Phosphonate Clusters Research Articles

Iron phosphonate clusters: From magnetism to biological mimics

Abstract Synthetic strategies, structural aspects, magnetic behavior and use of some model compounds to mimic biological reaction pathways of iron phosphonates are described in a nut shell in this short review.

New cobalt- and sodium-containing heteronuclear phosphonate clusters: Synthesis, structure and properties

New polynuclear heteroligand complexes [(η-HPiv)2(μ2-Hmhp)4Na6Co5(μ6,η2-O3PPh)2(μ3,η2-Piv)2(μ3-Piv)3(μ-Piv)7]·2C10H22 (1·2C10H22) and [(η-H2O)4Na12Co12(μ5,η2-O3PPh)4(μ6-O3PPh)4(μ3,η2-mhp)8(μ2-Piv)4(μ3-Piv)8]·1.25C10H22 (2·1.25C10H22), where Hmhp is 6-methyl-2-pyridone, mhp is the 6-methyl-2-piridonate, and Piv is the pivalate anion, were obtained by the self-assembly of {Co(Piv)2}n, Na2O3PPh, and Hmhp in boiling decane (174°C). The structures of compounds 1·2C10H22 and 2·1.25C10H22 were determined by single-crystal X-ray diffraction. The magnetic properties of these compounds and their thermal decomposition were investigated. The removal of coordinated water molecules from complex 2·1.25C10H22 begins at 470°С.

Pseudopolymorphism deriving from variable π⋯π stacking modes: Discrete tetranuclear cadmium(II) phosphonate clusters with 1,10-phenanthroline as auxiliary ligand

Hydrothermal reactions of Cd(ClO 4) 2 or CdSO 4 with [(dibenzylamino)-methyl]-phosphonic acid (H 2L) as well as 1,10-phenanthroline (phen) afforded two tetranuclear cadmium(II) phosphonate cluster compounds with the formula of [Cd 4(L) 4(phen) 4]· nH 2O ( n = 4 or 6). The two compounds are supramolecular pseudoisomers which derive from two different π⋯π stacking modes of the 1,10-phenanthroline ligands in them, and such supramolecular isomerism is induced by the distinct counter-ions of the starting cadmium source.

Phosphonates as ligands in Co–Cr heterometallic clusters

Two new Co(ii)-Cr(iii) phosphonate clusters with [Co(II)(4)Cr(III)(4)] and [Co(II)(8)Cr(III)(4)] cores have been synthesized by a displacement reaction from a pre-formed heterometallic carboxylate cage. Magnetic studies show overall antiferromagnetic interactions are present in these clusters.

Phosphonate supported assembly of nanoscale lotus-leaf-shaped nonanuclear lanthanide clusters

Abstract Two discrete nonanuclear Ln(III) phosphonate clusters, formulated as, [Ln9(OH)(Hpmp)12(ClO4)(H2O)26](ClO4)13 · 18H2O (Ln = Nd for 1 and Pr for 2), were synthesized via the assembly of Ln(ClO4)3 with N-piperidinomethane-1-phosphonic acid (H2pmp) at a pH of 6.2 in aqueous solution. Single crystal X-ray diffraction and powder XRD patterns revealed that they are isostructural. In the crystal structure, the shape of arrangement of the nine Ln(III) ions can be described as a lotus-leaf. Furthermore, temperature-dependent magnetic susceptibilities of 1 and 2 have been investigated.

Mixed-valent manganese phosphonate clusters prepared under microwave-assisted and ambient conditions

Mixed-valent manganese phosphonate clusters [Mn(II)(8)Mn(III)(2)O(2)(O(3)PC(10)H(7))(4)(C(6)H(5)CO(2))(10)(py)(4)(H(2)O)(2)] (1) and [Mn(II)(4)Mn(III)(9)O(4)(OH)(2)(O(3)PC(10)H(7))(10)(C(6)H(5)CO(2))(5)(py)(8)(H(2)O)(6)] (2) are reported. Compound 1 is the first example of manganese phosphonate clusters prepared through a microwave-assisted technique. While compound 2 is obtained under ambient condition, and exhibits slow magnetic relaxation behaviour at low temperature.

