Thermodynamic, kinetic and solid-state study of divalent metal complexes of 1,4,8,11-tetraazacyclotetradecane (cyclam) bearing two trans (1,8-)methylphosphonic acid pendant arms

Divalent metal complexes of macrocyclic ligand 1,4,8,11-tetraazacyclotetradecane-1,8-bis(methylphosphonic acid)) (1,8-H4te2p, H4L) were investigated in solution and in the solid state. The majority of transition-metal ions form thermodynamically very stable complexes as a consequence of high affinity for the nitrogen atoms of the ring. On the other hand, complexes with Mn2+, Pb2+ and alkaline earth ions interacting mainly with phosphonate oxygen atoms are much weaker than those of transition-metal ions and are formed only at higher pH. The same tendency is seen in the solid state. Zinc(II) ion in the octahedral trans-O,O-[Zn(H2L)] complex is fully encapsulated within the macrocycle (N4O2 coordination mode with protonated phosphonate oxygen atoms). The polymeric {[Pb(H2L)(H2O)2].6H2O}n complex has double-protonated secondary amino groups and the central atom is bound only to the phosphonate oxygen atoms. The phosphonate moieties bridge lead atoms creating a 3D-polymeric network. The [{(H2O)5Mn}2(micro-H2L)](H2L).21H2O complex contains two pentaaquamanganese(II) moieties bridged by a ligand molecule protonated on two nitrogen atoms. In the complex cation, oxygen atoms of the phosphonate groups on the opposite sites of the ring occupy one coordination site of each metal ion. The second ligand molecule is diprotonated and balances the positive charge of the complex cation. Complexation of zinc(II) and cadmium(II) by the ligand shows large differences in reactivity of differently protonated ligand species similarly to other cyclam-like complexes. Acid-assisted dissociations of metal(II) complexes occur predominantly through triprotonated species [M(H3L)]+ and take place at pH < 5 (Zn2+) and pH < 6 (Cd2+).     

Cyclam (1,4,8,11-tetraazacyclotetradecane) with one methylphosphonate pendant arm: a new ligand for selective copper(ii) binding

The new ligand, [(1,4,8,11-tetraazacyclotetradecan-1-yl)methyl]phosphonic acid (H(2)te1P, H(2)L), was synthesized and its complexing properties towards selected metal ions were studied potentiometrically. The ligand forms a very stable complex with copper(ii)(logbeta(CuL)= 27.34), with a high selectivity over binding of other metal ions (i.e. logbeta(ZnL)= 21.03). The crystal structures of the free ligand (in its protonated form with bromide as counter-ion) and two copper(ii) complexes (obtained by crystallization at various pH) were determined. The free ligand adopts the common conformation for such macrocycles with the protonated nitrogen atoms in the corners of a virtual rectangle. In the trans-Br,O-[Cu(Br)(Hte1P)].H(2)O species, the central metal ion is surrounded by four in plane nitrogen atoms, one oxygen atom of the pendant moiety in the apical position and a bromide anion positioned trans to the oxygen atom, forming a distorted octahedral coordination sphere. In the compound [Cu(H(2)te1P)][Cu(Hte1P)]Br(3).6H(2)O, obtained from a highly acidic solution, the bromide anions are placed further away from the copper(ii) ion and the coordination environment (N(4)O) is thus square-pyramidal. In both structures, the protons are associated with non-coordinated phosphonate oxygen atoms.     

Cobalt phosphonates: an unusual polymeric cobalt phosphonate containing a clathrated phosphonate anion and a layered bisphosphonate

Novel cobalt phosphonates [Co(H(2)O)(4)(H(4)L)][H(2)L].2H(2)O, 1, and Co(2)(H(2)O)(2)(L), 2, have been synthesized from 1,8-octylenediphosphonic acid (H(4)L). 1 has been fully characterized by X-ray single-crystal data, TGA, IR spectroscopy, and chemical analysis. The compound crystallizes in the triclinic space group P1 with a = 5.5415(8) A, b = 8.6382(8) A, c = 16.794 (2) A, alpha = 87.694(2) degrees, beta = 80.859(2) degrees, gamma = 76.005(2) degrees, V = 770.11(19) A(3), and Z = 1. A cobalt atom lies in the center of symmetry and is octahedrally coordinated by two oxygen atoms from two undissociated diphosphonic ligands H(4)L and four molecules of water. The cobalt atom and undissociated ligand H(4)L are combined to form polymeric chains along the c-axis, resulting in the formation of a one-dimensional framework. The positive charge on the cobalt atom remains upon coordination and is balanced by a negatively charged uncoordinated ligand (H(2)L) found as a clathrate in the lattice. Two lattice water molecules, hydrogen-bonded with the coordinated and uncoordinated ligands, complete the structure. The metal phosphonate chains are held together and bridge the uncoordinated anionic ligands by a number of strong hydrogen bonds, which make the structure possible. Cobalt phosphonate 2 has been characterized by TGA measurements, IR spectroscopy, and chemical analysis. The compound has a layered structure with an interlayer spacing of 14.26 A. Metal phosphonate layers are cross-linked by hydrocarbon chains. The water molecules are coordinated to the metal atom. According to IR data, compound 2 contains two equivalent PO bonds and one different PO bond, which may be a result of the different types of Co-O-P connectivity within one phosphonic group.     

