DMF Oxygen Research Articles

2.2]Paracyclophane Derivatives as Building Blocks for Coordination Polymers.

Several new di- and tetracarboxylic [2.2]paracyclophane derivatives were obtained via Suzuki coupling between the appropriately brominated [2.2]paracyclophanes and 4-(methoxycarbonyl)phenylboronic acid. The reaction of one of these products, namely pp-bis(4-carboxyphenyl)[2.2]paracylophane (12), with zinc nitrate afforded a 2D coordination polymer comprising zinc-carboxylate paddlewheel clusters linked together by cyclophane cores. The zinc center is five-coordinated in a square-pyramidal geometry, with a DMF oxygen atom at the apex and four carboxylate oxygen atoms in the base.

Crystallographic elucidation of an aluminium-bound amido Schiff base chemosensor: a selective turn-on fluorescent chemosensor for Al3+ ions.

We have synthesized a biphenyl-derived two arm-containing amido Schiff base, bis((2-hydroxynaphthalen-1-yl) methylene)-[1,1'-biphenyl]-2,2'-dicarbohydrazide (sensor 1), having hard donors to facilitate chelation with hard metal centers. The crystal structure of sensor 1 reveals that it crystallizes in the monoclinic system with the space group I2/a and shows several types of intra/inter-molecular H-bond interactions, which stabilized the crystal lattice. The sensing property of sensor 1 towards different metal ions has been demonstrated using different analytical techniques. In fact, sensor 1 shows high fluorescence selectivity and sensitivity towards Al3+ ions in aqueous DMF media. Importantly, we have reported the first structurally characterized six-coordinate dinuclear Al3+ complex ([Na(Al2L2)·2H2O·4DMF], complex 1 (where ligand, L = sensor 1). Complex 1 crystallizes in the space group P1̄. X-ray single crystal diffraction studies for complex 1 reveal that each Al3+ ion is hexa-coordinated by four oxygen and two nitrogen atoms from each arm of the two ligands. The sodium ion has penta-coordination in a highly distorted trigonal bipyramidal geometry, surrounded by two μ-bridging naphtholate oxygen atoms and three solvent DMF oxygen atoms. Upon addition of Na2EDTA to complex 1, no spectral change or naked-eye colour change was observed. Furthermore, "test kits" coated with sensor 1 showed successful selective detection of Al3+ ions under UV light.

A red-emitting Mn(II)-based coordination polymer build on 1,2,4,5-tetrakis(diphenylphosphinyl)benzene

The reaction of Mn(ClO4)2·6H2O with 1,2,4,5-tetrakis(diphenylphosphinyl)benzene (L) in DMF affords one-dimensional coordination polymer (CP), [MnL(DMF)2](ClO4)2·DMF, in 87% yield. The cationic chains of the CP are assembled from alternating Mn(II) ions and ligand molecules; each metal ion has a octahedral MnO6 environment composed of four oxygen atoms from two adjacent ligands and two DMF oxygen atoms. At the temperatures below 200 K, this CP demonstrates a red phosphorescence with λemmax~660 nm and lifetimes of 1.5–4.5 ms. The EPR study reveals the high-spin state of the Mn(II) ions and the absence of exchange interactions between them.

Chalcogen bonding interactions in organic selenocyanates: from cooperativity to chelation

Organic selenocyanates form recurrent chain-like motifs ⋯Se(R)–CN⋯Se(R)–CN⋯ through short and linear chalcogen bonding Se⋯NC interactions. A chelating motif is also observed in a DMF solvate with two neighboring CH2–SeCN groups linked to the DMF oxygen atom.

