Zdzisław Gałdecki

Novel polynuclear compound of europium with N-phosphonomethylglycine : spectroscopy and structure

Abstract Phosphonic acid analogues of amino acids display interesting biological activities, the possible applications of which range from medicine to agriculture. Aminophosphonates are found in tissues as free compounds but their most frequent forms of occurrence include complex structures, such as lipids, proteins and polysaccharides [1] . For the first time, to our knowledge, lanthanide compounds with N-phosphonomethylglycine were obtained and analyzed by X-ray diffraction methods. The compound is polynuclear, with unexpected architecture, and crystallizes in the P21/c space group (cell parameters a=17.788(4) A, b=10.706(2) A, c=18.560(4) A, β=113.37(3)°, Z=4). Two nonequivalent metal sites exist in the structure. Both carboxyl and phosphonate groups of the ligand are involved in metal ion coordination forming two centrosymmetric dimers: one by the carboxyl (simple and chelating) bridges, and one by phosphonate groups. Moreover, in the latter dimer, coordination of metal ion is completed by three water molecules and one oxygen of perchlorate ion, thus the coordination number is 8. In the former dimer, additional water molecules are bonded and the coordination number of Eu becomes 9, with a little different distortion. The M–M distances are 4.012 and 5.940 A for carboxyl and phosphonic dimers, respectively. The compound was characterized by IR and electron spectroscopy methods. Absorption, excitation and emission spectra were measured down to 77 K. Electron transition probabilities and splitting of levels were analyzed and compared to the structural data. Assignment of the vibronic components in electronic transitions, which obey the selection rule ΔJ=0.2 was made on the basis of IR spectra.

New water-soluble rhodium(I) complexes containing 1-methyl-1-azonia-3,5-diaza-7-phosphaadamantane iodide

Reaction of [Rh2Cl2(CO)4] with stoichiometric quantities of 1-methyl-1-azonia-3,5-diaza-7-phosphaadamantane iodide (mtpa+I-) in MeOH and H2O yields square-planar [RhI(CO)(mtpa+I-)2] 1 and trigonal-bipyramidal [RhI(CO)(mtpa+I-)3]·4H2O 2, respectively. The complexes are stable in aqueous solution under inert atmosphere and catalyse the hydroformylation and the hydrocarboxylation of alkenes and the hydrogenation of aldehydes and alkenes. An X-ray crystallography study revealed that 2 has a TBPY-5 structure. The coordination around the Rh atom forms a nearly ideal trigonal bipyramid [a=15.705(3) A, b=13.219(3) A, c=20.894(4) A, monoclinic, space group P21/c, Z=4, β=110.72(3)°].

Structural, spectroscopic and catalytic properties of water-soluble hydride rhodium complexes [RhH(Rtpa+I−)4]H2O (R=Me, Et)

Abstract New rhodium(I) hydrido complexes [RhH(mtpa+I−)4]·H2O (1) and [RhH(etpa+I−)4]·H2O (2) (where mtpa+I−=1-methyl-1-azonia-3,5-diaza-7-phosphatricyclo[3.3.1.13,7]decane iodide, etpa+I−=1-ethyl-1-azonia-3,5-diaza-7-phosphatricyclo[3.3.1.13,7]decane iodide) have been synthesized and characterized using 1H, 31P NMR and IR spectra and X-ray crystallography. Both complexes have the trigonal-bipyramidal structure. The 1H NMR spectra indicate that in solutions the complexes have fluxional properties. The compounds are very stable in water under neutral atmosphere. They are efficient catalysts of hydrogenation of CC bonds in two-phase catalytic systems.

CARBONYL RUTHENIUM(III) COMPLEXES WITH 1,10-PHENANTHROLINE AND 2,2'-BIPYRIDINE

Abstract The reaction of ruthenium trichloride with 1,10-phenanthroline or 2,2′-bipyridine in formic acid leads to the formation of ruthenium(III) carbonyl complexes: [RuCl3(CO)(phen)], 1, and [RuCl3(CO)(bpy)], 2. The crystal structures of the complexes have been determined by single-crystal X-ray analysis. Both complexes have distorted octahedral structures with CO ligands in the trans coordination site relative to the nitrogen atom. The EPR spectra of complexes 1 and 2 dissolved in DMF have been investigated. For both compounds a hyperfine structure has been observed for g3 in the spectra.

Synthesis, reactivity and structure of [Ir4(μ-CO)3(CO)5(μ-PPh2pyl)(PPh2pyl)2]

Abstract Ir( 4 (CO) 12 reacts with P(Ph 2 pyl) 3 giving [Ir 4 (μ-CO) 3 (CO) 5 (μ-PPh 2 pyl)(PPh 2 pyl) 2 ] containing one phosphine bridging ligand coordinating via P and N atoms and [Ir 4 (μ-CO) 3 (CO) 6 (PPh 2 pyl) 3 ] which in solution is at equilibrium with the former cluster.

Structure and properties of di-μ-acetato-dichlorobis(2,2′-bipyridine)dirhodium(II)-trihydrate

Reduction of [Rh2(μ-OAc)2(bpy)2(H2O)2](OAc)2 and [Rh2Cl2(μ-OAc)2(bpy)2] · 3H2O complexes with ethanol and [Cr2(OAc)4(H2O)2] has been investigated using e.p.r. and u.v.–vis. spectra. The results indicate that stable complexes containing the [Rh23+] entity are not formed. The X-ray structure of [Rh2Cl2(μ-OAc)2(bpy)2] · 3H2O has been determined. Coordination around the Rh atom is in the form of a distorted octahedron. The complex shows an almost ideal eclipsed conformation. The equatorial coordination sites are occupied by bridging carboxylato ligands and 2,2′-bipyridine and axial positions by the Cl ligand and the rhodium atom. The Rh–Rh distance is 2.574 Å.