Metal carboxylate-phosphonate hybrid layered compounds: synthesis and single crystal structures of novel divalent metal complexes with N-(phosphonomethyl)iminodiacetic acid

Two novel divalent metal complexes with N-(phosphonomethyl)iminodiacetic acid, H(2)O(3)PCH(2)N(CH(2)CO(2)H)(2) (H(4)PMIDA), [Co(2)(PMIDA)(H(2)O)(5)] x H(2)O, 1, and [Zn(2)(PMIDA)(CH(3)CO(2)H)] x 2H(2)O, 2, have been synthesized and structurally characterized. The structure of complex 1 features two different kinds of Co(II) layers, namely, a cobalt phosphonate layer along the <100> plane and a cobalt carboxylate layer along the <300> plane. The Co(II) atoms in the phosphonate layer are octahedrally coordinated by 4 aqua ligands and 2 oxygen atoms from two phosphonic acid groups. Two Co(II) octahedra are bridged by a pair of phosphonic groups into a dimeric unit, and such dimers are interconnected into a layer through hydrogen bonding between aqua ligands. The Co(II) atoms in the carboxylate layer are octahedrally coordinated by a chelating PMIDA ligand, one aqua ligand, and one phosphonic oxygen atom from the neighboring PMIDA ligand. These Co(II) octahedra are interlinked by bridging carboxylic groups into a one-dimensional chain along the c-axis; such chains are held together by hydrogen bonds formed between carboxylic oxygen atoms and lattice water molecules, in such a way as to form a layer along the <300> direction. Two such layers are interconnected into a double layer via hydrogen bonding. These double layers are further interconnected with the Co(II) phosphonate layers through phosphonate tetrahedra along the a direction, resulting in the formation of a complicated three-dimensional network. The crystal structure of 2 contains a metal phosphonate and metal carboxylate hybrid layer along the <202> plane. One of the two zinc atoms in the asymmetric unit is tetrahedrally coordinated by four oxygen atoms from two phosphonic acid groups and two carboxylic groups; the other zinc atom is 5-coordinated by three oxygen atoms and a nitrogen atom from a chelating PMIDA ligand and one oxygen atom from the acetic acid. The above two types of zinc metal ions are interconnected by bridging carboxylic and phosphonic groups, resulting in the formation of a layered structure.     

Complexes formed between nitrilotris(methylenephosphonic acid) and M(2+) transition metals: isostructural organic-inorganic hybrids

Nitrilotris(methylenephosphonic acid) (NTP, [N(CH(2)PO(3)H(2))(3)]) recently has been found to form three-dimensional porous structures with encapsulation of templates as well as layered and linear structures with template intercalation. It was, therefore, of interest to examine the type of organic-inorganic hybrids that would form with metal cations. Mn(II) was found to replace two of the six acid protons, while a third proton bonds to the nitrilo nitrogen, forming a zwitter ion. Two types of compounds were obtained. When the ratio of acid to Mn(II) was less than 10, a trihydrate, Mn[HN(CH(2)PO(3)H)(3)(H(2)O)(3)] (2) formed. Compound 2 is monoclinic P2(1)/c, with a = 9.283(2) A, b = 16.027(3) A, c = 9.7742(2) A, beta = 115.209(3) degrees, V = 1315.0(5) A(3), and Z = 4. The Mn atoms form zigzag chains bridged by two of the three phosphonate groups. The third phosphonate group is only involved in hydrogen bonding. The metal atoms are octahedrally coordinated with three of the sites occupied by water molecules. Adjacent chains are hydrogen-bonded to each other through POH and HN donors, and the additional participation of all the water hydrogens in H-bonding results in a corrugated sheet-like structure. Use of excess NTP at a ratio to metal of 10 to 1 yields an anhydrous compound Mn[HN(CH(2)PO(3)H)(3)] (1), P2(1)/n, a = 9.129(1) A, b = 8.408(1) A, c = 13.453(1) A, beta = 97.830(2) degrees, V = 1023.0(2) A(3), and Z = 4. Manganese is five coordinate forming a distorted square pyramid with oxygens from five different phosphonate groups. The sixth oxygen is 2.85 A from an adjacent Mn, preventing octahedral coordination. All the protonated atoms, three phosphonate oxygens and N, form moderately strong hydrogen bonds in a compact three-dimensional structure. The open-structured trihydrate forms a series of isostructural compounds with other divalent transition metal ions as well as with mixed-metal compositions. This is indicative that the hydrogen bonding controls the type of structure formed irrespective of the cation.     

