation Processes
AU - Uzelac, Marina
AU - Borilovic, Ivana
AU - Amores, Marco
AU - Cadenbach, Thomas
AU - Kennedy, Alan R.
AU - Aromí, Guillem
AU - Hevia, Eva
N1 - Funding Information:
We thank the EPSRC, the Royal Society, and the European Research Council (ERC) for their generous sponsorship of this research. We also thank Professor Robert E. Mulvey for his insightful comments and Alexander Clunie for his assistance in the CHN analysis of highly air- A nd moisture-sensitive compounds.
PY - 2016/3/24
Y1 - 2016/3/24
N2 - 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)2MMn(CH2SiMe3)3] (M=Na, 3; M=K, 4) to dimers [{KMn(CH2SiMe3)3C6H6}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.
AB - 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)2MMn(CH2SiMe3)3] (M=Na, 3; M=K, 4) to dimers [{KMn(CH2SiMe3)3C6H6}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.
KW - alkali metals
KW - cooperativity
KW - Lewis bases
KW - magnetism
KW - manganese
UR - http://www.scopus.com/inward/record.url?scp=84959386277&partnerID=8YFLogxK
U2 - 10.1002/chem.201504956
DO - 10.1002/chem.201504956
M3 - Article
AN - SCOPUS:84959386277
SN - 0947-6539
VL - 22
SP - 4843
EP - 4854
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
IS - 14
ER -