Joan Ribas

Two new end-to-end (EE) cyanate bridged 1D coordination polymers of Ni^II are isolated which contain linear (180°) Ni–N–C and Ni–O–C angles in Ni–NCO–Ni bridges and show ferromagnetic (F) coupling in agreement with the reported theoretical model for linear EE bridges.

The coordination polymer, {[Co(tart)(phen)]·6H₂O}_n (1) (tart, tartrate dianion; phen, 1,10‐phenanthroline) has been synthesized and characterized by single‐crystal X‐ray structure determination, magnetic measurement and thermal analysis. The structural analyses reveal two adjacent parallel 1D–[Co(phen)‐tart‐Co(phen)]– coordination polymers zipped through π‐π interactions. The lattice water molecules, forming a 1D water cluster, function as glue to form a 3D supramolecular network through an extended hydrogen bonding. A comparison highlighting the structural differences with the corresponding 2,2′‐bipyridine (bpy) derivative, {[Co(tart)(bpy)]·5H₂O}_n (2) containing a less amount of lattice water molecules is discussed. The variable‐temperature magnetic study of 1 has been carried out and interpretation of the already reported complex 2 has been re‐visited: both polymers 1 and 2 show weak antiferromagnetic interaction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Three new carboxylato‐bridged polymeric networks of Mn^II having molecular formula [Mn(ox)(dpyo)]_n (1), {[Mn₂(mal)₂(bpee)(H₂O)₂]·0.5(bpee)·0.5(CH₃OH)}_n (2) and {[Mn₃(btc)₂(2,2′‐bipy)₂(H₂O)₆]·4H₂O}_n (3) [dpyo, 4,4′‐bipyridine N,N′‐dioxide; bpee, trans‐1,2 bis(4‐pyridyl)ethylene; 2,2′‐bipy, 2,2′‐bipyridine; ox = oxalate dianion; mal = malonate dianion; btc = 1,3,5‐benzenetricarboxylate trianion] have been synthesized and characterized by single‐crystal X‐ray diffraction studies and low temperature magnetic measurements. Structure determination of complex 1 reveals a covalent bonded 2D network containing bischelating oxalate and bridging dpyo; complex 2 is a covalent bonded 3D polymeric architecture, formed by bridging malonate and bpee ligands, resulting in an open framework with channels filled by uncoordinated disordered bpee and methanol molecules. Whereas complex 3, comprising btc anions bound to three metal centers, is a 1D chain which further extends its dimensionality to 3D via ‐ and H‐bonding interactions. Low temperature magnetic measurements reveal the existence of weak antiferromagnetic interaction in all these complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Three new polymeric squarato-bridged manganese complexes {[Mn(H₂O)₂(bpe)(sq)]·bpe·H₂O}_n (1), [Mn₂(H₂O)₄(phen)₂(sq)₂]_n (2) and [Mn₂(H₂O)₂(phen)₄(sq)]·(sq)·8(H₂O) (3) [bpe, 1,2-bis(4-pyridyl)ethane; phen, 1,10-phenanthroline; sq, squarate dianion] have been synthesized and characterized by single crystal X-ray diffraction analysis and variable temperature magnetic studies. Complex 1 is a 2D rectangular grid-like structure, achieved through flexible bpe bridging ligands and squarate dianions. On the other hand the use of chelating phen instead of bpe gives rise to a 1D polymeric chain in complex 2 and to a dinuclear entity in 3. In all the three complexes weak interactions play a vital role in stabilizing the solid-state structure. Variable temperature (2–300 K) magnetic studies indicate weak antiferromagnetic coupling between the metal centres in all the complexes.

Three new metal–organic hybrid polymeric networks of Co^II and Mn^II with the molecular formulae [Co(bpp)(tp)(H₂O)₂] (1), [Mn(bpds)(tp)(H₂O)₂]·(bpds) (2), and [Mn(4,4′‐bipy)(H₂O)₄]·(tp) (3) (bpp = 4,4′‐trimethylenedipyridine; bpds = 4,4′‐bipyridyl disulfide; 4,4′‐bipy = 4,4′‐dipyridyl; tp = terephthalate) have been synthesized and characterized by single‐crystal X‐ray diffraction studies, low temperature (300–2 K) magnetic measurements, and thermal behaviors. The structure determination of complexes 1 and 2 reveals a parallel interpenetrated structure of 2D layers with (4,4) topology, with metal ions at the nodes connected through tp and N,N‐donor coligands. The octahedral N₂O₄ chromophore surrounding the metal ion results from trans located tp oxygens, two water molecules, and two nitrogen donors of the co‐ligands in the cis position. The presence of uncoordinated bpds between the interpenetrated layers leads to the formation of a wafer‐like structure for 2. In complex 3, however, manganese(II) ions bridged by 4,4′‐bipy and coordinated by four water molecules give rise to a 1D polymeric chain. The adjoining chains encapsulate terephthalate anions (tp) to give a 3D structure through H‐bonding. Low‐temperature magnetic data indicate weak antiferromagnetic coupling in complexes 1 and 2. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Two polymeric azido bridged complexes [Ni₂L₂(N₃)₃]_n(ClO₄)_n (1) and [Cu(bpds)₂(N₃)]_n(ClO₄)_n(H₂O)_2.5n (2) [L = Schiff base, obtained from the condensation of pyridine‐2‐aldehyde with N,N,2,2‐tetramethyl‐1,3‐propanediamine; bpds = 4,4'‐bipyridyl disulfide] have been synthesized and their crystal structures have been determined. Complex 1, C₂₆H₄₂ClN₁₅Ni₂O₄, crystallizes in a triclinic system, space group P$\tilde {1}$ with a = 8.089(13), b = 9.392(14), c = 12.267(18) Å, α = 107.28(1), β = 95.95(1), γ = 96.92(1)° and Z = 2; complex 2, C₂₀H₂₁ClCuN₇O_6.5S₄, crystallizes in an orthorhombic system, space group Pnna with a = 10.839(14), b = 13.208(17), c = 19.75(2) Å and Z = 4. The crystal structure of 1 consists of 1D polymers of nickel(L) units, alternatively connected by single and double bridging μ‐(1,3‐N₃) ligand with isolated perchlorate anions. Variable temperature magnetic susceptibility data of the complex have been measured and the fitting of magnetic data was carried out applying the Borrás‐Almenar formula for such types of alternating one‐dimensional S = 1 systems, based on the Hamiltonian H = –JΣ(S_2iS_2i–1 + αS_2iS_2i+1). The best‐fit parameters obtained are J =–106.7 ± 2 cm^–1; α = 0.82 ± 0.02; g = 2.21 ± 0.02. Complex 2 is a 2D network of 4,4 topology with the nodes occupied by the Cu^II ions, and the edges formed by single azide and double bpds connectors. The perchlorate anions are located between pairs of bpds. The magnetic data have been fitted considering the complex as a pseudo‐one‐dimensional system, with all copper(II) atoms linked by μ(1,3‐azido) bridging ligands at axial positions (long Cu···N₃ distances) since the coupling through long bpds is almost nil. The best‐fit parameters obtained with this model are J = –1.21 ± 0.2 cm^–1, g = 2.14 ± 0.02. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)