Spontaneously organizing metal connectors as supramolecular structure directors of two- and three-dimensional organometallic assemblies

The supramolecular interplay of Me(3)Sn(+) and [M(CN)(2n)](n-) ions (n=3 and 4) with either 4,4'-bipyridine (bpy), trans-bis(4-pyridyl)ethene (bpe) or 4cyanopyridine (cpy) in the presence of H(2)O has been investigated for the first time. Crystal structures of the six novel assemblies: [(Me(3)Sn)(4)Mo(IV)(CN)(8).2 H(2)O.bpy] (8) and [(Me(3)Sn)(4)Mo(IV)(CN)(8).2 H(2)O.bpe] (8 a; isostructural), [(Me(3)Sn)(3)Fe(III)(CN)(6).4 H(2)O.bpy] (9), [(Me(3)Sn)(3)Co(III)(CN)(6).3 H(2)O.3/2 bpy] (10), [(Me(3)Sn)(4)Fe(II)(CN)(6).H(2)O.3/2 bpy] (11), and [(Me(3)Sn)(4)Ru(II)(CN)(6).2 H(2)O.3/2 cpy] (12) are presented. H(2)O molecules are usually coordinated to tin atoms and involved in two significant O-H.N hydrogen bonds, wherein the nitrogen atoms belong either to bpy (bpe, cpy) molecules or to M-coordinated cyanide ligands. Extended supramolecular assemblies such as -CN-->Sn(Me(3))<--O(H.)H.N(L)N.HO(H.)-->Sn(Me(3))<--NC- (L=bpy, bpe or cpy) function as efficient metal connectors (or spacers) in the structures of all six compounds. Only in the three-dimensional framework of 11, one third of all bpy molecules is involved in coordinative N-->Sn bonds. The supramolecular architecture of 9 involves virtually non-anchored (to cyanide N atoms), Me(3)Sn(+) units with a strictly planar SnC(3) skeleton, and two zeolitic H(2)O molecules. Pyrazine (pyz) is surprisingly reluctant to afford assemblies similar to 8-12, however, the genuine host-guest systems [(Me(3)Sn)(4)Mo(CN)(8).0.5pyz] and [(Me(3)Sn)(4)Mo(CN)(8).pym] (pym=pyrimidine) could be isolated and also structurally characterized.     

Synthesis and structures of beta-diketiminatotin(II) halides, an amide and of Sn(=E)[{N(R)C(Ph)}2CH](NR2) (E = S or Se, R = SiMe3)

Treatment of [Li(L1)]2 (1) or K(L2) (2) with SnX2 in Et2O yielded the heteroleptic beta-diketiminatotin(II) halides Sn(L1)Cl (3a), Sn(L1)Br (3b) or Sn(L2)Cl (4), even when an excess of the alkali metal beta-diketiminate was used [L1={N(R)C(Ph)}2CH, L2={N(R)C(Ph)CHC(But)N(R)}, R = SiMe3]. From and half an equivalent each of SnCl2.2H2O and SnCl2, or one equivalent of SnCl2.2H2O, the product was Sn(L3)Cl (5) or Sn(L4)Cl (6), in which one or both of the N-R bonds of L1 had been hydrolytically cleaved; the compound Sn(L5)Cl (7) was similarly obtained from and an equivalent portion of SnCl2.2H2O [L3={N(R)C(Ph)CHC(But)N(H)}, L4={N(H)C(Ph)CHC(But)N(H)} and L5={N(H)C(Ph)}2CH]. The halide exchange between 3a and 3b, studied by two-dimensional (119)Sn{1H}-NMR spectroscopy, is attributed to implicate a (mu-Cl)(mu-Br)-dimeric intermediate or transition state. The 13C{1H}-NMR spectra of or showed two distinct resonances for each group, which coalesced on heating, corresponding to DeltaG(338 K)= 69.4 (3a) or 72.8 (3b) kJ mol(-1). The chloride ligand of was readily displaced by treatment with NaNR2, CF3SO3H or CH2(COPh)2, yielding Sn(L1)X [X = NR2 (8), O3SCF3 (9) or {OC(Ph)}2CH (10)]. Oxidative addition of sulfur or selenium to gave the tin(IV) terminal chalcogenides Sn(E)(L1)(NR2)[E = S (11) or Se (12)]. The X-ray structures of the cocrystal of 3a/3b and of the crystalline compounds 5, 6, 8, 11 and are presented, as well as multinuclear NMR spectra of each of the new compounds.     

