title: Spin switching via targeted structural distortion.
abstract: The deliberate "stepwise" structural distortion of the [MnIII6O2(sao)6(O2CR)2L4] (S = 4, Ueff = 28 K) family of SMMs (where sao2- is the dianion of salicylaldoxime or 2-hydroxybenzaldeyhyde oxime and L = MeOH, EtOH) via the use of derivatized oxime ligands and bulky carboxylates leads to a family of single-molecule magnets with larger spin ground states and enhanced blocking temperatures. Replacing sao2- and HCO2- in the molecule [MnIII6O2(sao)6(O2CH)2(MeOH)4] (1), with Et-sao2- (Et-saoH2 = 2-hydroxypropiophenone oxime) and Me3CCO2- (pivalate), produces the complex [MnIII6O2(Et-sao)6(O2CCMe3)2(EtOH)5] (2) that displays an S = 7 ground state with Ueff = 30 K. Replacing Me3CCO2- with PhCO2- produces the complex [MnIII6O2(Et-sao)6(O2CPh)2(EtOH)4(H2O)2] (3) that displays an S = 12 ground state with Ueff = 53 K. The ligand substitution invokes a subtle structural distortion to the core of the molecule evidenced by an increased "twisting" of the oxime moiety (Mn-N-O-Mn) and a change in carboxylate ligation, which, in turn, invokes a dramatic change in the observed magnetic properties by switching weak antiferromagnetic exchange to weak ferromagnetic exchange.
authors: School of Chemistry, The University of Edinburgh, West Mains Road, Edinburgh, UK.
authors: Constantinos J
authors: CJ
authors: Milios
authors: Alina
authors: A
authors: Vinslava
authors: Wolfgang
authors: W
authors: Wernsdorfer
authors: Alessandro
authors: A
authors: Prescimone
authors: Peter A
authors: PA
authors: Wood
authors: Simon
authors: S
authors: Parsons
authors: Spyros P
authors: SP
authors: Perlepes
authors: George
authors: G
authors: Christou
authors: Euan K
authors: EK
authors: Brechin