Tsutomu Mizuta

AN X-RAY CRYSTALLOGRAPHIC STUDY ON THE MOLECULAR STRUCTURES OF SEVEN-COORDINATE (ETHYLENEDIAMINE-N,N,N'-TRIACETATO-N'-ACETIC ACID)(AQUA)-TITANIUM(III) AND -VANADIUM(III), TIIII(H-EDTA)(H2O).H2O AND VIII(HEDTA)(H2O).H2O

Abstract The molecular structures of the title complexes,[Ti III (Hedta)(H 2 O)]·H 2 O ( I ) and [V III (Hedta)(H 2 O)]·H2O( II ) (Heda 3− = mono-protonated ethylenediamine- N,N,N′,N′ -tetraacetate) have been determined by single-crystal X-ray analyses. The crystal data are as follows: I : monoclinic, Aa, a = 13.401(1), b = 12.311(1), c = 8.552(1) A , β = 97.35(1)°, V = 1399.3(1) A 3 , Z = 4, R = 0.018 and R w =0.022; II : monoclinic, Aa, a = 13.891(1), b = 8.558(1), c = 12.135(1) A , β = 95.77(1)°, V = 1435.4(1) A 3 , Z = 4, R = 0.020 and R w = 0.028. The former complex has a seven-coordinate and approximately pentagonal-bipyramidal structure in which Hedta 3− acts as a hexadentate ligand, a proton is attached to the carbonyl oxygen atom on one of the equatorial glycine rings (G-rings), and a water molecule occupies one of the five basal coordination sites. The latter is also sevencoordinate but has a structure close to a mono-capped trigonal-prism in which Hedta 3− is also hexadentate and a water molecule caps a quadrilateral face as a seventh ligand. A structural comparison of these and other Hedta complexes with the corresponding edta complexes revealed that Hedta 3− serves well as a hexadentate ligand, for those metal ions which have a propensity to form seven-coordinate edta complexes, and that protonation takes place in most edta complexes on the carboxylate group of the more constrained equatorial glycine arm (G-ring).

The molecular structure of the trans(O5) isomer of (ethylenediamine-N,N′-diacetato-N,N′-di-3-propionato)cobaltate(III), trans(O5)-[Co(eddda)]− determined by x-ray analysis and its structural comparison with some metal(III) complexes of related ligands

Abstract The crystal structure of Na[Co(eddda)]·0.5NaClO4· 1.5H2O (eddda = ethylenediamine-N,N′-diacetate-N,N′- di-3-propionate) was determined by single crystal X-ray diffraction techniques. The crystal is monoclinic with the space group P2/c, a= 14.213(4), b=8.247(3), c=15.251(4) A, β=92.99(2)° and Z = 4. The complex anion is a trans(O5) isomer in which the cobalt(III) ion is surrounded octahedrally by the two nitrogen and four oxygen atoms of eddda with the two five-membered glycine chelate rings in trans positions. Detailed comparison of the structural parameters among trans(O5)-[M(eddda)]− (M = Co(III, Cr(III), Fe(III) and Rh(III)) and other related complexes of edta-type ligands revealed that the Co(III) and Rh(III) complexes are less distorted from a regular octahedral structure than the Cr(III) complexes and much less than the Fe(III) complexes, and that eddda encircles the M(III) ions more favorably than 1,3-pdta (1,3-propanediamine-N,N,N′,N′-tetra- acetate) and much more than edta, both of which are capable of forming five-membered glycine and five- or six-membered diamine chelate rings only.