Synthesis and X-ray Powder Structures of Two Lamellar Copper Arylenebis(phosphonates)

Reaction of copper salts with 1,4-phenylenebis(phosphonic acid) yielded a conventional layered compound, Cu(2)[(O(3)PC(6)H(4)PO(3))(H(2)O)(2)], while a similar reaction with 4,4'-biphenylenebis(phosphonic acid) resulted in a new lamellar structure with composition Cu[HO(3)P(C(6)H(4))(2)PO(3)H]. The structures of these compounds were solved ab initio by using X-ray powder diffraction data. The crystals of the phenylenebis(phosphonate) compound are monoclinic, space group C2/c, with a = 18.8892(4) ?, b = 7.6222(2) ?, c = 7.4641(2) ?, beta = 90.402(2) degrees, and Z = 4. The layer structure in this case is similar to that in copper phenylphosphonate, Cu[O(3)PC(6)H(5)]. The metal atoms display a distorted square pyramidal geometry where four of the coordination sites are occupied by the phosphonate oxygens. The remaining site is filled by an oxygen atom of the water molecule. Adjacent metal-O(3)PC layers are covalently pillared by the phenyl group of the phosphonates to create a 3-dimensional structure. Cu[HO(3)P(C(6)H(4))(2)PO(3)H] is triclinic, space group P&onemacr;, with a = 4.856(2) ?, b = 14.225(5) ?, c = 4.788(2) ?, alpha = 97.85(1) degrees, beta = 110.14(1) degrees, gamma = 89.38(1) degrees, and Z = 1. The structure in this case, ideally consists of linear chains of copper atoms. The copper atoms are bridged by centrosymmetrically related phosphonate groups utilizing two of their oxygen atoms. This binding mode leads to square planar geometry for the copper atoms. The third oxygen atom of the phosphonate is protonated and is involved in linking adjacent linear chains through hydrogen bonds. At the same time, these hydroxyl oxygens interact weakly (Cu-O = 3.14 ?) with the copper atoms of the adjacent chain. Considering these long Cu-O interactions, the geometry of the copper atom may be described as distorted square bipyramidal. As in the phenylphosphonate structure, the biphenyl groups covalently link the Cu-O(3)PC networks in the perpendicular direction.     

Influence of the metal size in the structure of the complexes derived from a pentadentate [N(3)O(2)] hydrazone

The influence of the metal size in the nuclearity of the complexes derived from the hydrazone ligand 2,6-bis(1-salicyloylhydrazonoethyl)pyridine [H(4)daps] has been investigated. We have synthesised a series of new complexes [M(H(x)daps)] x yH(2)O, (x = 2,3; y = 0-3) with M = Ag (1), Cd (2), Al (3), Sn (4) and Pb (6), using an electrochemical procedure. The crystal and molecular structures have been determined for the mononuclear complexes [Sn(H(2)daps)(H(2)O)(2)] x 4H(2)O (5) and [Pb(H(2)daps)(CN)][Et(4)N] (7). Complex is the first neutral Sn(II) complex derived from a pentadentate hydrazone Schiff base ligand. Complex shows the lead coordinated to the hydrazone donor set and a cyanide ligand, being the first reported complex with the lead atom coordinated to a monodentate cyanide group. Additionally, we have synthesised the lead complex using chemical conditions, in the presence of sodium cyanide which allowed us to isolate the neutral complex [Pb(H(2)daps)] (8). Evaporation of these mother liquors led the novel compound [Pb(Hdaphs)(CH(3)COO)] (9). Complex 9 shows the initial ligand hydrolysed in one of the imine bonds giving rise to a new tetradentate ligand [H(2)daphs] coordinated to the lead atom and a bidentate acetate group. Moreover, the solution behaviour of the complexes has been investigated by (1)H, (113)Cd, (117)Sn and (207)Pb NMR techniques. In particular multinuclear NMR has provided new useful data to correlate factors such as oxidation state, coordination number and nature of the kernel donor atoms due to the new coordination found in complexes 5 and 7. The comparative study of the structures of the complexes derived from this pentadentate [N(3)O(2)] hydrazone ligand let us to conclude that the metal size is a key factor to control the nuclearity of the complexes derived from the ligand [H(4)daps].     

