Bo-Mu Wu

Sesquiterpene lactones from Elephantopus scaber

Abstract The whole plant of Elephantopus scaber afforded the known deoxyelephantopin and isodeoxy-elephantopin, and a new germacranolide sesquiterpene lactone named scabertopin, whose structure and stereo-chemistry were determined by spectroscopic methods and single-crystal X-ray analysis.

A structural and electrochemical study of some oxovanadium(IV) heterochelate complexes

Abstract Physicochemical studies on two oxovanadium(IV) heterochelates involving the biologically active ONO donor ligand, dipicolinic acid (DPA) is reported. Structure of the complex [VO(DPA)(ophen)] · 3H2O has been determined and this led to the understanding of the geometry of the donor sites around the oxovanadium(IV) centre of other related complexes. Electrochemical behavior of the complexes were explored by cyclic voltammetry.

Coordination chemistry of organometallic polydentate ligands. syntheses of Fe-M complexes using Fe(CO)4(Ph2Ppy-P)[Ph2Ppy = 2-(Diphenylphosphino)Pyridine] and TRANS-Fe(PhPMepy)2(CO)3[PhPMepy = 2-(Phenylmethylphosphino) Pyridine] AS A Neutral BI- OR Tridentate Ligand

Abstract Fe(CO) 4 (Ph 2 Ppy-P) (1), prepared by the oxygen-atom transfer reaction, reacted as an organometallic bidentate ligand with HgX 2 (X = Cl, I) to form binuclear complexes containing a Fe—Hg bond and treatment of the organometallic tridentate ligand trans-Fe (PhPMepy) 2 (CO) 3 (2) with M(CO) 6 (M = Cr, Mo), M(SCN) 2 (M = Zn, Cd, Co, Ni, Mo), HgX 2 (X = Cl, I) and CdCl 2 also afforded binuclear complexes including a Fe—M bond. The crystal and molecular structures of the Fe-Hg complexes (CO) 4 Fe(μ-Ph 2 Ppy)Hg(μ-Cl) 2 HgCl 2 (3), (CO) 3 Fe(μ-PhPMepy) 2 Hg(μ-Cl) 2 HgCl 2 ·1/2CH 2 Cl 2 (5) and (CO) 3 Fe(μ-PhPMepy) 2 Hg(μ-I) 2 HgI 2 · 3CH 2 Cl 2 (6) have been determined. Copyright

Synthesis of Fe-M complexes (M = Mo, Mn, Fe, Co, Ni, Zn, Cd, Hg) using trans-Fe(EtPhPpy)2(CO)3 as an organometallic tridentate ligand molecular structures of (CO)3Fe(μ-EtPhPpy)2Mo(CO)3 and (CO)3Fe(μ-EtPhPpy)2Cd(SCN)2 (EtPhPpy = 2-(ethylphenylphosphino)pyridine)

Abstract trans -Fe(EtPhPpy) 2 (CO) 3 reacts with Mo(CO) 6 and M(SCN) 2 (M = Mn, Fe, Co, Ni, Zn, Cd, Hg) to form binuclear complexes containing an Fe-M bond. Crystal and molecular structures of the title complexes have been determined by X-ray analysis, which yielded Fe(0)-Mo(0) and Fe(0)-Cd(II) bonded lengths of 2.922(1) A and 2.648(1) A respectively.

Palladium complexes with simultaneous O:S coordination, syntheses, structures and characterization of complexes with 2-mercaptophenol or 2-mercaptopyridine N-oxide

Abstract Complexes (Et4N)2[Pd2(mp)2(Hmp)2] (1) and [Pd(mpo)2] (2) synthesized from the reactions of palladium chloride with 2-mercaptophenol (H2mp) and 2-mercatopyridine N-oxide (Hmpo) or 2,2′-dithiobis(pyridine N-oxide) (dtpo), respectively, have been characterized by X-ray diffraction analyses and studied by IR, Raman, 1H and 13C NMR, and EI-MS techniques. The palladium atoms in the two compounds are in square planar environments. The average PdO distances are 2.009 A and 2.043 A for 1 and 2, respectively. The results of EHMO calculations show that the PdO bonds are weaker than the PdS bonds in both compounds and large delocalized π bonds extend in the (mp)2Pd2S2 plane in 1 and in the Pd(mpo)2 plane in 2. The reaction of [Ni(mpo)2] with [Pd(COD)Cl2] led to the formation of 2 also, which implies that the bidentate O:S ligand mpo readily transfers from the NiII to the PdII ion.