Three‐Dimensional Co‐ and Mn‐MOFs Containing a C2h‐Symmetric Terphenyl‐3,3′‐dicarboxylate Linker and Their Magnetic Properties

We report herein two new isostructural, three‐dimensional (3D) MOFs with the general formula [M(3,3′‐tpdc)(dmf)] [M = CoII (I), MnII (II)] resulting from the assembly of a metal ion and the C2h‐symmetric ditopic bridging ligand terphenyl‐3,3′‐dicarboxylate (3,3′‐tpdc). Both isostructural MOFs crystallize in the monoclinic space group C2/c. The metal ion is coordinated by four Ocarboxylate (η1:η1:µ2) and two µ2‐Odmf atoms in a distorted octahedral geometry. The metal centers are interconnected through bridging 3,3′‐tpdc and dmf ligands to form a 1D chain. The resulting 1D metal chains are further interconnected by 3,3′‐tpdc ligands to form 3D frameworks without porosity. The thermolabile dmf bridging ligands were easily removed by heating at 180 °C under vacuum for 5 h. The activated MOFs I and II exhibited very low gas uptake of N2, CO2, and H2 after removal of the dmf bridging ligands. The encapsulation of iodine guest molecules by the activated I and II was also investigated. The crystal structure of iodine‐encapsulated II was also elucidated. The coordination environment of the MnII atom in II changed as a result of the loss of dmf bridging ligands. The as‐prepared MOFs I and II exhibit weak antiferromagnetic interactions in their 1D metal chains; these magnetic interactions should mainly occur between the metal ions bridged by the short carboxylate‐based ligand and dmf oxygen atoms. Thermal removal of the bridging dmf molecules led to a change in the Mn···Mn distances in the 1D chains of II that also affected its magnetic properties.

Promoting the Hydrosilylation of Benzaldehyde by Using a Dicationic Antimony-Based Lewis Acid: Evidence for the Double Electrophilic Activation of the Carbonyl Substrate.

The concomitant activation of carbonyl substrates by two Lewis acids has been investigated by using [1,2-(Ph2 MeSb)2 C6 H4 ](2+) ([1](2+) ), an antimony-based bidentate Lewis acid obtained by methylation of the corresponding distibine. Unlike the simple stibonium cation [Ph3 MeSb](+) , dication [1](2+) efficiently catalyzes the hydrosilylation of benzaldehyde under mild conditions. The catalytic activity of this dication is correlated to its ability to doubly activate the carbonyl functionality of the organic substrate. This view is supported by the isolation of [1-μ2 -DMF][OTf]2 , an adduct, in which the DMF oxygen atom bridges the two antimony centers.

Synthesis, crystal, and molecular structure of the solvated complex [MoO2(L)] · DMF (L2− = 2-[N-(2-hydroxynaphthylidene)amino]propane-1,2,3-triol anion)

A new dioxomolybdenum(VI) complex, [MoO2(L)] · DMF, where L2− = 2-[N-(2-hydroxynaphthylidene)amino]propane-1,2,3-triol, has been synthesized. Its structure has been determined by X-ray diffraction analysis. The Mo atom is octahedrally coordinated by two oxo ligands that are in cis-positions with respect to each other, two oxygen atoms, the nitrogen atom of the tridentate bis(chelate) ligand L, and the DMF oxygen atom.

Physico-chemical and structural characterization of the binary system phosphoric acid–N,N-dimethylformamide

The binary phosphoric acid (H(3)PO(4))-N,N-dimethylformamide (DMF) system has very different physico-chemical properties depending on composition. This paper summarizes the physico-chemical data newly collected and reported previously on the H(3)PO(4)-DMF system, and proposes structural models for the different regions of composition. The internal hydrogen bonding between pairs of phosphoric acid molecules in cyclic dimeric units is very important as well as the role of the DMF oxygen as hydrogen bond acceptor linking the dimeric phosphoric acid units into polymeric layers and three-dimensional networks.