Synthesis and properties of V6O16CU(C4H4N2)2 x (H2O)(0.22(1)): charge density matching of a metal-segregated layer structure

A metal-segregated layered compound, containing square nets of Cu(pyz)(2)(2+) and buckled V(6)O(16)(2)(-) layers, has been synthesized using hydrothermal techniques to have the composition V(6)O(16)Cu(C(4)H(4)N(2))(2) x (H(2)O)(0.22(1)) (C(4)H(4)N(2) = pyrazine, pyz). The Cu(II) square nets are nearly regular and undergo an antiferromagnetic transition at 8 K. In contrast to the plethora of recently synthesized metal-oxide clusters, chains, and networks in the VO(x)/M/L (M = late transition element; L = organonitrogen ligand) system, this compound is a relatively rare example that contains two different metals distributed into distinct layers. An application of charge density matching to form layered structures is postulated.     

N,N''''-(2-苯并咪唑基甲基)亚氨基甲基膦酸的双核镍化合物Ni2(bbimp)2(4,4''''-bipy)(H2O)2·2H2O和Ni2(bbimp)2(H2O)2][Ni(bbimp)(H2O)2]2·4H2O的晶体结构和磁学性质

该文报道了N,N′-(2-苯并咪唑基甲基)亚氨基甲基膦酸{bbimpH_2,[(C7H5N2)CH2]2NCH2PO3H2}的2个镍化合物Ni2(bbimp)2(4,4′-bipy)(H2O)2·2H2O(1)和[Ni2(bbimp)2(H2O)2][Ni(bbimp)(H2O)2]2·4H2O(2)。化合物1是4,4′-联吡啶作为桥连配体的中性双核结构。化合物2含有1个中性的[Ni2(bbimp)2(H2O)2]双核分子与2个中性的[Ni(bbimp)(H2O)2]单核分子。双核分子单元中的2个Ni!离子被2个膦酸氧桥连。在化合物2中,膦酸氧桥连的2个Ni!离子之间存在铁磁性相互作用。     

New types of metal squarato-phosphonates: condensation of aminodiphosphonate with squaric acid under hydrothermal conditions

The syntheses and crystal structures of the first copper(I) phosphonate, Cu2(H3L)(bipy)(2).2H2O 1 (H5L = C4HO3N(CH2PO3H2)2), which is also the first example of metal phosphonates formed by a type of organic reaction, and a novel luminescent Mn(II) squarate diphosphonate, {Mn[NH(CH2PO3H)2](H2O)2}2{Mn(C4O4)(H2O)4}.(C4H2O4) 2, have been reported. The structure of 1 features a layer architecture in which the Cu(I) centers are three coordinated, and the newly formed ligand acts as a bidentate metal linker. Compound 2 is composed of 1D chains of Mn[NH(CH2PO3H)2](H2O)2, 1D chains of {Mn(C4O4)(H2O)4}, as well as the neutral squaric acid molecules. These three types of building units are interconnected via hydrogen bonding.     

Hydrolysis of tin(II) neo-pentoxide: syntheses, characterization, and X-ray structures of [Sn(ONep)(2)](infinity), Sn(5)(mu(3)-O)(2)(mu-ONep)(6), and Sn(6)(mu(3)-O)(4)(mu-ONep)(4) where ONep = OCH(2)CMe(3)

The reaction of [Sn(NMe(2))(2)](2) (1) with 4 equiv of HOCH(2)CMe(3) (HONep) leads to the isolation of [Sn(ONep)(2)](infinity) (2). Each Sn atom is four coordinated with mu-ONep ligands bridging the metal centers; however, if the free electrons of the Sn(II) metal center are considered, each Sn center adopts a distorted trigonal bipyramidal (TBP) geometry. Through (119)Sn NMR experiments, the polymeric compound 2 was found to be disrupted into smaller oligomers in solution. Titration of 2 with H(2)O led to the identification of two unique hydrolysis products characterized by single-crystal X-ray diffraction as Sn(5)(mu(3)-O)(2)(mu-ONep)(6) (3) and Sn(6)(mu(3)-O)(4)(mu-ONep)(4) (4). Compound 3 consists of an asymmetrical molecule that has five Sn atoms arranged in a square-based pyramidal geometry linked by four basal mu-ONep ligands, two facial mu(3)-O, and two facial mu-ONep ligands. Compound 4 was solved in a novel octahedral arrangement of six Sn cations with an asymmetric arrangement of mu(3)-O and mu-ONep ligands that yields two square base pyramidal and four pyramidal coordinated Sn cations. These compounds were further identified by multinuclear ((1)H, (13)C, (17)O, and (119)Sn) solid-state MAS and high resolution, solution NMR experiments. Because of the complexity of the compounds and the accessibility of the various nuclei, 2D NMR experiments were also undertaken to elucidate the solution behavior of these compounds. On the basis of these studies, it was determined that while the central core of the solid-state structures of 3 and 4 is retained, dynamic ligand exchange leads to more symmetrical molecules in solution. Novel products 3 and 4 lend structural insight into the stepwise hydrolysis of Sn(II) alkoxides.     