Molecular structures of Fe(II) complexes with mono- and di-protonated ethylenediamine-N,N,N′,N′-tetraacetate (Hedta and H2edta), as determined by X-ray crystal analyses

The molecular structure of the title complexes [Fe(H2O)4][Fe(Hedta)(H2O)]2 · 4H2O (I) and [Fe(H[2edta)(H2O)] · 2H2O (II) have been determined by single-crystal X-ray analyses. The crystal data are as follows: I: monoclinic, P21/n, a = 11.794(2), b = 15.990(2), c = 9.206(2) A, β = 90.33(1)°, V = 1736.1(5) A3, Z = 2 and R = 0.030; II: monoclinic, C2/c, a = 11.074(2), b = 9.856(2), c = 14.399(2) A, β = 95.86(1)°, V = 1563.3(4) A3, Z = 4 and R = 0.025. I is found to be isomorphous with the MnII analog reported earlier and to contain a seven-coordinate and approximately pentagonal-bipyramidal (PB) [FeII(Hedta)(H2O]− unit in which Hedta acts as a hexadentate ligand. The [FeII(H2edta)(H2O)] unit in II has also a seven-coordinate PB structure with the two protonated equatorial glycine arms both remaining coordinated, and thus bears a structural resemblance to the seven-coordinate [CoII(H2edta)(H2O)] reported previously.

The ligand field stabilization effect on the metal-ligand bond distances in octahedral metal complexes with edta-type ligands. Redetermination of the molecular structure of (ethylenediaminetriacetatoacetic acid)-(aqua)iron(III), [Fe(Hedta)(H2O)]

The molecular structure of the title complex [Fe(Hedta)(H2O)] (Hedta=mono-protonated ethylene- diamine-N,N,N′,N′-tetraacetate) has been redetermined by single crystal X-ray diffraction methods. The crystal data are as follows: monoclinic, space group P21/c, a=8.031(2), b=8.897(2), c=17.627(4) A, β=99.55(2)°, Z=4 and R=0.041. The complex has an octahedral structure in which the protonated edta serves as a pentadentate ligand and a water molecule completes the six coordination, the ML bond distances and LML′ bond angles redetermined are both comparable to those reported earlier, but the equatorial MO bonds trans to the MN bonds are shorter on average than the axial MO bonds, at variance with the results of the earlier structure analysis in which the R value converged to 0.12. Detailed comparison of the ML bond distances among several octahedral metal complexes with edta-type ligands including Hedta, demonstrates that the equatorial MO bonds are longer on average than the axial odes for the Cr(III), Co(III) and Rh(III) complexes to which the ligand field stabilization (LFS) contributes greatly, while the reverse holds not only for the Fe(III) complexes but also for [Al(edta)]−, [Zn(edta)]2−, [Ga(Hedta)(H2O)] and [Ge(Hedta)(OH)] to which there is no appreciable LFS contribution. The variation of the ML bond distances with the M ion in these complexes has been discussed in relation to the LFS of the M ion.

The molecular structure of sodium (aqua)(ethylenediaminetetraacetato)-titanate(III) dihydrate, Na[Ti(H(2O)-(edta)]·2H2O, as determined by X-ray crystal analysis

Abstract A single-crystal X-ray analysis revealed that the Ti(III)-edta complex formulated as [Ti(H2O)(edta)]− has a seven-coordinate and distorted pentagonal-bipyramidal structure in which edta serves as a hexadentate ligand and a water molecule occupies one of the five basal sites. The complex anion as a whole is very similar in structure to the corresponding seven-coordinate Ti(IV)—edta complex reported earlier, and is one of a few examples of seven-coordinate transition-metal edta complexes in which the metal ion has a non-symmetrical electronic configuration.

A novel structure of spontaneously resolved germanium(IV) complex with ethylenediaminetriacetatemonoacetic acid (Hedta)

Abstract The crystal and molecular structures of the complex formed when GeCl4 was mixed with the disodium salt of ethylenediaminetetraacetic acid (Na2H2edta) in hot water, have been determined by single crystal X-ray diffraction techniques. The crystal is monoclinic with the space group P21, a = 10.905(2), b = 9.691(2), c = 6.533(1) A, β = 99.60(1)° and Z = 2, and it is found to be spontaneously resolved. The complex has a novel composition of [Ge(OH)(Hedta)]·H2O in which edta serves as a pentadentate ligand with one acetate group protonated and freed from coordination, and with the sixth coordination site occupied by an OH− ion, forming a six-coordinate and electrically neutral complex.

Modified synthesis and supramolecular polymerization of rim-to-rim connected bisresorcinarenes.