Synthesis, molecular and supramolecular structure, spectroscopy and electrochemistry of a dialkoxo-bridged diuranyl(VI) compound

The synthesis, molecular and supramolecular structure, spectroscopy and electrochemistry of a dialkoxo-bridged diuranyl(VI) compound [(UO 2) 2(L) 2(dimethylformamide) 2] ( 1) derived from the Schiff base ligand H 2L, obtained on condensation of 3-methoxysalicylaldehyde with 2-aminoethanol, have been described. The compound has been characterized by IR, UV–Vis, NMR and mass spectra, as well as by single crystal X-ray structure determination. The title compound crystallizes in the monoclinic P2 1/ n space group with the following unit cell parameters a = 10.5713(2) Å, b = 11.9895(2) Å, c = 12.9372(2) Å, β = 102.773(3)° and Z = 2. The structure of 1 reveals that it is a dialkoxo-bridged dinuclear compound of uranium(VI) containing two deprotonated ligands, [L] 2−, two dimethylformamide (dmf) molecules and two UO 2 2+ centers. The coordination geometry around the uranium(VI) center is distorted pentagonal bipyramidal; two uranyl oxygens occupy the axial positions, while the basal pentagonal plane is defined by a phenoxo oxygen, two bridging alkoxo oxygens, one imine nitrogen, and one dmf oxygen. Three C–H⋯O type hydrogen bonds involving one uranyl oxygen, two dmf hydrogens and the imine hydrogen link the dinuclear units into a two-dimensional network. The ESI-MS spectrum of 1 in dimethylsulfoxide exhibits two peaks at m/ z = 464.17 and 927.26, which are assignable to [(UO 2) 2L 2H] + (60%) and [(UO 2) 2LH] + (100%) cations, respectively. Cyclic voltammetric measurements of 1 reveal that the uranium(VI) center is reduced quasireversibly at E 1/2 = −1112 mV with Δ E P = 97 mV.

Strong Ferromagnetic Coupling in Linear Mixed μ-Acetato, μ-Hydroxo Trinuclear Copper(II) Complexes withN-sulfonamide derivatives − Synthesis, Structure, EPR and Magnetic Properties

Two new trinuclear copper(II) complexes have been synthesised and structurally characterised: [Cu3(L1)2(CH3COO)2(OH)2(DMF)2] (1) [HL1 = N-(pyrid-2-ylmethyl)benzenesulfonylamide] and [Cu3(L2)2(CH3COO)2(OH)2]∞ (2) [HL2 = N-(pyrid-2-ylmethyl)naphthalenesulfonylamide]. In both complexes the central copper ion has a regular square planar geometry. The coordination spheres of the terminal copper atoms are square pyramidal, the apical positions being occupied by a DMF oxygen atom in 1 and by a sulfonamido oxygen of the contiguous trimer in 2, as a consequence the latter can be considered a chain of trinuclear species. For the two compounds the three copper atoms are in a strict linear arrangement and adjacent coppers are connected by a hydroxo bridge and a bidentate syn-syn carboxylato group. The mixed bridging by a hydroxide oxygen atom and a bidentate carboxylato group leads to a noncoplanarity of the adjacent basal coordination planes with a dihedral angle of 54.4(1)° for compound 1 and 58.34(3)° for compound 2. Susceptibility measurements (2−300 K) reveal a strong ferromagnetic coupling, J = 94.0 and 59.1 cm−1, respectively, in the mixed-bridged moiety leading to a quadruplet ground state that is confirmed by the EPR spectra. The ferromagnetic coupling arising from the countercomplementarity of the hydroxo and acetato bridges has been discussed on the basis of DFT calculations on model compounds. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

(μ-Phenoxo)2CoIIMII (M = Mn, Co, Zn) Complexes with a Co(salen) Entity in a Macrocyclic Framework: Core Structures and Neighboring MII Effects upon Oxygenation at the Co(salen) Center

