Topological insights in polynuclear Ni/Na coordination clusters derived from a schiff base ligand (pdf)

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Topological insights in polynuclear Ni/Na coordination clusters derived from a schiff base ligand

Struct Chem (2016) 27:1703–1714 DOI 10.1007/s11224-016-0797-7 ORIGINAL RESEARCH Topological insights in polynuclear Ni/Na coordination clusters derived from a schiff base ligand Kieran Griffiths1 • Albert Escuer2 • George E. Kostakis1,3 Received: 30 April 2016 / Accepted: 9 June 2016 / Published online: 9 August 2016 Ó The Author(s) 2016. This article is published with open access at Springerlink.com Abstract This article presents the syntheses, crystal structures, topological features and magnetic properties of two NiII/NaI coordination clusters formulated [NiII3 Na(L1)3(HL1)(MeOH)2] (1) and [NiII6 Na(L1)5(CO3)(MeO) (MeOH)3(H2O)3]4(MeOH) 2(H2O) [2 4(MeOH) 2(H2O)] where H2L1 is the semi-rigid Schiff base ligand (E)-2(2-hydroxy-3-methoxybenzylideneamino)-phenol). Compound 1 possesses a rare NiII3 NaI cubane (3M4-1) topology, and compound 2 is the first example in polynuclear Ni/Na chemistry that exhibits a 2,3,4M7-1 topology. Keywords Coordination cluster Nickel Sodium Topology Schiff base Ferromagnetism Carbonate ion This work is dedicated to Prof Vladimir Ya. Shevcehnko on the occasion of his 75th birthday. Electronic supplementary material The online version of this article (doi:10.1007/s11224-016-0797-7) contains supplementary material, which is available to authorized users. & George E. Kostakis Albert Escuer 1 Department of Chemistry School of Life Sciences, University of Sussex, Brighton BN1 9QJ, UK 2 Departament de Quı́mica Inorgànica i Orgànica Secció de Quı́mica Inorgànica and Institut de Nanociència i Nanotecnologia (IN2UB), Universitat de Barcelona Martı́ i Franquès 1-11, 08028 Barcelona, Spain 3 Science and Educational Center of Physics of Noneqiliubrium Open Systems, Samara, National Research University, Moskovskoye Shosse 34, Samara 443086, Russia Introduction and review One of the most complex categories of coordination compounds are polynuclear coordination clusters (CCs) that incorporate multiple metal ions into a single molecular entity and are linked by bridging ligands [1]. These entities are of great interest for their aesthetically beautiful structures [2–4], unexpected transformations [5–7] and potential applications in magnetism [8–10], luminescence [11–15], catalysis [16–18], etc. Paramagnetic transition metal CCs are of intense interest and have attracted a vast amount of attention since the discovery that some CCs behave as single-molecule magnets (SMMs) [19–21]. The NiII (d8) ion has second-order orbital angular momentum, and zerofield splitting (ZFS) which can result in significant singleion anisotropy and potentially in molecules exhibiting interesting magnetic properties [22, 23]. The interest in polynuclear Ni(II) coordination chemistry was first captured when the first Ni(II)-based SMM, a Ni12 complex, was reported in 2001 by Cadiou et al. [24]. Ever since, there have been a number of homometallic polynuclear NiII CCs with high nuclearities including, Ni5 [7, 25], Ni6 [26], Ni7 [27, 28], Ni8 [29–32], Ni9 [33, 34], Ni11 [35], Ni12 [7], Ni13 [36], Ni14 [37], Ni20 [38], Ni21 [39], Ni24 [40] and Ni26 [41], and many of these display interesting magnetic properties including ferromagnetic, ferrimagnetic coupling, diamagnetism and SMM behaviour. Clusters of this size incorporate simple modified ligands with a wide variety of coordination modes for bridging, such as diethanolamine [42], Schiff base [43], carbide [44, 45] and carboxylate [46]. The introduction of bridging groups can increase the nuclearity of a CC. Carbonate anions offer a diverse range of bridging modes within cluster type molecules. A number of high-nuclearity CCs have been based on carbonate moieties [47, 48]. While 123 1704 Ni(II) CCs with bridging carbonate ligands are known, structural factors and magnetic exchange within these clusters greatly vary due to the large number of coordination modes of the CO32- anion [39, 49, 50]. Some interesting examples include, a Ni6 containing a carbonato bridge [51] and an Ni12 where four Ni4O4 units are templated around a central CO32- anion core [52]. On the other hand, the first reported mixed NiII/NaII CC was reported in 1976 by Jonas for potential small-molecule activation [53]. Since then, a number of NiII/NaII CCs have been reported, targeting for high-nuclearity clusters and interesting magnetic properties: Ni4Na2 [54], Ni4Na5 [55], Ni4Na3 [56], Ni4Na4 [57, 58] and others [59–62]. However, since 2007, NiII/NaI CCs with nuclearity over 10 have been reported far more frequently. The highest reported of these is a Ni18Na6 cluster [63] and the second Ni16Na4 [64], both synthesised by calix [4] arene-type ligands and the third is a Ni16Na2 cluster. In addition, two Ni12Na2 clusters were reported by Christou et al. [37, 65]. In all cases, similar anti-ferromagnetic behaviour was observed. The diprotic Schiff base ligand (E)-2-(2-hydroxy-3methoxybenzylideneamino)-phenol (H2L1, Scheme 1) initially reported in 1971 to capturing UO2 [66] can be synthesised in almost quantitative yields [67] and has two pockets that can coordinate to metal centres. Previously, this ligand has been involved in the synthesis of homometallic [68–71] and heterometallic CCs [72–75]. We recently employed this ligand in 3d/4f chemistry to synthesise a family of homogeneous efficient catalysts towards a domino reaction [76]. Interestingly, when H2L1 was employed in Ni(II) chemistry, a tetranuclear Ni4 CC exhibiting ferromagnetic interactions at low temperatures was isolated. [71] With the interest of introducing carbonate anions into a system, there are three key methods: direct addition of carbonate or bicarbonate [14], atmospheric fixation of carbon dioxide [77] and in situ decomposition of ligands [78]. Having all these in mind, in this article, we study the influence of the presence of Na cations and CO32- anions on the nuclearity of the given chemical system Ni(II)/H2L1 and we report two compounds formulated [NiII3 Na(L1)3(HL1)(MeOH)2] (1) and [NiII6 NaI(L1)5(CO3)(MeO)(MeOH)3 Struct Chem (2016) 27:1703–1714 (H2O)3]4(MeOH) 2(H2O) [2 4(MeOH) 2(H2O)]. Topological aspects and magnetic properties of these compounds are further discussed. Experimental Materials Chemicals (reagent grade) were purchased from SigmaAldrich and Alfa Aesar. All experiments were performed under aerobic conditions using materials and solvents as received. Instrumentation IR spectra of the samples were recorded over the range of 4000–650 cm-1 on a Perkin-Elmer Spectrum One FT-IR spectrometer fitted with a UATR polarization accessory. X-ray diffraction Crystallography Data for 1 and 24(MeOH) were collected at the National Crystallography Service, University of Southampton [79] using a Rigaku Saturn 724? area detector mounted at the window of an FR-E? rotating anode generator with a Mo anode (k = 0.71075 Å) under a flow of nitrogen gas at 150(2) K for 1 and 100(2) K for 24(MeOH). Both structures were determined using Olex2 [80], solved using eithe (...truncated)