title: Chiral transition metal clusters from two enantiomeric schiff base ligands. Synthesis, structures, CD spectra and magnetic properties.
abstract: Two enantiomeric Schiff base ligands R-/S-H2L in situ generated from the condensation of o-vanillin with R- or S-2-phenylglycinol were applied to assemble chiral multinuclear transition metal magnetic clusters for the first time. Four new enantiomerically pure chiral clusters, [NaMn4(3-O)(N3)1.75Br0.25(R-L)3(MeOH)2(H2O)2][NaMn4(mu3-O)(N3)2(R-L)3(MeOH)2(H2O)2]Br4 (1R), [NaMn4(mu3-O)(N3)1.75Br0.25(S-L)3(MeOH)2(H2O)2][NaMn4(mu3-O)(N3)2(S-L)3(MeOH)2(H2O)2]Br4 (1S), [Cu6(R-L)2(R-HL)2(N3)5(MeOH)]NO3.2MeOH.H2O (2R) and [Cu6(S-L)2(S-HL)2(N3)5(MeOH)]NO3.2MeOH.H2O (2S), have been synthesized and characterized by single crystal X-ray crystallography and CD spectroscopy. Three Mn(III) in the MnIIMnIII3 clusters of 1R and 1S are joined together through the 3-O bridge to form an oxo-centered Mn3O unit. Three L2- link four manganese atoms via the mu2-O,N,O-bridging manner into a MnIIMnIII3 cluster in a distorted tetrahedral geometry. Enantiomeric 2S and 2R are hexanuclear copper(II) clusters composed of a cubane-like Cu4L4 part with a dinuclear Cu2(N3)2 unit capped on one of the faces of the Cu4L4 cubane via the mu1,1-azide and phenolate bridges from the chiral ligands. Magnetic analysis reveals intracluster antiferromagnetic interaction between adjacent manganese ions in chiral oxo-centered MnIIMnIII3 magnetic clusters for 1R and 1S, and dominating antiferromagnetic over weak ferromagnetic interactions in Cu6 clusters in 2R and 2S.
authors.affiliation: Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou, 510275, China.
authors.forename: Lin-Lin
authors.initials: LL
authors.lastname: Fan
authors.forename: Fu-Sheng
authors.initials: FS
authors.lastname: Guo
authors.forename: Lei
authors.initials: L
authors.lastname: Yun
authors.forename: Zhuo-Jia
authors.initials: ZJ
authors.lastname: Lin
authors.forename: Radovan
authors.initials: R
authors.lastname: Herchel
authors.forename: Ji-Dong
authors.initials: JD
authors.lastname: Leng
authors.forename: Yong-Cong
authors.initials: YC
authors.lastname: Ou
authors.forename: Ming-Liang
authors.initials: ML
authors.lastname: Tong
mesh_terms: D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D008024:Ligands; D008280:Magnetics; D008958:Models, Molecular; D015394:Molecular Structure; D012545:Schiff Bases / Q000138:chemical synthesis* / Q000737:chemistry*; D013237:Stereoisomerism; D028561:Transition Elements / Q000737:chemistry*
chemical_list: D008024:Ligands; D012545:Schiff Bases; D028561:Transition Elements