The phenol-based macrocyclic ligands (L2,3)2- and (L2,4)2-, derived from the [2:1:1] condensation of 2,6-diformyl-4-methylphenol, ethylenediamine, and 1,3-trimethylenediamine or 1,4-tetramethylenediamine, have a salen-like metal-binding site (salen = N,N‘-ethylenedisalicylideneaminate) and a saltn- or salbn-like metal-binding site (saltn = N,N‘-trimethylenedisalicylideneaminate, salbn = N,N‘-tetramethylenedisalicylideneaminate) sharing the phenolic moieties. They form the (μ-phenoxo)2CoIIMII complexes [CoMn(L2,3)(AcO)]ClO4·DMF (1), [CoMn(L2,4)(AcO)]ClO4 (2), [CoCo(L2,3)(AcO)]ClO4 (3), [CoCo(L2,4)(AcO)]ClO4 (4), [CoZn(L2,3)(AcO)]ClO4 (5), and [CoZn(L2,4)(AcO)]ClO4 (6). Complex 1 crystallizes in the monoclinic space group P21/c, with a = 10.027(3) Å, b = 11.713(3) Å, c = 26.821(9) Å, β = 93.85(2)°, V = 3142(1) Å3, and Z = 4. The Co and Mn ions are bridged by the two phenolic oxygens of the macrocycle and an acetate group in the syn-syn mode. The CoII in the salen site is of low-spin and assumes a square-pyramidal geometry with an acetate oxygen at the axial site. The MnII has a cis six-coordinate geometry with respect to the acetate oxygen and the DMF oxygen. The Mn is displaced 0.955 Å from the basal N2O2 least-squares plane. [CoMn(L2,4)(AcO)]ClO4·DMF (2‘) crystallizes in the monoclinic space group P21/c, with a = 10.166(5) Å, b = 11.934(4) Å, c = 27.380(8) Å, β = 93.97(3)°, V = 3313(1) Å3, and Z = 4. It has a dinuclear core similar to that of 1, with square-pyramidal CoII in the salen site and cis six-coordinate MnII in the salbn site. Complex 3 crystallizes in the triclinic space group P1̄, a = 12.118(3) Å, b = 12.156(2) Å, c = 9.977(1) Å, α = 112.49(1)°, β = 99.22(2)°, γ = 77.63(2)°, V = 1321.1(5) Å3, and Z = 2. Both CoII ions in the salen and saltn sites assume a square-pyramidal geometry with a bridging acetate group in the syn-syn mode. The displacement of the Co in the saltn site, from the basal N2O2 least-squares plane toward the apical acetate oxygen, is 0.53 Å. Complex 5 is found to be isostructural with 3. The complexes 1, 2, 4, 5, and 6 are reversibly oxygenated in DMF at 0 °C to afford a μ-peroxo dimer complex [{CoIIIMII(L)(AcO)}2(O22-)]2+. Complex 3 also forms such a μ-peroxo dimer complex but is irreversibly oxidized through an intramolecular-type μ-peroxo complex [CoIIICoIII(L2,3)(AcO)(O22-)]+.

FeIIPbII and FeIII complexes of macrocyclic compartmental ligands: different cyclization in stepwise template synthesis using FeII/PbII or FeIII/PbII pairs

The reaction of [bis(3-formyl-5-methylsalicylidene)ethylenediaminato]iron(II) with diethylenetriamine (dien) in the presence of PbII followed by the addition of NaNCS formed a FeIIPbII complex, [FePb(L1)(NCS)(dmf)(ClO4)] 1, where (L1)2– is a dinucleating macrocyclic compartmental ligand derived from the [2∶1∶1] condensation of 2,6-diformyl-4-methylphenol, ethylenediamine and dien, having “salen”- and “saldien”-like metal-binding sites sharing the phenolic entities. The Fe resides in the “salen” site and the Pb in the “saldien” site: the Fe· · ·Pb intermetallic separation is 3.438(2) A. The Fe assumes a square-pyramidal geometry with an isothiocyanate nitrogen at the apex. The Pb has a seven-coordinate geometry with a dmf oxygen and a perchlorate oxygen at the axial sites. Complex 1 reacts with molecular dioxygen to give a µ-oxo complex [{FePb(L1)(NCS)(dmf)(ClO4)}2(O)]. A similar reaction of chloro[bis(3-formyl-5-methylsalicylidene)ethylenediaminato]iron(III) with dien in the presence of PbII formed a mononuclear FeIII complex [Fe(H2L2)(NCS)][ClO4]2·dmf 2, where H2L2 is a macrocycle derived from the [2∶2] condensation of 2,6-diformyl-4-methylphenol and dien. The Fe resides in one “saldien” site and assumes an octahedral geometry with an isothiocyanate nitrogen in one apical position. Another metal-binding site formed with dien shows unusual condensation; one primary amino group of the dien condenses with one formyl group to form an usual CN linkage and the remaining primary and secondary amino groups of the dien condense with another formyl group to form a five-membered imidazoline ring.

