Amir H. Mahmoudkhani

Cobalt(II), nickel(II), and zinc(II) complexes with bidentate N,N′-bis(β-phenylcinnamaldehyde)-1,2-diiminoethane Schiff base: synthesis and structures

A series of complexes of the type M(Phca2en)X2, where Phca2en� /N ,N ?-bis(b-phenyl-cinnamaldehyde)-1,2-diiminoethane, M(II) � /Co, Ni or Zn and X � /Cl, Br, I or NCS have been synthesized and characterized. The crystal and molecular structures of Co(Phca2en)Cl2 (2), Ni(Phca2en)Br2 (5) and Zn(Phca2en)Cl2 (6) were determined by X-ray crystallography from single-crystal data. Complexes 2 and 5 are isomorph and isostructure, in which the coordination polyhedron about the central metal ion is distorted tetrahedron with Cl� /Co� /Cl, 110.17(6)8 ;N � /Co � /N, 84.16(13)8 and Cl� /Zn � /Cl, 112.02(6)8 ;N � /Zn� /N, 83.45(16)8. The complex 5 crystallizes in triclinic system with two molecules per asymmetric unit, both having nickel ion in distorted tetrahedral geometry, Br � / Ni � /Br, 122.645(18)8 and 125.729(18)8 ;N � /Ni � /N, 84.63(9)8 and 85.08(9)8. These structures consist of intermolecular hydrogen bonds of the type C � /H �� � X. The formation of the C � /H ��� M weak intramolecular hydrogen bonds due to the trapping of C� /H bonds in the vicinity of the metal atoms are reported for 2, 5 and 6 .A 1 H NMR study of Zn complexes gives further evidence for the presence of such interactions and their significance. The spectral properties of the above complexes are also discussed. # 2002 Elsevier Science Ltd. All rights reserved.

Phenylphosphonic acid as a building block for two-dimensional hydrogen-bonded supramolecular arrays

Abstract The potential use of organic phosphorus acids for the architecture of supramolecular hydrogen-bonded assemblies has been demonstrated by the structural determination of phenylphosphonic acid (1), anilinium phenylphosphonate (2), p-phenylazoanilinium phenylphosphonate (3), ethylenediammonium phenylphosphonate hydrate (4) and hexamethylenediammonium phenylphosphonate hydrate (5). Compounds 1, 2, 4 and 5 exhibit layered structures with two-dimensional networks of hydrogen bonds from which the organic tails point out. Compound 3 crystallizes as two concomitant polymorphs showing supramolecular isomerism: a monoclinic phase (3a) with a layered structure and a triclinic phase (3b) in which hydrogen bonds form columns. In these assemblies, there are supramolecular motifs such as chains and rings of hydrogen-bonded moieties. Water molecules are involved in the formation of hydrogen-bonding networks for compounds 4 and 5. For compound 5, hexamethylenediammonium ions link the adjacent sheets, forming a pillared-layered structure. It has been shown that the phosphonate groups can act as both donor and acceptor of hydrogen bonds. Analysis of the hydrogen bonds of the types (P–)O–H⋯O(–P) and N–H⋯O(–P) reveals that they can be regarded as medium to strong hydrogen bonds.

Structural investigation of nickel thiolates: a cyclic hexanuclear nickel thiolate with highly distorted NiS4 units

Abstract Reaction of nickel(II) chloride with 2-trimethylsilylethanethiol in the presence of potassium hydroxide yields a dark red–brown solid material which contains hexakis[di-μ-(2-trimethylsilylethanethiolato)nickelII]. The main building block of this complex, the NiS4 unit, deviates significantly from planar geometry in comparison with other known hexanuclear cyclic nickel thiolates. The steric effect of the bulky groups at the β-position of the thiolate ligands is suggested to be responsible for a tetrahedral distortion of the NiS4 units in clusters with large rings.

A novel oligomerization versus metal chelation: synthesis and crystal structure of pentakis[di-μ-(diisopropylaminoethanethiolato)nickel]

Abstract Reaction of nickel(II) ions with diisopropylaminoethanethiolate ligands has been found to be self-assembled in the solution to obtain an unexpected pentanuclear cluster of the title compound. Characterization of the product by single-crystal X-ray crystallography revealed that it consists of a homoleptic nickel thiolate with a pentagonal-prismatic sulfur framework. An efficient method of the data collection using area detectors has also been developed for the X-ray structure determination of polynuclear metal thiolates.