The acid-catalyzed condensation reaction of resorcinol and bisdimethoxyacetals gave rise to rim-to-rim connected bisresorcinarenes in good yields. In the presence of ethanol, the homoditopic bisresorcinarenes assembled to form supramolecular polymers via hydrogen bonding interactions. The fibrous morphologies of the supramolecular polymers were confirmed by atomic force microscopy and scanning electron microscopy.

A transition-metal diaminophosphonate complex: synthesis and structure of [(η5-C5H5)(CO)2FeP(O)(NEt2)2]2FeCl2

Abstract (η 5 -C 5 H 5 )(CO) 2 FeCl reacts with P(OMe)(NEt 2 ) 2 in benzene to give isolable [(η 5 -C 5 H 5 )(CO) 2 FeP(OMe)(NEt 2 ) 2 ]Cl, which is converted by thermolysis into (η 5 -C 5 H 5 )(CO) 2 FeP(O)(NEt 2 ) 2 FeCl 2 , crystallizing in the monoclinic space group C 2 with a 18.700(4), b 9.065(1), c 16.608(3) A β 135.54(1)°, and Z = 4. X-Ray diffraction has revealed that the P(O)(NEt 2 ) 2 group covalently bonds to the iron atom of the (η 5 -C 5 H 5 )(CO) 2 Fe moiety through the P atom and also coordinates to FeCl 2 through the phosphoryl oxygen, and that one of the nitrogen atoms in the P(O)(NEt 2 ) 2 group has a planar geometry. (η 5 -C 5 H 5 (CO) 2 FeP(O)(NEt 2 ) 2 ] is obtained by treatment with pyridine.

Conversion of a stannylphosphenium complex into a stannylenephosphine complex of Mo and W: double bond migration from MP to MSn

Abstract Four-legged piano-stool complexes, Cp(CO)2(SnR3)M{ PN(Me)CH2CH2N Me(OMe)}, containing a stannyl group (SnPh3, SnMe3, SnnBu3) and diamino-substituted phosphite ( PN(Me)CH2CH2N Me(OMe) which is abbreviated as PNN(OMe)) were prepared for Mo and W, and the reactions of these complexes with a Lewis acid (BF3·OEt2 and TMSOTf) were examined. For the SnPh3 and SnMe3 complexes, stannylene complexes [Cp(CO)2(SnR2)M{PNN(R)}]X (X=OTf− or BF4−) were formed with migration of an R group from Sn to P. X-ray analyses of [Cp(CO)2(SnPh2)W{PNN(Ph)}]OTf and [Cp(CO)2(SnMe2)W{PNN(Me)}]OTf reveal that these complexes are regarded as stannylene tungsten complexes stabilized by an oxygen of OTf−. In the reaction of the SnnBu3 complex with TMSOTf, the corresponding stannylene complex and an unexpected neutral phosphenium complex, Cp(CO)2M{PNN}, were formed. However, when BF3·OEt2 was used in place of TMSOTf, cationic phosphenium complexes in addition to a neutral phosphenium complex were observed. In any case, an OMe anion abstraction by a Lewis acid takes place at the first stage to give a cationic phosphenium complex, and then aryl or alkyl migration takes place to give a stannylene complex. A relatively strong SnnBu bond retards the alkyl migration, resulting in the observation of the cationic phosphenium complexes.

Structure elucidation of secondary metabolites isolated from the leaves of Ixora undulate and their inhibitory activity toward advanced glycation end-products formation

Three aromatic glycosides (1-3), two sulfur and nitrogen-containing compound glucosides (4, 5), and one flavonoid glycoside (6) were isolated from the leaves of Ixora undulata. Their structures were established by extensive 1D, 2D NMR, and HRESIMS experiments, and structure 4 was further confirmed by single crystal X-ray diffraction analysis. Of the assayed compounds, 7, 11 and 12 showed strong inhibitory activity toward advanced glycation end-products formation with IC50 values of 86.0 μM, 76.6 μM and 98.6 μM, respectively.