Solvothermal Synthesis and Characterization of Two High-Nuclearity Mixed-Valent Manganese Phosphonate Clusters

Two novel mixed-valent manganese (Mn(II)/Mn(III)) cluster compounds were synthesized in solvothermal reactions and characterized by single-crystal X-ray diffraction, bond valence sum calculations, IR spectra, elemental analysis, and magnetic measurements. Compound 1 is a Mn 19 cluster with a cylindrical core structure. Compound 2 possess a Mn 16 core where all of the manganese sites have unique ligation environments. The magnetic measurements on both compounds indicate dominant antiferromagnetic interactions between the metal centers.

Zinc(II) Phosphonate Cage Compounds Derived from Zn6(Zn)L6 Centered Octahedral Cores

Three zinc(II) phosphonate cluster compounds have been hydrothermally synthesized and structurally characterized. Compound 1 consists of a centered {Zn6(Zn)L6}4− core and two {Zn(Phen)2(H2O)2}2+ countercations (L = N-(phosphonomethyl)pipecolinic acid, O3PCH2−NC5H9−CO2). The {Zn6(Zn)L6}4− core in compound 2 or 3 is covalently bonded to two Zn(H2O)42+ or {Zn(2,2′-bipy)(H2O)3}2+ cations through the coordination of two additional carboxylate oxygen atoms to form a nonanuclear cluster.

Synthesis and characterization of nona- and trideca-nuclear manganese phosphonate clusters

Two new Mn(III) complexes with unprecedented topologies containing the tert-butylphosphonate ligand (t-BuPO3(2-)), [Mn9O6(t-BuPO3)2(O2CMe)11 (MeCOOH)(H2O)].8H2O(1), and [NBu(n)4][Mn13O6(t-BuPO3)10(OH)2(N3)6(MeCOOH)2(H2O)2].6H2O(2) have been prepared by treatment of Mn(O2CMe)2 and NBu(n)4MnO4 with tert-butylphosphonic acid in the presence of different bases. The core of 1 consists of two [Mn3O] units connected to a near linear [Mn3] unit by four mu3-O, while the core of 2 possesses a Mn centred disklike [Mn7O6] unit linked to six additional manganese atoms via six mu4-O. Compounds 1 and 2 are both homovalent manganese(III) cage clusters, of which the six-coordinated Mn centers are all Jahn-Teller distorted. Magnetic susceptibility measurements reveal that compounds 1 and 2 display overall ferromagnetic and antiferromagnetic interactions, respectively, between the adjacent Mn(III) ions. Both the in-phase signal chi'M T and out-of-phase signal chi"M, of the two complexes exhibit frequency-dependence below approximately 3 K.

Tridecanuclear and Docosanuclear Manganese Phosphonate Clusters with Slow Magnetic Relaxation

Two novel mixed-valent manganese phosphonate clusters [MnIIMnIII12O6(OH)6(O3PC6H11)10(py)6] (1) and [MnII4MnIII18O12(O3PC6H11)8(O2CCH3)22(H2O)6(py)2] (2) are reported in this paper. Complex 1 is the first carboxylate-free manganese phosphonate cluster. While compound 2 appears to be the largest manganese cluster thus far that contains phosphonate ligand. Both show slow magnetic relaxation behaviors.

