Dalton Transactions Dynamic Article Links Cite this: Dalton Trans., 2012, 41, 11402 www.rsc.org/dalton PAPER Ln III 2 Mn III 2 heterobimetallic “butterfly” complexes displaying antiferromagnetic coupling (Ln = Eu, Gd, Tb, Er)† Anthony S. R. Chesman,‡ a David R. Turner, a Kevin J. Berry, b Nicholas F. Chilton, a Boujemaa Moubaraki, a Keith S. Murray, a Glen B. Deacon a and Stuart R. Batten* a Received 27th May 2012, Accepted 4th July 2012 DOI: 10.1039/c2dt31144e The isostructural heterometallic complexes [Ln III 2 Mn III 2 O 2 (ccnm) 6 (dcnm) 2 (H 2 O) 2 ] (Ln = Eu (1Eu), Gd (1Gd), Tb (1Tb), Er (1Er); ccnm = carbamoylcyanonitrosomethanide; dcnm = dicyanonitrosomethanide) have been synthesised and structurally characterised. The in situ transition metal promoted nucleophilic addition of water to dcnm, forming the derivative ligand ccnm, plays an essential role in cluster formation. The central [Ln III 2 Mn III 2 (O) 2 ] moiety has a “butterfly” topology. The coordinated aqua ligands and the NH 2 group of the ccnm ligands facilitate the formation of a range of hydrogen bonds with the lattice solvent and neighbouring clusters. Magnetic measurements generally reveal weak intracluster antiferromagnetic coupling, except for the large J MnMn value in 1Gd. There is some evidence for single molecule magnetic (SMM) behaviour in 1Er. Comparisons of the magnetic properties are made with other recently reported butterfly-type {Ln III x M III 4−x (d-block)} clusters, x = 1, 2; M = Mn, Fe. Introduction The examination of 3d/4f heterometallic complexes has generated much interest due to their magnetic properties, such as ferro- magnetic coupling between transition metal and lanthanoid ions. 1 In addition, a recent focus in magnetochemistry has resulted in the synthesis of single molecule magnets (SMMs), 2 molecules that show magnetic hysteresis due to a slow magneti- zation reversal resulting from a high energy barrier. Heterometal- lic 3d/4f clusters have demonstrated promise in this area as the high spin and anisotropy inherent in some lanthanoids, such as dysprosium, are highly beneficial in giving rise to SMM proper- ties in complexes. 3 “Butterfly” complexes derive their name from the configur- ation of their tetranuclear core, which contains two oxygen atoms with μ 3 -η 1 :η 1 :η 1 connectivity. 4 These μ 3 -oxygens are usually O 2− or OH − , but may also be alkoxide oxygen atoms, with examples of carbide 4j and sulfide 4k bridges also reported. These complexes may be homometallic, potentially with differ- ing oxidation states between the metal centres, 4h,i or heterometallic with differing metal types located on the “wings” and “body” of the complex (Fig. 1). 4k Additional bridging func- tional groups may be present on the periphery of the complex. A butterfly complex with a [V 4 O 2 ] core has been reported to act as an SMM. 4g The butterfly structure is well documented in tran- sition metal chemistry but incorporation of lanthanoids into the motif to form heterobimetallic complexes has proven elusive, with few examples known. 5 An early Cu/Gd butterfly complex indicated ferromagnetic coupling between the transition metal and lanthanoid atoms, 5a while Christou et al. have synthesised, among others, [Fe 2 Ho 2 (OH) 2 (teaH) 2 (O 2 CPh) 4 (NO 3 ) 2 ] and [Fe 2 Dy 2 (OH) 2 - (teaH) 2 (O 2 CPh) 6 ] (teaH 3 = triethanolamine), which were the first reported 4f/Fe single molecule magnets. 5c Heterobimetallic butterfly complexes may also incorporate 4d metals, as evi- denced by the [Fe 2 Y 2 (pdmH) 6 Cl 4 ]Cl 2 ( pdmH 2 = pyridine-2,6- dimethanol) 5c and [Ce 2 Nb 2 O 2 (pin) 4 (OPr i ) 6 ] (pinH 2 = pinacol) complexes. 5d The previously reported complexes usually contain the transition metal in the “body” of the butterfly, with the Fig. 1 “Butterfly” motif present in tetranuclear complexes; M atoms are on the “wing” position while M′ atoms are on the “body” of the butterfly. † Electronic supplementary information (ESI) available: Figures detail- ing the hydrogen bonding between the clusters (Fig. S1, S2, S3, S4), bond valence sum calculations of complexes 1Gd, 1Tb and 1Er. CCDC 884900–884902. For ESI and crystallographic data in CIF or other elec- tronic format see DOI: 10.1039/c2dt31144e ‡ Current address: CSIRO Materials Science and Engineering, Ian Wark Laboratories, Bayview Ave, Clayton, VIC 3169, Australia. a School of Chemistry, Monash University, Clayton, VIC 3800, Australia. E-mail: stuart.batten@monash.edu; Fax: +61 (0)3 9905 4597; Tel: +61 (0)3 9905 4606 b 23 Seabreeze Street, Balnarring, VIC 3926, Australia 11402 | Dalton Trans., 2012, 41, 11402–11412 This journal is © The Royal Society of Chemistry 2012 Downloaded by Monash University on 17 September 2012 Published on 04 July 2012 on http://pubs.rsc.org | doi:10.1039/C2DT31144E View Online / Journal Homepage / Table of Contents for this issue