Structural variations in layered alkaline earth metal cyclohexyl phosphonates

Two series of alkaline earth metal cyclohexyl phosphonates, M(C6H11PO3H)2(H2O) (M = Ca, Sr and Ba) (1-3) and M(C6H11PO3)(H2O) (M = Mg, Ca, Sr, and Ba) (4-7) have been synthesized under mild reaction conditions. All new compounds have been characterized using elemental analysis, IR, TGA and powder X-ray diffraction techniques. The molecular structure of compound 2 determined using single crystal X-ray diffraction technique reveals a layered polymeric structure

Microwave assisted solid-state synthesis of functional organotin carboxylates from sterically encumbered 3,5-di-tert-butylsalicylic acid

Microwave assisted solid-state reaction between equimolar quantities of sterically encumbered 3,5-di-tert-butylsalicylic acid (H2-DTBSA) and n-butylstannoic acid results in the formation of hexameric drum shaped stannoxane [nBuSn(O)(H-DTBSA)]6 (1). Synthesis of 1 could not be achieved under normal thermal conditions or mechanical grinding. However, the azeotropic removal of water produced in the reaction of nBu2SnO with 3,5-di-tert-butyl salicylic acid in benzene yielded the tetrameric ladder shaped stannoxane [{nBu2Sn(H-DTBSA)}2O]2 (2), which could also be synthesized in better yields by microwave irradiation as in the case of 1. Compounds 1 and 2 have been characterized by elemental analysis, IR, MALDI-MS and NMR (1H and 13C) spectroscopy. The structures of compound 1 and 2 are determined by single crystal X-ray diffraction techniques. Compound 1 is hexameric with a Sn6O6 drum core while compound 2 forms a ladder structure with three Sn2O2 rings, both decorated with –OH functionalities on the exterior of the polyhedral structure. While the formation of 1 from n-butylstannoic acid is straightforward, the formation of 2 from nBu2SnO (and not a cyclic structure similar to 3, where the phenolic oxygen also coordinates to tin) can be understood in terms of the increased steric hindrance in DTBSA for the phenolic protons to react with tin.© Elsevie

Microwave assisted solid-state synthesis of functional organotin carboxylates from sterically encumbered 3,5-di-tert-butylsalicylic acid

Microwave assisted solid-state reaction between equimolar quantities of sterically encumbered 3,5-di-tert-butylsalicylic acid (H2-DTBSA) and n-butylstannoic acid results in the formation of hexameric drum shaped stannoxane [nBuSn(O)(H-DTBSA)]6 (1). Synthesis of 1 could not be achieved under normal thermal conditions or mechanical grinding. However, the azeotropic removal of water produced in the reaction of nBu2SnO with 3,5-di-tert-butyl salicylic acid in benzene yielded the tetrameric ladder shaped stannoxane [{nBu2Sn(H-DTBSA)}2O]2 (2), which could also be synthesized in better yields by microwave irradiation as in the case of 1. Compounds 1 and 2 have been characterized by elemental analysis, IR, MALDI-MS and NMR (1H and 13C) spectroscopy. The structures of compound 1 and 2 are determined by single crystal X-ray diffraction techniques. Compound 1 is hexameric with a Sn6O6 drum core while compound 2 forms a ladder structure with three Sn2O2 rings, both decorated with –OH functionalities on the exterior of the polyhedral structure. While the formation of 1 from n-butylstannoic acid is straightforward, the formation of 2 from nBu2SnO (and not a cyclic structure similar to 3, where the phenolic oxygen also coordinates to tin) can be understood in terms of the increased steric hindrance in DTBSA for the phenolic protons to react with tin.© Elsevie

A hexanuclear iron(III) complex [Fe6O2(OH)2(PhCOO)10(hedmp)2] . 3CH3CN assembled from 2-hydroxyethyl-3,5-dimethyl pyrazole

In order to assemble polynuclear iron(III) complexes, the coordination chemistry of the 2-hydroxyethyl- 3,5-dimethylpyrazole (hedmp-H) ligand has been investigated. Reaction of hedmp-H with trinuclear iron carboxylate precursor [Fe3O(PhCOO)6(H2O)3]Cl in acetonitrile yielded the hexanuclear Fe(III) complex [Fe6O2(OH)2(PhCOO)10(hedmp)2].3CH3CN (1). This aggregate has been characterized by employing various analytical techniques, spectroscopic studies and single crystal X-ray diffraction. Detailed magnetic susceptibility measurements revealed that 1 displays an ST = 5 ground state

Synthesis and characterization of new complexes formed by insertion of carbon disulphide in RuL₃Cl3 (L=PPh₃ and AsPh₃)

1113-1115Reaction of RuL₃Cl₃ (L=PPh₃ and AsPh₃) with stoichiometric amount of CS₂ in ethanol-dichloromethane mixed solvent systems at room temperature yields paramagnetic complexes of the type [RuL₂Cl₂(S₂COEt)].The complexes have been characterized by conductance, IR, electronic, ESR spectral, magnetic moment measurement and thermal data as well as by elemental analysis. The appearance of three g-values in the ESR spectra reveal a highly distorted octahedral environment around ruthenium(III) ion with one bidented EtOCS₂⁻ ligand

Noncovalent synthesis of hierarchical zinc phosphates from a single Zn<SUB>4</SUB>O<SUB>12</SUB>P<SUB>4</SUB> double-four-ring building block: dimensionality control through the choice of auxiliary ligands