Oxo-, Hydroxo-, and Peroxo-Bridged Fe(III) Phosphonate Cages

A series of five Fe(III) phosphonate clusters with four different topologies is reported. The choice of coligand carboxylate plays an important role in directing the structure of the molecule. [Fe9(O)4(O2CCMe3)13(C10P)3] (1) and [Fe9(O)2(OH)(CO2Ph)10(C10P)6(H2O)2](CH3CN)7 (2; camphyl phosphonic acid, C10H17PO3H2 = C10PH2) represent two unprecedented nonanuclear Fe(III) cages having Fe9O4 and Fe9(O)2(OH) core structures, respectively. Whereas [Fe6O2(O)2(O2CCMe3)8(C10P)2 (H2O)2](CH3CN)4 (3) is a peroxo-bridged hexameric compound with an Fe6(O)2(O2) core. [Fe4(O)(O2CCMe3)4(C10P)3(Py)4](CH3CN)3 (4) and [Fe4(O)(O2CPh)4(C10P)3(Py)4](Py)3(CH3CN)2 (5; Py = pyridine) represents two tetranuclear clusters with the same Fe4O core structure.

Syntheses, Characterizations, and Crystal Structures of Three New Metal Phosphonocarboxylates with a Layered and a Microporous Structure

AbstractHydrothermal reactions of N‐(phosphonomethyl)proline (H3L) with MII (M = Cd, Pb, and Zn) chlorides resulted in three new metal amino‐phosphono‐carboxylates, namely, [Cd2LCl(H2O)] (1) and [Pb2Cl2(HL)] (2) with a layered structure, and [Zn7L6][Zn(H2O)6]2·16H2O (3) featuring a microporous structure built from centered octahedral Zn6(Zn) cluster anions. The cadmium(II) ions in complex 1 are octahedrally coordinated [Cd(1)O5Cl, Cd(2)O4NCl]. These cadmium octahedra form a 1D zigzag chain along the b‐axis through edge sharing, and such chains are further interconnected via phosphonate tetrahedra to form a <002> layer. The organic rings of the ligands are orientated to the interlayer space. Complex 2 also has a layered structure, in which Pb(1) is six‐coordinated by four phosphonate oxygen atoms and two carboxylate oxygen atoms from four ligands in a distorted octahedral geometry, three Pb−O distances are relatively longer than those of the remaining ones, whereas Pb(2) is six coordinated by three phosphonate oxygen atoms and one carboxylate oxygen from four ligands as well as two chloride anions in a distorted octahedral geometry, one Pb−O bond is much longer than the remaining ones. These two different types of PbII ions are further interconnected through bridging carboxylate and phosphonate groups to form a <200> layer. Complex 3 contains a novel heptanuclear zinc phosphonate cluster anion [Zn7L6]4− and two hexahydrated zinc(II) cations as well as 16 lattice water molecules. The seven ZnII cations in an anion form an unusual centered Zn6(Zn) octahedron, packing of such cluster anions creates micropores that are occupied by the hexahydrated zinc(II) cations and lattice water molecules. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Zn6[MeN(CH2CO2)(CH2PO3)](6)(Zn)]4- anion: the first example of the oxo-bridged Zn6 octahedron with a centered Zn(II) cation.

Hydrothermal reactions of N-(phosphonomethyl)-N-methylglycine, MeN(CH(2)CO(2)H)(CH(2)PO(3)H(2)) (H(3)L), with zinc(II) acetate resulted in the formation of a novel zinc carboxylate-phosphonate, [Zn(6)L(6)(Zn)][Zn(H(2)O)(6)](2) x 22H(2)O (1). The structure of 1 contains a heptanuclear zinc phosphonate cluster anion, [Zn(6)L(6)(Zn)](4-), in which seven zinc(II) cations form an unusual Zn(6)(Zn) centered octahedron with six of its Zn(3) triangle faces each further capped by a phosphonate group. The Zn(II) cations of the Zn(6) octahedron are five-coordinated whereas the centered Zn(II) cation is octahedrally coordinated. Packing of these cluster anions creates micropores occupied by the hydrated zinc(II) cations as well as lattice water molecules. The structural skeleton of 1 is retained after the removal of the lattice water molecules.

Syntheses, characterizations, and single-crystal X-ray structures of soluble titanium alkoxide phosphonates.

