title: Hierarchical Assembly of a {Mn(II)15Mn(III)4} Brucite Disc: Step-by-Step Formation and Ferrimagnetism.
abstract: In search of functional molecular materials and the study of their formation mechanism, we report the elucidation of a hierarchical step-by-step formation from monomer (Mn) to heptamer (Mn7) to nonadecamer (Mn19) satisfying the relation 1 + Σn6n, where n is the ring number of the Brucite structure using high-resolution electrospray ionization mass spectrometry (HRESI-MS). Three intermediate clusters, Mn10, Mn12, and Mn14, were identified. Furthermore, the Mn19 disc remains intact when dissolved in acetonitrile with a well-resolved general formula of [Mn19(L)x(OH)y(N3)36-x-y](2+) (x = 18, 17, 16; y = 8, 7, 6; HL = 1-(hydroxymethyl)-3,5-dimethylpyrazole) indicating progressive exchange of N3(-) for OH(-). The high symmetry (R-3) Mn19 crystal structure consists of a well-ordered discotic motif where the peripheral organic ligands form a double calix housing the anions and solvent molecules. From the formula and valence bond sums, the charge state is mixed-valent, [Mn(II)15Mn(III)4]. Its magnetic properties and electrochemistry have been studied. It behaves as a ferrimagnet below 40 K and has a coercive field of 2.7 kOe at 1.8 K, which can be possible by either weak exchange between clusters through the anions and solvents or through dipolar interaction through space as confirmed by the lack of ordering in frozen CH3CN. The moment of nearly 50 NμB suggests Mn(II)-Mn(II) and Mn(III)-Mn(III) are ferromagnetically coupled while Mn(II)-Mn(III) is antiferromagnetic which is likely if the Mn(III) are centrally placed in the cluster. This compound displays the rare occurrence of magnetic ordering from nonconnected high-spin molecules.
authors.affiliation: Key Lab of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University , Jinan 250100, P. R. China.
authors.forename: Yong-Kai
authors.initials: YK
authors.lastname: Deng
authors.affiliation: State Key Laboratory for Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, People's Republic of China.
authors.forename: Hai-Feng
authors.initials: HF
authors.lastname: Su
authors.affiliation: Key Lab of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University , Jinan 250100, P. R. China.
authors.forename: Jia-Heng
authors.initials: JH
authors.lastname: Xu
authors.affiliation: Key Lab of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University , Jinan 250100, P. R. China.
authors.forename: Wen-Guang
authors.initials: WG
authors.lastname: Wang
authors.affiliation: Institut de Chimie de Strasbourg, Université de Strasbourg, CNRS-UMR 7177 , 4 rue Blaise Pascal, 67008 Cedex Strasbourg, France.
authors.forename: Mohamedally
authors.initials: M
authors.lastname: Kurmoo
authors.affiliation: State Key Laboratory for Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, People's Republic of China.
authors.forename: Shui-Chao
authors.initials: SC
authors.lastname: Lin
authors.affiliation: State Key Laboratory for Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, People's Republic of China.
authors.forename: Yuan-Zhi
authors.initials: YZ
authors.lastname: Tan
authors.affiliation: Key Lab of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University , Jinan 250100, P. R. China.
authors.forename: Jiong
authors.initials: J
authors.lastname: Jia
authors.affiliation: Key Lab of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University , Jinan 250100, P. R. China.|State Key Laboratory for Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, People's Republic of China.
authors.forename: Di
authors.initials: D
authors.lastname: Sun
authors.affiliation: State Key Laboratory for Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, People's Republic of China.
authors.forename: Lan-Sun
authors.initials: LS
authors.lastname: Zheng