Structural correlations in methylphosphonate and phosphite salts: crystal structures of anilinium and ethylenediammonium methylphosphonates

Abstract Two organic salts of methylphosphonic acid with aniline (1) and ethylenediamine (2) has been synthesized and structurally characterized using single-crystal X-ray diffraction analysis. Compound 1 exhibits a H-bonded layered structure, in which anilinium cations and methylphosphonate anions are arranged alternately at both side of H-bonded sheets. In compound 2, methylphosphonic acid is deprotonated to form a dianion while ethylenediamine is protonated to form a dication. They are linked together via N–H⋯O–P hydrogen bonds forming a three-dimensional H-bonded network. Analysis of hydrogen bonds using graph-set theory was performed to assign supramolecular motifs. A comparison of the geometry of methylphosphonate anions with that for phosphite anions in closely related compounds, reveals the stereochemical equivalence of the (P–)H atom and (P–)CH3 group. We have also found strong structural correlations between inorganic and organic salts of methylphosphonic and phosphorus acids.

SYNTHESIS AND SPECTROSCOPIC INVESTIGATION OF 4-METHYLPHENYL ESTERS OF DIMETHYL PHOSPHORAMIDOCHLORIDIC ACID AND DIMETHYL PHOSPHORAMIDOFLUORIDIC ACID

Abstract Synthesis of 4-methylphenyl esters of N,N-dimethyl phosphoramidochloridic acid (1) and N,N-dimethyl phosphoramidofluoridic acid (2) is reported. 18-Crown-6 with potassium fluoride was found an effective reagent for the conversion of 1 to 2. These compounds were characterized by using 1H, 31P NMR, infrared and mass spectroscopic data. Analysis of the 1H NMR spectrum of ester 1 gives a long-range 31P-1H spin spin coupling (7 J P-H = 1.2 Hz). A possible explanation for this unusual seven-bond coupling is discussed. In this study, a reasonable correlation between 31P chemical shifts and P=O vibration frequencies is suggested.

A redetermination of cis-aquabis(glycinato-κ2N,O)copper(II)

The crystal structure of the title compound, [Cu(C2H4NO2)2(H2O)], reported by Freeman et al. [(1964). Acta Cryst. 17, 1463-1470], has been reinvestigated and its absolute configuration established by anomalous dispersion effects. The origin of chirality in the crystalline state of this compound is the formation of right-handed helices from a CuII coordination network self-resolved into a pure enantiomeric phase.

The lamellar architecture of 1,6-hexamethylenediammonium tetrachlorocobaltate(II)

In the title compound, (C6H18N2)[CoCl4], organic dications and inorganic dianions interact with each other through N—H⋯Cl hydrogen bonds, forming infinite two-dimensional sheets of anions parallel to the ac plane. Alkyl chains act as spacers between these sheets. Only three Cl atoms are involved in hydrogen bonding with ammonium groups. The asymmetric unit consists of one anion together with half of each of two cations on inversion centres.

Self-Assemblies of Extended Hydrogen-Bonded Arrays Using 1,4-Butanebisphosphonic Acid as a Versatile Building Block

Two organic salts of 1,4-butanebisphosphonic acid, bis(ethylenediammonium) butanebisphosphonate hydrate ( 1 ) and bis(hexamethylenediammonium) butanebisphosphonate hydrate ( 2 ), have been structurally characterized using single-crystal x-ray diffraction analyses. Compound 1 exhibits a H-bonded pillared bilayered structure, in which etheylenediammonium cation acts as a spacer between the anions resulting in the formation of two types of cavities. The larger cavity is filled by four water molecules though having hydrophobic character. Thus, the material behaves as a nanoporous organic solid. Compound 2 shows a multidimensional hydrogen bonding networks: one-dimensional arrays parallel to the b axis and two-dimensional sheets parallel to the ab plane. The N--H·;·;·;O--P hydrogen bonds, forming H-bonded supramolecular networks, are regarded to be strong and directional hydrogen bonds.

Two-Dimensional Inorganic Networks in the Crystal Structures of Calcium and Strontium Phosphite Monohydrates

Abstract The crystal structures of two layered metal phosphites M(HPO3)H2O where M = Ca and Sr are reported. These compounds are the first examples of inorganic phosphites structurally related to metal phosphonates with the general formula of M(RPO3)H2O. They crystallize in monoclinic system with space group P21/c and are isostructuml. The structures consist of two-dimensional sheets formed by linked metal and phosphorus polyhedra, which are held together by O-H…O hydrogen bonds.