Crystal structure and properties of a new five-coordinate manganese superoxide dismutase mimic

Abstract A new five-coordinate manganese(II) complex Mn(NTB)(C 8 H 4 O 4 )·DMF·0.5CH 3 OH·0.5H 2 O, where NTB is tris(2-benzimidazolyl-methyl) amine and C 8 H 4 O 4 2− is the dianion of terephthalic acid, was prepared and characterized by X-ray crystallography. It crystallizes in the tetragonal system, space group l 4 1 / a with a = 28.063(1), c = 22.8680(1) A , Z = 16 and V = 18009(9) A 3 . The structure was solved by direct methods and refined by full-matrix least-squares(on F ) to residual R ( wR ) values of 0.0785 (0.076). The manganese in the complex adopts a distorted trigonal-bipyramidal coordination geometry with an N 4 O ligand donor set and bears structural similarities to the active site of Mn-superoxide dismutase. The X-band electron paramagnetic resonance spectrum of the complex exhibits a six-line manganese hyperfine pattern with g = 2.005, A = 94 G. The electrochemical properties of the complex were studied in DMF by cyclic voltammetry. The complex can catalyse the dismutation of superoxide (O 2 − ) effectively in the riboflavin-methionine-nitro blue tetrazolium assay.

A FACILE SYNTHESIS OF RHODIUM(III) PORPHYRIN-SILYLS

Abstract Rhodium(III) porphyrin–silyls [Me 3 SiRhT(p-X)PP (X=H, Me)] were synthesized from the reactions of the rhodium(I) porphyrin anions, generated from the reduction of the rhodium(III) porphyrin chlorides with the sodium amalgam in toluene, with degassed Me 3 SiCl at room temperature. A single crystal structure of (5,10,15,20-tetraphenylporphyrinato)(trimethylsilyl)rhodium(III) (1) showed that the Rh–Si bond length is equal to 2.305 A.

Bis(carboxylato) complexes of platinum(II). Structural and bonding analysis of [Pt(O2CR)2(L–L)][L–L = 2PPh3, Ph2PCH2PPh2 or Fe(C5H4PPh2)2; R = Me, CF3, Pri or Ph]

Treatment of [PtCl2(L–L)][L–L = 2 PPh3, Ph2PCH2PPh2(dppm) or Fe(C5H4PPh2)2(dppf)] with Ag(O2CR)(R = Me, CF3, Pri or Ph) at room temperature generally gave [Pt(O2CR)2(L–L)] in moderate to good yields. The crystal and molecular structures of [Pt(O2CMe)2(dppf)]·H2O, [Pt(O2CPh)2(dppf)]·CH2Cl2 and [Pt(O2CCF3)2(dppm)] have been determined by single-crystal X-ray diffractometry. All these complexes show a mononuclear square-planar structure with a chelating diphosphine and two neighbouring (cis) carboxylates in a monodentate mode. These structures contrast those of the parent [Pt4(µ-O2CMe)8] and its derivative [Pt4(en)4(µ-O2CMe)4]4+(en = ethylenediamine) which are tetrameric, based on octahedral PtII, and contain bridging acetates and direct Pt–Pt bonds. Fenske–Hall molecular orbital calculations of these structures confirmed the existence of Pt–Pt bonding interactions. The presence of hard and electronegative ligands like en and acetate incurs a deficiency in σ-electron density, compared to virtually filled non-bonding orbitals; the former is alleviated by Pt–Pt bonding. d8 Complexes with ligands like phosphines possessing both σ-donating and π-accepting qualities appear to favour the usual square-planar geometry.

Syntheses and X-ray structural characterization of phosphine cobalt(II) complexes with 2-mercaptobenzothiazole

Abstract Mononuclear cobalt(II) complexes Co(mbt-N)2(PBu3n)2 (1) (Hmbt = 2-mercaptobenzothiazole; PBu3n = tri-n-butyphosphine) and Co(mbt-S, N)2(dppe)·MeCN (2) [dppe = 1, 2-bis(diphenylphosphino) ethane] were synthesized and characterized by X-ray crystallography, IR and EPR spectra, cyclic voltammetric data and magnetic susceptibility measurements. The Co atom in (1) exhibits an approximate square-planar geometry with the heterocyclic N-donors from mbt bonding to the cobalt atom in a monodentate mode. Complex (2) has a distorted octahedral environment of Co with both the exocyclic-S and the hetero-N donors of mbt bound to the cobalt atom in a bidentate chelating mode. The Co atom in both complexes shows spin state of S =3/2 with μeff of 4.25 and 4.40μB for 1 and 2, respectively.

X-ray crystal structure of copper(II) and silver(I) complexes with the new ligand 1,4-bis(5′-methyl-2,2′-bipyridine-5-ethyl)-benzene: the effects of substituent and linking position on the assembly of helical complexes

Abstract A new tetradentate ligand 1,4-bis(5′-methyl-2,2′-bipyridine-5-ethyl)-benzene(p-bpy) and its CuII and AgI complexes were synthesized. In complex 1, Cu(p-bpy)[ClO4]2·0.5MeCN, the four nitrogen atoms of the ligand coordinate with one CuII to form a flattened tetrahedron. The metal ion also has weak interactions with two ClO4−, which link the CuII ions in a one dimensional fashion to make an infinite chain. In complex 2, Ag(p-bpy)[ClO4], the coordination geometry of AgI is flattened tetrahedron.