Bis(diamino-diamido)-tetrathiafulvalene, a redox active sensor for proton, anions, and cations

A bis(diamino-diamido) tetrathiafulvalene (TTF) derivative H(4)L(2) has been designed and synthesized. Experiments of pH titration reveal that integrating the redox active TTF unit with the diamino-diamido moiety adds new properties to the traditional ligand. Oxidation of the TTF moiety increases the acidity of the amido group, and the coordination of metal ions is also sensitive to the oxidation state of the ligand. This compound is capable of acting as a leaving or accepting ligand for proton and metal ions. The electrochemistry of the protonated TTF derivative of H(4)L(2) was studied in the presence of a series of oxo anions and metal cations. The results indicate that the redox potentials selectively respond to HC(2)O(4)(-) and SO(4)(2-) anions, and Ni(II) and Cu(II) cations. Solid-state structures of a cation-anion salt H(8)L(2)·2SO(4)·8H(2)O and a nickel coordination compound [Ni(2)L(2)]·2DMF have been characterized by means of X-ray crystallography which are helpful in understanding the inter-ion interactions.     

New lead inorganic-organic hybrid microporous and layered materials: synthesis,properties, and crystal structures

Two new lead(II) phosphonates, namely, Pb2[PMIDA]*1.5H2O (1) (H4PMIDA = H2O3PCH2N(CH2CO2H)2) and Pb(H2L) (2) (H4L = CH3N(CH2PO3H2)2), have been synthesized by hydrothermal reactions at 150 degrees C. Complex 1 crystallized in tetragonal P42/n with cell dimensions of a = 17.317(7) and c = 7.507(5) A and Z = 8. In complex 1, Pb(1) is 6-coordinated by chelation in a tetradentate fashion by a PMIDA ligand (3 O, 1 N) and two phosphonate oxygen atoms from neighboring Pb(PMIDA) units in a severely distorted octahedral geometry, whereas Pb(2) is 6-coordinated by 4 carboxylate and 2 phosphonate oxygen atoms also with a severely distorted octahedral environment. These two different types of Pb(II) ions are interconnected through bridging carboxylate and phosphonate groups, resulting in a 3D network with micropores, whose cavity is filled by lattice water molecules interlinked via hydrogen bonds. Each PMIDA ligand bridges with 8 Pb(II) ions (3 Pb(1) and 5 Pb(2)). Complex 2 is orthorhombic, P2(1)2(1)2(1), with a = 7.382(5), b = 7.440(6), and c = 30.75(2) A and Z = 8. The structure of 2 features a 2D double lead(II) phosphonate layer along the ab plane. Each lead(II) ion is 5-coordinated by five phosphonate oxygen atoms from four ligands in a distorted trigonal bipyramid geometry. These double layers are further interconnected via hydrogen bonds between the protonated and uncoordinated phosphonate oxygens along the c-axis.     

Design and synthesis of binucleating macrocyclic clefts derived from Schiff-base calixpyrroles

The syntheses, characterisation and complexation reactions of a series of binucleating Schiff-base calixpyrrole macrocycles are described. The acid-templated [2+2] condensations between meso-disubstituted diformyldipyrromethanes and o-phenylenediamines generate the Schiff-base pyrrolic macrocycles H(4)L(1) to H(4)L(6) upon basic workup. The single-crystal X-ray structures of both H(4)L(3).2 EtOH and H(4)L(6).H2O confirm that [2+2] cyclisation has occurred, with either EtOH or H2O hydrogen-bonded within the macrocyclic cleft. A series of complexation reactions generate the dipalladium [Pd2(L)] (L=L(1) to L(5)), dinickel [Ni2(L(1))] and dicopper [Cu2(L)] (L=L(1) to L(3)) complexes. All of these complexes have been structurally characterised in the solid state and are found to adopt wedged structures that are enforced by the rigidity of the aryl backbone to give a cleft reminiscent of the structures of Pacman porphyrins. The binuclear nickel complexes [Ni2(mu-OMe)2Cl2(HOMe)2(H(4)L(1))] and [Ni2(mu-OH)2Cl2(HOMe)(H(4)L(5))] have also been prepared, although in these cases the solid-state structures show that the macrocyclic ligand remains protonated at the pyrrolic nitrogen atoms, and the Ni(II) cations are therefore co-ordinated by the imine nitrogen atoms only to give an open conformation for the complex. The dicopper complex [Cu2(L(3))] was crystallised in the presence of pyridine to form the adduct [Cu2(py)(L(3))], in which, in the solid state, the pyridine ligand is bound within the binuclear molecular cleft. Reaction between H(4)L(1) and [Mn(thf){N(SiMe(3))2}2] results in clean formation of the dimanganese complex [Mn2(L(1))], which, upon crystallisation, formed the mixed-valent complex [Mn2(mu-OH)(L(1))] in which the hydroxo ligand bridges the metal centres within the molecular cleft.     