Reactions of Ti(OiPr)4 with different phosphonic acids RPO3H2 (R = Ph, 4-CNPh, Me, tBu) in organic solvents have been investigated. In the presence of small amounts of water, the new molecular titanium oxide alkoxide phosphonates [Ti4(mu 3-O)(OiPr)5(mu-OiPr)3(RPO3)3].DMSO [R = Ph (1), Me (2), tBu (3), 4-CNPh (4)] were isolated. The single-crystal X-ray structure analyses of 1 and 2 revealed hexacoordinated titanium atoms and a connectivity of (111) for each phosphonate. Under rigorous exclusion of water, the reaction of Ti(OiPr)4 with tert-butylphosphonic acid in toluene gave the titanium phosphonate tetramer [Ti(OiPr)2(tBuPO3)]4 (5). A single-crystal X-ray structure analysis of 5 revealed a 5 + 1 coordination of the titanium atoms as a result of the (112) connectivity of each phosphonate; such a coordination mode has never been reported for a titanium phosphate, phosphonate, or phosphinate. Compounds 1-5 were characterized by FT-IR, 31P MAS NMR, and solution multinuclear NMR (1H, 13C(1H,) 31P(1H)) spectroscopies. 13C CP MAS NMR experiments were carried out on arylphosphonates 1 and 4. Solution NMR experiments were also used to investigate the exchange reaction between 1 and 2 and the conversion of 5 to [Ti4(mu 3-O)(OiPr)5(mu-OiPr)3(tBuPO3)3].iPrOH by partial hydrolysis in the presence of Ti(OiPr)4. The phosphonate clusters 1-5 are soluble in organic solvents and are likely intermediates in the sol-gel processing of inorganic-organic hybrids based on titanium oxide and phosphonate groups that we are currently developing.

Non-Template-Centered, Closed Tetravanadium Phosphate and Phosphonate Clusters.

Tetranuclear V(III) complexes, [HB(pz)(3)](4)V(4)(&mgr;-C(6)H(5)OPO(3))(4) (I), its acetonitrile solvate (I.4CH(3)CN), and [HB(pz)(3)](4)V(4)(&mgr;-O(2)NC(6)H(4)OPO(3))(4).4C(7)H(8).H(2)O (II), and tetranuclear vanadyl complexes, (t-Bupz)(4)V(4)O(4)(&mgr;-C(6)H(5)PO(3))(4).2H(2)O (III) and (t-Bupz)(5)V(4)O(4)(&mgr;-C(6)H(5)PO(3))(4).4CH(3)CN.0.6 H(2)O (IV), have been prepared and characterized by spectroscopic, magnetic, and electrochemical methods (pz = pyrazole, t-Bupz = tert-butylpyrazole). The use of organic solvents and bulky organic groups as ancillary ligands leads to formation of neutral species instead of the anionic clusters commonly found in the hydrothermal synthesis of vanadium organophosphate/phosphonate systems. Complexes I.4CH(3)CN and IV have also been characterized by single-crystal X-ray diffraction. Crystal data: I.4CH(3)CN, triclinic, P&onemacr;, a = 15.495(3) Å, b = 17.000(3) Å, c = 17.949(4) Å, alpha = 89.17(3) degrees, beta = 86.00(3) degrees, gamma = 78.60(3) degrees, Z = 2; IV, triclinic, P&onemacr;, a = 15.541(3) Å, b = 16.340(2) Å, c = 19.069(5) Å, alpha = 83.58(2) degrees, beta = 79.67(2) degrees, gamma = 63.68(1) degrees, Z = 2. Both are closed clusters, the core structure of the first consisting of a cubane-like arrangement of metal octahedra and phosphate tetrahedra and the core structure of the second consisting of a distorted, collapsed variant of the first. Unlike other vanadium phosphate clusters, these compounds form in the absence of a central, templating agent. As such they represent the simplest form of a closed cluster in which steric forces and cluster connectivity requirements play the primary role in organizing the cluster framework.