Macrocyclic Heterodinuclear Zn(II)Pb(II) Complexes: Synthesis, Structures, and Hydrolytic Function toward Tris(p-nitrophenyl) Phosphate.

A heterodinuclear Zn(II)Pb(II) complex ZnPb(L)(ClO(4))(2).2H(2)O (1) has been obtained where (L)(2)(-) is an unsymmetric macrocycle derived from the 2:1:1 condensation of 2,6-diformyl-4-methylphenol, ethylenediamine and diethylenetriamine and has the "salen"- and "saldien"-like metal-binding sites sharing the phenolic moiety. Its DMF adduct, ZnPb(L)(ClO(4))(2).MeOH.2DMF (1'), crystallizes in the triclinic space group P&onemacr; with a = 14.457(4) Å, b = 14.795(6) Å, c = 10.307(9) Å, alpha = 109.04(5) degrees, beta = 96.24(5) degrees, gamma = 102.56(3) degrees, V = 1995(2) Å(3), and Z = 2. The refinement converges with R = 0.058 and R(w) = 0.060 for 3532 reflections with |F(0)| > 3sigma(|F(0)|). It has a discrete heterodinuclear core with the Zn(II) in the "salen" site and the Pb(II) in the "saldien" site of the macrocycle (L)(2)(-). The Zn has a square-pyramidal geometry together with a methanol oxygen, and the Pb has a seven-coordinate geometry together with one DMF oxygen and one perchlorate oxygen. The complex 1 is converted into [ZnPb(L)(OH)ClO(4)]H(2)O (2) under a weak alkaline condition. Its anhydrous form, [ZnPb(L)(OH)]ClO(4) (2), crystallizes in the monoclinic space group C2/c with a = 25.835(4) Å, b = 13.190(6) Å, c = 16.553 Å, beta = 106.31(2) degrees, V = 5413(2) Å(3), and Z = 8. The refinement converges with R = 0.038 and R(w) = 0.029 for 3944 reflections with |F(0)| > 3sigma(|F(0)|). It has a dimer structure of a dinuclear {ZnPb(L)(OH)}(+) unit having the Zn(II) in the "salen" site and the Pb(II) in the "saldien" site of the macrocycle. The hydroxide is bound to the Zn(II) to afford a square-pyramidal geometry about the metal. The dimeric core [ZnPb(L)(OH)](2)(2+) is formed by the bridge of the hydroxide oxygen to the Pb of the adjacent molecule and vice versa. The geometry about the Pb in the dimer structure is a pentagonal pyramid showing a distortion to "umbrella-like" structure, with the bridging hydroxide oxygen at the apex. In a DMSO solution, an equilibrium exists between the dimeric and monomeric species: [{ZnPb(L)(OH)}(2)](2+) right harpoon over left harpoon 2[ZnPb(L)(OH)](+). On the basis of (31)P NMR and visible spectra, 2 is shown to hydrolyze tris(p-nitorophenyl) phosphate (TNP) into bis(p-nitrophenyl) phosphate (BNP) in DMSO. 1 also exhibits a low activity to hydrolyze TNP into BNP due to the equilibrium [ZnPb(L)(H(2)O)](2+) right harpoon over left harpoon [ZnPb(L)(OH)](+) + H(+). From the reaction mixture with 2, a BNP complex [ZnPb(L)(BNP)]ClO(4) (3) has been isolated. 3 crystallizes in the triclinic space group P&onemacr; with a = 13.494(9) Å, b = 13.88(1) Å, c = 12.765(8) Å, alpha = 94.71(6) degrees, beta = 97.02(6) degrees, gamma = 61.68(5) degrees, V = 2088(2) Å(3), Z = 2. The refinement converges with R = 0.044 and R(w) = 0.056 for 6070 reflections with |F(0)| > 3sigma(|F(0)|). The BNP(-) group bridges the pair of metal ions through its two oxygens, together with two phenolic oxygens of (L)(2)(-). On the basis of the above findings, a mechanistic scheme for the TNP hydrolysis by 2 is proposed; a TNP molecule is bound to the Pb center, and the hydroxide on the adjacent Zn ion attacks the phosphorus nucleus of TNP, leading to the formation of the BNP complex 3.