One-dimensional oxalato-bridged Cu(II), Co(II), and Zn(II) complexes with purine and adenine as terminal ligands

The reaction of nucleobases (adenine or purine) with a metallic salt in the presence of potassium oxalate in an aqueous solution yields one-dimensional complexes of formulas [M(mu-ox)(H(2)O)(pur)](n) (pur = purine, ox = oxalato ligand (2-); M = Cu(II) [1], Co(II) [2], and Zn(II) [3]), [Co(mu-ox)(H(2)O)(pur)(0.76)(ade)(0.24)](n)(4) and ([M(mu-ox)(H(2)O)(ade)].2(ade).(H(2)O))(n) (ade = adenine; M = Co(II) [5] and Zn(II) [6]). Their X-ray single-crystal structures, variable-temperature magnetic measurements, thermal behavior, and FT-IR spectroscopy are reported. The complexes 1-4 crystallize in the monoclinic space group P2(1)/a (No. 14) with similar crystallographic parameters. The compounds 5 and 6 are also isomorphous but crystallize in the triclinic space group P (No. 2). All compounds contain one-dimensional chains in which cis-[M(H(2)O)(L)](2+) units are bridged by bis-bidentate oxalato ligands with M(.)M intrachain distances in the range 5.23-5.57 A. In all cases, the metal atoms are six-coordinated by four oxalato oxygen atoms, one water molecule, and one nitrogen atom from a terminal nucleobase, building distorted octahedral MO(4)O(w)N surroundings. The purine ligand is bound to the metal atom through the most basic imidazole N9 atom in 1-4, whereas in 5 and 6 the minor groove site N3 of the adenine nucleobase is the donor atom. The crystal packing of compounds 5 and 6 shows the presence of uncoordinated adenine and water crystallization molecules. The cohesiveness of the supramolecular 3D structure of the compounds is achieved by means of an extensive network of noncovalent interactions (hydrogen bonds and pi-pi stacking interactions). Variable-temperature magnetic susceptibility measurements of the Cu(II) and Co(II) complexes in the range 2-300 K show the occurrence of antiferromagnetic intrachain interactions.     

Rational assembly of soluble copper(II) phosphonates: synthesis, structure and magnetism of molecular tetranuclear copper(II) phosphonates

The reactions of the dinuclear copper complexes [Cu(2)(L)(OAc)] [H(3)L = N,N'-(2-hydroxypropane-1,3-diyl)bis(salicylaldimine) or [Cu(2)(L')(OAc)] (H(3)L' = N,N'-(2-hydroxypropane-1,3-diyl)bis(4,5-dimethylsalicylaldimine)] with various phosphonic acids, RPO(3)H(2) (R = t-Bu, Ph, c-C(5)H(9), c-C(6)H(11) or 2,4,6-i-Pr(3)-C(6)H(2)), leads to the replacement of the acetate bridge affording tetranuclear copper(II) phosphonates, [Cu(4)(L)(2)(t-BuPO(3))](CH(3)OH)(2)(C(6)H(6)) (1), [Cu(4)(L)(2)(PhPO(3))(H(2)O)(2)(NMe(2)CHO)](H(2)O)(2) (2), [Cu(4)(L')(2)(C(5)H(9)PO(3))](CH(3)OH)(2) (3), [Cu(4)(L')(2)(C(6)H(11)PO(3)](MeOH)(4)(H(2)O)(2) (4) and [Cu(4)(L')(2)(C(30)H(46)P(2)O(5))](PhCH(3)) (5). The molecular structures of 1-4 reveal that a [RPO(3)](2-) ligand is involved in holding the four copper atoms together by a 4.211 coordination mode. In 5, an in situ formed [(RPO(2))(2)O](4-) ligand bridges two pairs of the dinuclear subunits. Magnetic studies on these complexes reveal that the phosphonate ligand is an effective conduit for magnetic interaction among the four copper centers present; a predominantly antiferromagnetic interaction is observed at low temperatures.     

