Gene-Hsian Lee

Metal–metal interaction in polynuclear silver(I) complexes: spectroscopy, luminescent properties and X-ray crystal structure of [Ag3(dppp)2(MeCN)2(ClO4)2]+[dppp = bis(diphenylphosphinophenylphosphine)]

The [Ag3(dppp)2(MeCN)2(ClO4)2]+ complex displays 1(dσ*→ pσ) transition at 288 nm and solid state photoluminescence at 467 nm; the Ag–Ag distances are 2.943–-3. 014 (2)A.

STRUCTURE AND MAGNETIC PROPERTIES OF A NOVEL CHLORO-BRIDGED POLYMERIC CADMIUM(II) COMPLEX WITH PYRIDYL-SUBSTITUTED NITRONYL NITROXIDE

Abstract A complex of 2(2-pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxy-3-N-oxide (NIToPy) with Cd(II)Cl2, [(CdCl2)3-(NIToPy)2(C2H5)2], has been structurally and cryomagnetically characterized. The structure is based on a layered zigzagging polymeric chain along the (101) plane; the Cd(II) ions are linked into infinite chains by double chlorine bridges alternating between one CdCl4O2 and two CdCl4NO octahedral coordination units. The temperature-dependence of the magnetic susceptibility reveals the presence of a Heisenberg antiferromagnetic exchange interaction of a two spin S = 1 2 system, with J = −0.25 cm−1 associated with the intermolecular interaction between the NO groups of two neighboring NIToPy radicals.

Manganese(II) chloride catalyzed highly efficient one-pot synthesis of propargylamines and fused triazoles via three-component coupling reaction under solvent-free condition

A one-pot green and highly efficient method for the synthesis of propargylamines and diastereoselective synthesis of fused triazoles via three-component coupling in the presence of manganese(II) chloride as a catalyst and a catalyst-free 1,3-dipolar cycloaddition reaction, respectively, without using a co-catalyst or activator is reported. This methodology is efficient, eco-friendly, operationally simple and effective for reactions involving aromatic, aliphatic, and heterocyclic aldehydes, and provides an easy access to propargylamines in excellent yields, fused triazoles in good yield and excellent diastereoselectivities.

Stereocontrolled functionalization of acyclic molybdenum-η3-allyl complexes: a new approach to the stereoselective synthesis of 1,3-diols

Functionalization of [CpMo(CO)2(η3-syn-1-C3H4COCH3)] proceeds in a highly stereospecific manner; the Mo-η3-allyl unit is effective in directing asymmetric carbon induction in the course of s-trans-η4-cis-pentadiene formation, aldol condensation and asymmetric 1,3-diol synthesis.

Tungsten-mediated syntheses, skeletal rearrangement and synthetic applications of η1-2,5-dihydro-3-furanyl rings

The syntheses, acid-catalysed rearrangements and demetallation chemistry of CpW(CO)3(η1-[graphic omitted]H2)(R = CHCH2, CCPh; R1= alkyl, phenyl; Cp = C5H5) are reported, and their synthetic-utility in organic reactions is demonstrated.

Stereo- and regio-controlled carbon–carbon bond formation mediated by tungsten in the s-trans-η4-diene cationic intermediates

The tungsten-η3-2-substituted pentadienyl complexes WC5H5(CO)2(syn-η3-R-C5H6)(R = COOMe; CMeCH2) undergo BF3-catalysed stereoselective carbon-carbon bond formation with aldehydes to afford isolable s-trans-diene cations which after hydrolysis produces tungsten-η3-allyl-1,3-diols; utilization of the diols for stereoselective synthesis of α-methylene-γ-butyrolactones, furanone skeletons, have been reported in good yields (> 80%).

Synthesis, characterization and structure of dicarbonyl-(η5-indenyl)(η3-pentadienyl)molybdenum and its phosphine derivatives

Abstract The reaction between Mo(CO) 2 (η 3 -C 5 H 7 )(CH 3 CN) 2 Cl and LiC 9 H 7 or NaC 13 H 9 gives (η 5 -C 9 H 7 )Mo(CO) 2 (η 3 -C 5 H 7 ) ( 1 ) or (η 5 -C 13 H 9 )Mo(CO) 2 (η 3 -C 5 H 7 ) ( 2 ) respectively. Photolysis of 1 with excess PMe 3 and PMe 2 Ph in ether at - 20°C yields (η 5 -C 9 H 7 )Mo(CO)(PR 3 )(η 3 -C 5 H 7 ) (PR 3 = PMe 3 ( 3 ), PMe 2 Ph ( 4 )). Complexes 3 and 4 exist as exo and endo isomers and have been fully characterized by elemental analyses, and from their IR, mass, and 1 H NMR spectra. The crystal structure of 1 has been determined by an X-ray diffraction study; crystallographic data: space group P 2 1 / C a 7.955(10), b 12.531(3), c 13.987(5) A, β 100.86(7)°, Z = 4, R 2.4%, R w 2.3%.

Formation of molybdenum-η4-trimethylenemethane cations through carbon–carbon bond formation

In the presence of BF3·Et2O, the molybdenum–η3-allyl complex [Mo(η5-C5H5)(CO)2{η3-anti-1-Me, 2-(CH2CPh)C3H3}] reacts with benzaldehyde, methyl vinyl ketone and acetone to give the corresponding η4-trimethylenemethane cations; the crystal structure of a pyran complex generated from such cations and of a related complex are reported.

Synthesis of decahydropyrrolo[1,2-a]tetrazolo[1,5-d]pyrazines via Strecker reaction and intramolecular [3+2] cycloaddition

This paper reports an efficient two-step method for synthesizing a series of new (5aS,10R)-10-aryl-5,5a,6,7,8,10-hexahydropyrrolo[1,2-a]tetrazolo[1,5-d]pyrazines by a catalyst-free three-component Strecker reaction followed by an intramolecular [3+2] cycloaddition. The first step involved three-component coupling of aldehydes, (S)-2-(azidomethyl)pyrrolidine and potassium cyanide in presence of water to form (R)-2-((S)-2-(azidomethyl)pyrrolidin-1-yl)-2-phenylacetonitriles (3a–3v). In the next step products (3a–3v) underwent intramolecular [3+2] cycloaddition on heating to form (5aS,10R)-10-aryl-5,5a,6,7,8,10-hexahydropyrrolo[1,2-a]tetrazolo[1,5-d]pyrazines (4a–4v). The present methodology is cost-effective, operationally simple, and applicable for various aromatic, aliphatic and heterocyclic aldehydes, and gives desired products in satisfactory yields and diastereoselectivities. A proposed mechanism for synthesis of 3a and 4a is reported.

π-Face differentiation in Michael reaction to the enone group adjacent to the (η-C5H5)Mo(CO)2(π-allyl) fragment: a new approach to the stereoselective synthesis of 2,3,4,5-tetrasubstituted-tetrahydrofuran compounds

The stereochemical outcome of the 1,4-addition of organocopper reagents to (η-C5H5)Mo(CO)2[η3-1-(E)-C3H4COCHCHR] compounds has been elucidated; utilization of this reaction for synthesis of 2,3,4,5-tetrasubstituted tetrahydrofuran is demonstrated.