Dioxygen Oxidation of Coordinated Nitrosyl to Nitro on Dmf-Bridged Dinuclear CoPb Complex

Abstract The CoIIPbII complex [CoPb(L)(CH3OH)(ClO4)2] reacts with nitrogen monoxide to give the nitrosyl complex [CoPb(L)(NO)(dmf)2(ClO4)]ClO4 (1), where H2L is a dinucleating macrocycle derived from the [2 : 1 : 1] condensation of 2,6-diformyl-4-methylphenol, ethylenediamine, and diethylenetriamine and has a “salen”- and a “saldien”-like metal-binding site sharing the phenolic entities. 1 crystallizes in the triclinic space group , a = 12.729(4), b = 17.103(6), c = 10.548(4) Å, α = 107.42(4)°, β = 106.18(2)°, γ = 101.33(3)°, V = 2003(1) Å3, and Z = 2. The refinement converges with R = 0.045 and Rw = 0.049 for 3768 reflections with I > 3.00σ(I). The Co resides in the “salen” site and the Pb in the “saldien” site. The metal ions are bridged by the two phenolic oxygens of L2− and a dmf oxygen, in the Co–Pb intermetallic separation of 3.511(2) Å. The Co–O(dmf) and O(dmf)–Pb bond distances are 2.14(1) and 3.072(8) Å, respectively. The NO coordinates to the Co at the axial site trans to the bridging dmf oxygen, providing a six-coordinate geometry about the metal; the Co–N(nitrosyl) distance is 1.92(1) Å and the Co–N–O angle is 117(1)°. The Pb has an eight-coordinate geometry together with the bridging dmf oxygen, a terminal dmf oxygen and a perchlorate oxygen. The nitrosyl complex 1 is oxidized with molecular oxygen to the nitro complex [CoPb(L)(NO2)(dmf)2(ClO4)]ClO4 (2). 2 crystallizes in the triclinic space group , a = 12.748(4), b = 17.139(5), c = 10.359(3) Å, α = 106.34(3)°, β = 106.44(3)°, γ = 101.42(3)°, V = 1986(1) Å3, and Z = 2. The refinement converges with R = 0.039 and Rw = 0.042 based on 6202 reflections with I > 3.00σ(I). 2 has a dinuclear core very similar to that of 1, bearing an NO2 group instead of an NO group. The Co–N(nitro) bond distance is 1.889(6) Å. 1H NMR, 13C NMR, and 13C–1H COSY spectroscopies indicate that the dmf-bridged dinuclear cores of 1 and 2 are retained in solution.