Synthesis,characterization, and crystal structures of two new divalent metal complexes of N,N'-bis(phosphonomethyl)-1,10-diaza-18-crown-6: a hydrogen-bonded 1D array and a 3D network with a large channel

Reaction of N,N'-bis(phosphonomethyl)-1,10-diaza-18-crown-6 (H(4)L) with copper(II) acetate in 1:1 ethanol/water mixed solvents afforded a new crystal-engineered supramolecular metal phosphonate, Cu(H(2)L) (complex 1). By reaction of the same ligand with cadmium(II) nitrate in a 2:1 (M/L) ratio in methanol, a cadmium(II) complex with a 3D network structure was isolated, Cd(2.75)(L)(H(2)O)(7) x 1.5NO(3) x 7H(2)O x MeOH (complex 2). The copper(II) complex crystallized in the monoclinic space group P2(1)/c, with a =10.125(4), b = 14.103(6), and c = 14.537(6) A, beta = 91.049(8) degrees, V = 2075.4(16) A(3), and Z = 2. The Cu(II) ions in complex 1 are 6-coordinated by two phosphonate oxygen atoms, two nitrogen, and two oxygen atoms from the crown ether ring. Their coordination geometry can be described as Jahn-Teller-distorted octahedral, with elongated Cu-O(crown) distances (2.634(4) and 2.671(4) A for Cu(1) and Cu(2), respectively). The other two crown oxygen atoms remain uncoordinated. Neighboring two Cu(H(2)L) units are further interlinked via a pair of strong hydrogen bonds between uncoordinated phosphonate oxygen atoms, resulting in a one-dimensional supramolecular array along the a axis. The cadmium(II) complex is tetragonal, P4(2)/n (No. 86) with a = 20.8150(9) and c = 18.5846(12) A, V = 8052.0(7) A(3), and Z = 8. Among four cadmium(II) atoms in an asymmetric unit, one is 8-coordinated by four chelating phosphonate groups, the second one is 8-coordinated by 6 coordination atoms from a crown ring and two oxygen atoms from two phosphonate groups, the third Cd(II) atom is octahedrally coordinated by three aqua ligands and three phosphonate oxygen atoms from three phosphonate groups, and the fourth one is 6-coordinated by four aqua ligands and two oxygen atoms from two phosphonate groups in a distorted octahedral geometry. These cadmium atoms are interconnected by bridging phosphonate tetrahedra in such a way as to form large channels along the c direction, in which the lattice water molecules, methanol solvent, and nitrate anions reside. The effect of extent of deprotonation of phosphonic acids on the type of complex formed is also discussed.     

1,2,4-Triazole functionalized adamantanes: a new library of polydentate tectons for designing structures of coordination polymers

A series of functionalized adamantanes: 1,3-bis(1,2,4-triazol-4-yl)(tr(2)ad); 1,3,5-tris(1,2,4-triazol-4-yl)-(tr(3)ad); 1,3,5,7-tetrakis(1,2,4-triazol-4-yl)adamantanes (tr(4)ad) and 3,5,7-tris(1,2,4-triazol-4-yl)-1-azaadamantane (tr(3)ada) were developed as a new family of geometrically rigid polydentate tectons for supramolecular synthesis of framework solids. The coordination compounds were prepared under hydrothermal conditions; their structures reveal a special potential of the triazolyl adamantanes for the generation of highly-connected and open frameworks as well as structures based upon polynuclear metal clusters assembled with short-distance N(1),N(2)-triazole bridges. Complexes [Cd{L}(2)]A·nH(2)O [L = tr(3)ad, A = 2NO(3)(-) (4), CdCl(4)(2-) (5); L = tr(3)ada, A = CdI(4)(2-) (7)] are isomorphous and adopt a layered 3,6-connected structure of CdI(2) type. [{Cu(3)(OH)}(2)(SO(4))(5)(H(2)O)(2){tr(3)ad}(3)]·26H(2)O (6) is a layered polymer based upon Cu(3)(μ(3)-OH) nodes and trigonal tr(3)ad links. In [Cu(3)(OH)(2){tr(3)ada}(2)(H(2)O)(4)](ClO(4))(4) (8), [Cu(2){tr(3)ada}(2)(H(2)O)(3)](SO(4))(2)·7H(2)O (9) and [Cd(2){tr(3)ada}(3)]Cl(4)·28H(2)O (10) (UCl(3)-type net) the organic tripodal ligands bridge polynuclear metal clusters. Complexes [Ag{tr(4)ad}]NO(3)·3.5H(2)O (11) and [Cu{tr(4)ad}(H(2)O)](ClO(4))(2)·3H(2)O (12) have 3D SrAl(2)-type frameworks with the metal ions and adamantane tectons as topologically equivalent tetrahedral nodes, while in [Cd(3)Cl(6){tr(4)ad}(2)]·9H(2)O (13) the ligands bridge trinuclear six-connected Cd(3)Cl(6)(μ-tr)(4)(tr)(2) clusters. In the compounds [Cd(2){tr(2)ad}(4)(H(2)O)(4)](CdBr(4))(2)·2H(2)O (2) and [Cd{tr(2)ad}(4){CdI(3)}(2)]·4H(2)O (3) the bitopic ligands provide simple links between the metal ions, while in [Ag(2){tr(2)ad}(2)](NO(3))(2)·2H(2)O (1) the ligand is tetradentate and generates a 3D framework.