Dalton Transactions Dynamic Article Links Cite this: Dalton Trans., 2011, 40, 12358 www.rsc.org/dalton PAPER Complexes of a hexa-nitrile dianion with neutral, chelating co-ligands: Self-assembly, structure and magnetism† Anna M. Kutasi, David R. Turner, Boujemaa Moubaraki, Stuart R. Batten* and Keith S. Murray* Received 21st July 2011, Accepted 15th September 2011 DOI: 10.1039/c1dt11369k Several new first-row transition-metal complexes have been synthesised by combining the polynitrile dianion HCTMCP 2- (hexacyanotrimethylenecyclopropandiide) with neutral, chelating co-ligands; 2,2¢-bipyridine, 1,10-phenanthroline and 3-(2-pyridyl)pyrazole. The products cover a remarkable range of species including mononuclear complexes, dimers, charge-separated species and coordination polymers. Complexes containing 2,2¢-bipyridine take the form [Mn(2,2¢-bipy) 2 (HCTMCP)] 2 ·2MeOH (1) or [M(2,2¢-bipy) 3 ](HCTMCP) (2Fe and 2Co) which are dimeric and charge-separated products, respectively. The products obtained using 1,10-phenanthroline were the discrete complex [Co(HCTMCP)(1,10-phen) 2 (H 2 O)]·H 2 O·MeCN (3) and the 1D coordination polymer [Mn(HCTMCP)(1,10-phen)(H 2 O)(MeOH)] (4). Complexes using the 3-(2-pyridyl)pyrazole co-ligand (pypzH) form similar 1D complexes to 4, namely [Mn(pypzH)(HCTMCP)(MeOH)(H 2 O)] (5) and [M(pypzH)(HCTMCP)(MeOH) 2 ](6Co and 6Fe), albeit with different hydrogen-bonding motifs between the chains. The polymeric HCTMCP complexes show weak to zero antiferromagnetic coupling between metal centres and thus no long-range ordering. Introduction Coordination polymers that contain bridging polynitrile ligands are of interest for their potential to display magnetic communica- tion between adjacent metal atoms. 1–9 Since the characterisation of Prussian Blue, 2–5 and the subsequent studies of analogous systems, 4,5 there has been much research concerning materials in which magnetic ordering occurs at high temperatures. 6–9 The non-linear, polynitrile species [N(CN) 2 ] - (dicyanamide, dca) and [C(CN) 3 ] - (tricyanomethanide, tcm) have been known for a number of decades, 10–12 although it is relatively recently that they have been incorporated into materials that display long-range magnetic ordering. 13–20 Such compounds have been observed to show both ferromagnetic ordering and spin-canted antiferromagnetic behaviour. Larger polynitrile ligands, such as 2- dicyanomethylene-1,1,3,3-tetracyanopropanediide (TCPD), 2,2- dicyano-1-ethoxyethenolate (DCNE) and 1,1,2,4,5,5-hexacyano- 3-aza-penta-1,4-dienide (HCAZPD) have also been used in polymeric materials, typically displaying weak antiferromagnetic behaviour. 21–25 While the abovementioned polynitrile ligands are diamagnetic, and thus magnetic exchange coupling arises from School of Chemistry, Monash University, Clayton, Vic. 3800, Aus- tralia. E-mail: stuart.batten@monash.edu, keith.murray@monash.edu; Fax: +61(0)3 9905 4597; Tel: +61(0)3 9905 4512 †Electronic supplementary information (ESI) available: CIF containing data for complexes 1–6 and magnetic plots for all compounds except 2Fe. CCDC reference numbers 836013–836020. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c1dt11369k spins on the metal ions, the paramagnetic (S = 1 2 ), radical ligands TCNQ -∑ (tetracyanoquinodimethanide) and TCNE -∑ (tetracya- noethyleneide), and their substituted analogues, continue to receive great attention, not only in donor–acceptor systems, but also for their molecular magnetic-ordering properties, with recent studies of m 4 -cyano bridging in V II , Mn II , Ru II 2 and lanthanide materials being prominent and leading to network structures in some cases. 26–30 Hexacyanotrimethylenecyclopropandiide (HCTMCP 2- ), the ligand of interest in the present study, is a hexa-nitrile dianion that is also known in its monoanionic radical form, HCTMCP -∑ . 31–38 The planar anion possesses six nitrile arms that are arranged around a radialene-type C 3 core (Fig. 1a). The anion has been successfully employed in a number of donor–acceptor salts, such as [(h 6 -C 6 Me 3 H 3 ) 2 M][HCTMCP] or [(h 6 -C 6 Me 6 ) 2 M][HCTMCP] (M = Fe, Ru) in which charge-transfer (CT) occurs between stacks of alternating cations/anions. 31 The radical monoanion has also been reported in CT compounds with separate anion and cation stacks 32 and in electron-transfer salts. 33 We recently reported the first coordination polymers to contain HCTMCP 2- as a bridging ligand, with three different coordination geometries observed; (A) m 1,4 (B) m 1,2,4 and (C) m 1,3,5 (Fig. 1(top)). 38 In these coordination polymers the anions were observed to engage in coordination bonding, hydrogen bonding, and extended p stacking interactions. Thus it was of interest to further explore the self-assembly behaviour of this large, planar anion which has a core containing an extensively delocalised p system and peripheral functional groups capable of participating in coordinative and hydrogen bonding. 12358 | Dalton Trans., 2011, 40, 12358–12367 This journal is © The Royal Society of Chemistry 2011