In contrast to the well-known reaction of phosphonic acids RP(O)(OH)2 with divalent transition-metal ions that yields layered metal phosphonates [RPO3M(H2O)]n, the 2,6-diisopropylphenyl ester of phosphoric acid, dippH2, reacts with zinc acetate in methanol under ambient conditions to afford tetrameric zinc phosphate [(ArO)PO3Zn(MeOH)]4 (1). The coordinated methanol in 1 can be readily exchanged by stronger Lewis basic ligands at room temperature. This strategy opens up a new avenue for building double-four-ring (D4R) cubane-based supramolecular assemblies through strong intercubane hydrogen-bonding interactions. Seventeen pyridinic ligands have been used to synthesize as many D4R cubanes [(ArO)PO3Zn(L)]4 (2-18) from 1. The ligands have been chosen in such a way that the majority of them contain an additional functional group that could be used for noncovalent synthesis of extended structures. When the ligand does not contain any other hydrogen-bonding donor-acceptor sites (e.g., 2,4,6-trimethylpyridine (collidine)), zero-dimensional D4R cubanes have been obtained. The use of pyridine, lutidine, 2-aminopyridine, and 2,6-diaminopyridine, however, results in the formation of linear or zigzag one-dimensional assemblies of D4R cubanes through strong intermolecular C=H&#183;&#183;&#183;O or N=H&#183;&#183;&#183;O interactions. Construction of two-dimensional assemblies of zinc phosphates has been achieved by employing 2-hydroxypyridine or 2-methylimidazole as the exo-cubane ligand on zinc centers. The introduction of an alcohol side chain on the pyridinic ligand in such a way that the =CH2OH group cannot participate in intracubane hydrogen bonding (e.g., pyridine-3-methanol, pyridine-4-methanol, and 3,5-dimethylpyrazole-N-ethanol) leads to the facile noncovalent synthesis of three-dimensional framework structures. Apart from being useful as building blocks for noncovalent synthesis of zeolite-like materials, compounds 1-18 can also be thermolyzed at approximately 500 &#176;C to yield high-purity zinc pyrophosphate (Zn2P2O7) ceramic material

Nuclearity control in molecular iron phosphates through choice of iron precursors and ancillary ligands

One to five, one at a time: The choice of iron precursors and the amine co-ligand are employed as switches to control the nuclearity in iron phosphate molecular clusters. Using this control, it is possible to isolate selectively either a mono, di, tri, tetra, or pentanuclear cluster, for a given set of reactants. The potential of a mono-organophosphate ester in assembling low to medium nuclearity iron complexes with novel topological architectures has been investigated. Reaction of 2,6-diisopropylphenyl dihydrogen phosphate (dipp-H2) with ferrous acetate under an inert atmosphere resulted in the formation of mononuclear, [Fe||(dipp-H)2(py)4] (1) (py=pyridine), dinuclear [Fe|||2O(dipp-H)4(3,5-dmpz)3(thf)]&#183;(3,5-dmpz)(thf)3 (2) (3,5-dmpz=3,5-dimethylpyrazole, thf=tetrahydrofuran), and trinuclear [Fe|||2Fe||O(dipp-H)6(thf)3]&#183;(collidine) (3) complexes by changing the ancillary amine used in the reaction. Use of a preformed &#956;3-oxo bridged trinuclear complex, [Fe|||3O(O2CR)6(H2O)3]X (X=Cl and NO3), as the precursor yielded two tetranuclear iron phosphates, [Fe|||4O(dipp)3(py)4(PhCOO)4]&#183;(toluene)3 (4) and [FeIII4O(dipp)3(OAc)4(py)4]&#183;(py)2 (5), having a core structure similar to those found in tetranuclear iron phosphonates. When FeCl3&#183;6H2O was used as the iron precursor, an unprecedented pentanuclear iron phosphate complex, [Fe|||5O(dipp)6(py)4Cl2][pyH] (6) with a novel structure was isolated. Another pentanuclear complex having a similar core structure, [Fe5O(dipp)6(HO2CPh)3(CH3CN)3Cl] (7) was isolated on treatment of dipp-H2 with the triangular complex, [Fe|||3O(O2CPh)6(H2O)3]Cl in the absence of any added amine co-ligand. Compounds 1-7 have been characterized by analytical techniques, spectroscopic studies, single crystal X-ray diffraction studies, and magnetic measurements. The Mössbauer studies carried out at room temperature support the formulation of all the compounds

Heptacoordinated Nickel(II) as an Ising-Type Anisotropic Building Unit: Illustration with a Pentanuclear [(NiL)₃{W(CN)₈}₂] Complex

Heptacoordinated nickel­(II) complexes characterized by substantial Ising-type single-ion anisotropy have been involved in the construction of two pentanuclear [Ni₃W₂] compounds by association with [W­(CN)₈]^3–. For one of them, slow relaxation of magnetization was observed to occur concomitantly with antiferromagnetic ordering

Heptacoordinated Nickel(II) as an Ising-Type Anisotropic Building Unit: Illustration with a Pentanuclear [(NiL)₃{W(CN)₈}₂] Complex

Heptacoordinated nickel­(II) complexes characterized by substantial Ising-type single-ion anisotropy have been involved in the construction of two pentanuclear [Ni₃W₂] compounds by association with [W­(CN)₈]^3–. For one of them, slow relaxation of magnetization was observed to occur concomitantly with antiferromagnetic ordering

Single-ion magnet behaviour of heptacoordinated Fe(II) complexes: on the importance of supramolecular organization

Supramolecular organization of a metal complex may significantly contribute to the magnetization dynamics of mononuclear SMMs. This is illustrated for a heptacoordinated Fe(II) complex with rather moderate Ising-type anisotropy for which a slow magnetization relaxation with significant energy barrier was reached when this complex was properly organized in the crystal lattice. Incidentally, it is the first example of single-ion magnet behaviour of Fe(II) in a pentagonal bipyramid surrounding