Infinite sheet structure of disodium tetra-μ-acetato- dichlorodirhodate(II) tetrahydrate

The binuclear rhodium(II) complex Na2[Rh2Cl2(OAc)4]· 4H2O has an infinite sheet structure. Binuclear anionic complexes [Rh2Cl2(OAc)4]2− are bound with cationic entities. The Na+ cation has pseudooctahedral coordination and is surrounded by two chloro ligands and two oxygen atoms of bridging acetato ligands of two [Rh2Cl2(OAc)4]2− anions and two water molecules. Both Cl and H2O are bridging ligands involved in formation of the Na+ chains. The remaining water molecules are located between sheets.

Structure of two novel binuclear complexes of EuIII containing bridging DL- and L-α-alaninehydroxamic acids

Two novel binuclear complexes of EuIII with bridging DL- and L-α-alaninehydroxamic acids of the formulae [Eu(DL-α-Alaha)(H2O)6]2(ClO4)6 and [Eu(L-α-AlahaH)(H2O)6]2(ClO4)8 (further denoted as 1 and 2) were synthesized from an aqueous solution at pH≈4.5. Their crystal structures were determined by X-ray diffraction with the final R=0.036 and 0.043 for compounds 1 and 2, respectively. The structures were solved by direct methods and refined by full-matrix least-squares using SHELXTL-PC programs, on 4332F0 values for complex 1 and 5728 for complex 2, with anisotropic temperature factors for the non-hydrogen atoms. Positions of hydrogen atoms were taken from the ΔF synthesis and refined with isotropic temperature factors. The title compounds crystallize in the P21/n (1) and C2 (2) space groups, with the unit cell parameters as follows: 1 a=10.347(1), b=11.289(2), c=16.968(3) A, β=95.37(1)°; 2 a=19.912(3), b=8.620(2), c=15.881(3) A, β=107.37(3)°. The two structures consist of dimer units formed by two NO bridging groups of the aminohydroxamic acid molecules. In addition, the two metal ions are chelated by the CO and NO groups, forming five-membered rings. The bridging oxygen atoms in the complexes are not the carbonyl oxygens but rather the hydroxamic ones. Centrosymmetric dimers are formed in compound 1, whereas in the case of the compound with the L-handed ligand the dimer possesses twofold axes. Additionally, two molecules of HClO4 are present in the structure of 2. Hydrogen bonds are created between N and O sites of the ligands (Alaha, H2O molecules). A structural effect of the ligand chirality was found and the Eu–Eua distances were determined: these are equal to 4.114 and 4.079 Afor compounds 1 and 2, respectively. These results are, to our knowledge, the first ones obtained for lanthanide complexes with aminohydroxamic acids from X-ray data.

Molecular modeling and X-ray analysis for a structure–taste study of α-arylsulfonylalkanoic acids

Abstract Molecular modeling and X-ray analysis have been used to study the sweet taste chemoreception of α-arylsulfonylalkanoic acids. It has been found that the 3D model builder CORINA provides structures capable of discriminating active and inactive compounds. These structures, however, do not necessarily comply with the global minima resulting from a conformational search using the MM + force field. The self-organizing neural network mapping used to simulate the glucophore–receptor interactions indicates that a synclinal conformation is probably the active one.

Molecular structure and properties of the rhodium(II) complexes with chemilabile ether–phosphine ligands P(2-MeOC6H4)3 and P(2,6-(MeO)2C6H3)3

Abstract Reactions of dirhodium tetraacetate [Rh2(O2CCH3)4] with tris(2-methoxyphenyl)phosphine (OMP) yield the oxygen-metallated complexes [Rh2(μ-OAc)3{μ-(2-OC6H4)P(2-MeOC6H4)2}(HOAc)] (1·HOAc) and [Rh2(μ-OAc)3{μ-(2-OC6H4)P(2-MeOC6H4)2}(NCMe)] (1·NCMe). In the case of tris(2,6-dimethoxyphenyl)phosphine (DOMP) analogous compound [Rh2(μ-OAc)3{μ-(2-O-(6-MeO)C6H3)P(2,6-(MeO)2C6H3)2}(HOAc)] (2·HOAc) was obtained. In both ligands the CH3+ cation of one of the methoxy substituents is split off and the phosphine replaces one of the acetato bridges to form the bridge with Rh24+ core closing the six-member ring via P and O atoms. The compounds have been characterized using UV–vis, IR, 1H-, 13C{1H}- and 31P{1H}-NMR spectroscopies. The crystal structure of compound 1·NCMe has been determined. The Rh(1)Rh(2) distance is distinctly longer than that in [Rh2(OAc)4(H2O)2] (3·2H2O). Axial sites of dirhodium core are occupied by a molecule of acetonitrile and a methoxy group of one of the nonmetallated phenyl rings. Detailed NMR studies reveal dynamic properties of complex 1 involving exchange between axial methoxy substituents and tilting of the metallated ring. The complexes 1 and 2 react with carbon monoxide giving complexes with a CO ligand coordinated in axial coordination sites.