Diphenoxo-bridged NiCo and CuCo complexes of macrocyclic ligands: synthesis, structure and electrochemical behaviour

Heterodinuclear di-µ-phenoxo-M II Co II (M = Ni or Cu) complexes have been derived from phenol-based dinucleating ligands (L m,n ) 2- , comprising of two 2,6-di(iminomethyl)-4-methylphenolate entities linked by two lateral chains (CH 2 ) m (m = 2 or 3) and (CH 2 ) n (n = 3 or 4) at the imino nitrogens. The crystal structure of [CuCo(L 2,3 )(dmf) 2 (H 2 O)][ClO 4 ] 2 (dmf = dimethylformamide) has been determined. The copper ion resides at the N 2 O 2 site formed by the ethylene lateral chain and assumes a square-pyramidal geometry together with a dmf oxygen at the apex. The Co at the site of the trimethylene lateral chain assumes a pseudo-octahedral geometry together with a dmf and a water molecule at the axial positions. The Cu · · · Co separation doubly bridged by the phenolic oxygens is 2.998(2) A. The NiCo complexes are paramagnetic (S Ni = 0), whereas the CuCo complexes show a strong antiferromagnetic interaction between the two metal ions. Cyclic voltammograms of the NiCo complexes show two quasi-reversible couples attributable to the stepwise reductions: Ni II Co II → Ni I Co II → Ni I Co I . The Ni I Co II and Ni I Co I complexes were prepared in solution by coulometry and characterized by visible spectroscopy. Similarly, the CuCo complex of (L 3,3 ) 2- is reduced stepwise to Cu I Co II and then to Cu I Co I . On the other hand, the CuCo complexes of (L 2,3 ) 2- and (L 2,4 ) 2- showed unusual electrochemical behaviour at the electrode suggesting a scrambling or site exchange of the metal ions.

Synthesis and Structural Systematics of Nitrogen Base Adducts of Group 2 Salts. X. Some Mixed-Ligand Complexes of Group 2 Metal Halides With 2,2':6',2"-Terpyridine and Oxygen Donors

Room-temperature single-crystal X-ray structural characterizations are recorded for a variety of adducts of Group 2 metal halides with 2,2':6',2?-terpyridine ( tpy ) from various hydroxylic solvents. [Mg( tpy )2][Mg( tpy )(OH2)3] Br4.PriOH (1) is triclinic, Pī, a 19.352(6), b 12.852(5), c 11.463(3) Ǻ, α 110.95(3), β 99.04(2), γ 98.81(3)°, Z = 2 f.u .; conventional R on ׀ F ׀ at convergence was 0.056 for No 4398 independent 'observed' (I > 3σ(I)) reflections. In the [Mg( tpy )2]2+ ion, Mg-N(central; distal) are 2.099(9), 2.09(1); 2.152(9)-2.212(8) Ǻ, while in [Mg( tpy )(OH2)3]2+, Mg-N(central; distal) are 2.139(7); 2.206(9), 2.222(9) Ǻ, while Mg-O trans to these are 2.042(6); 2.082(9), 2.097(8) Ǻ. [Mg( tpy )(OH2)2( MeOH )] Cl2 (2) is triclinic, Pī, a 14.049(7), b 8.354(4), c 8.301(2) Ǻ, α 74.25(3), β 73.05(3), γ 80.37(4)°, Z = 2 f.u., R 0.064 for No 2417. In the cation, Mg-N(central; distal) are 2.125(4); 2.203(4), 2.218(4) Ǻ; Mg-O( MeOH ) is trans to Mg-N(central), being 2.013(4) Ǻ; Mg-O(OH2) are 2.067(4) and 2.063(4) Ǻ. [CaCl2( tpy )( dmf )2 (3) ( dmf = N,N- dimethylformamide ) is monoclinic, C2/c, a 23.27(2), b 11.225(6), c 16.517(8) Ǻ, β 109.56(5)°, Z = 4 centrosymmetric dimers, R 0.061 for No 985. The calcium atoms are linked by a pair of μ-chlorines, CaCl2Ca, and are seven-coordinate, N3Ca(μ-Cl )4 being broadly coplanar in the equatorial plane of a pentagonal bipyramidal array, with the other chlorine and the dmf oxygen trans and axial.