Chalcogenated Schiff bases: Complexation with palladium(II) and Suzuki coupling reactions
作者:PRADHUMN SINGH、G K RAO、MOHD SALMAN KARIM、AJAI K SINGH
DOI:10.1007/s12039-012-0323-4
日期:2012.11
appear to be reactive (noticed for the first time) for making >C=N bond, of course one at a time only. The 1H, 13C1H}, 77Se1H} and 125Te1H} NMR spectroscopy have been used to establish the co-existence of two products, which were found in the ratio 53:47 (E = S), 55:45 (E = Se) and 81:19 (E = Te). The larger amount is of the one in which C=O group away from NH is derivatized. The two products are not
Ligand concentration and reaction time controlled successive substitution of chloro and η6-benzene of di-μ-chlorobis{η6-benzene)dichlororuthenium(II)} with selenated Schiff base: Formation of half sandwich Ru(II) complex highly active catalyst for oxidation of alcohols
作者:Pradhumn Singh、Dipanwita Das、Monika Singh、Ajai K. Singh
DOI:10.1016/j.inoche.2009.11.011
日期:2010.2
Schiff base (L) synthesized by reacting 2-methylthiobenzeldehyde with 2-(phenylseleno)ethylamine on reaction with di-mu-chlorobiseta(6)-benzene)dichloro-ruthenium(II)}(a) forms two type of species: (i) [Ru(L)(2)][PF6](2) (1) [L:a = 4:1 and reaction time similar to 8 h] and (ii) [Ru(eta(6)-C6H6)(L)][PF6](2) (2) [L:a = 2:1 and reaction time similar to 1 h]. This is first example in which chloro as well benzene ring both are successively substituted by controlling metal:ligand ratio and duration of reaction. The geometry around Ru in complex 1 is distorted octahedral. The 2 has a pseudo-octahedral half sandwich "piano-stool" disposition of ligands around Ru. The Ru-Se distances are 2.4683(10)-2.5082(7) angstrom. The proton and carbon-13 NMR spectra of L and its both complexes I and 2 authenticate them. The 2 shows high catalytic activity for oxidation of primary and secondary alcohols both (TON upto 9.6 x 10(4); TOF upto 4.80 x 10(4) h(-1)). (C) 2009 Elsevier B.V. All rights reserved.
Palladium(II) complexes of tridentate chalcogenated Schiff bases and related ligands of (S, N, S/Se/Te) type: Synthesis and structural chemistry
作者:Pradhumn Singh、Ajai K. Singh
DOI:10.1016/j.ica.2012.01.007
日期:2012.5
The reactions in CH3CN between PdCl2 and Schiff base ligands, 2-MeSC6H4-CH=NCH2CH2E-C6H4-4-R (L1-L3) (E = S or Se, R = H; E = Te, R = OCH3) and their reduced derivatives 2-MeSC6H4CH2-NHCH2CH2E-C6H4-4-R (L4-L6) followed by treatment with AgPF6 or AgClO4 have resulted in complexes [PdCl(L)][ X] (1-6; L = L1-L6; X = PF6 or ClO4) which have been characterized by IR, H-1, C-13H-1}, Se-77H-1} and Te-125H-1} NMR spectroscopy. Single crystal structures of complexes 1-6 reveal nearly square planar geometry around palladium in all of them (Pd-Se = 2.4045(16)-2.4065(6) angstrom; Pd-Te = 2.5052(9)-2.5307(13) angstrom). The various non-covalent interactions in the crystals result in the formation of chains, rings and caging of anions between cations. (C) 2012 Elsevier B.V. All rights reserved.
Transfer Hydrogenation of Ketones and Catalytic Oxidation of Alcohols with Half-Sandwich Complexes of Ruthenium(II) Designed Using Benzene and Tridentate (S, N, E) Type Ligands (E = S, Se, Te)
作者:Pradhumn Singh、Ajai K. Singh
DOI:10.1021/om100807b
日期:2010.12.13
and 2.6234(6)−2.6333(7) Å, respectively. Complexes 1−6 have been found to be efficient catalysts for catalytic oxidation of alcohols with N-methylmorpholine-N-oxide, tBuOOH, NaOCl, and NaIO4 and transferhydrogenation reaction of ketones with 2-propanol. The TON values are up to 9.9 × 104 and 9.8 × 104 for two catalytic processes, respectively. The oxidation probably involves the formation of intermediate
组合物的复合物FAC - [(η 6 -C 6 H ^ 6)的Ru(大号)] [PF 6 ] [X](1 - 6 ; X = PF 6或Cl),通过反应形成2- MESC 6 ħ 4 = NCH 2 CH 2 E-C 6 H ^ 4 -4-R(L1 - L3)和2- MESC 6 ħ 4 CH 2 -NHCH 2 CH 2 E-C 6 H ^ 4 -4-R(L4 - L6)(其中,E = S或Se,R = H; E =碲,R = OME)与[(η 6 -C 6 H ^ 6)的RuCl(μ-Cl)的} 2 ]和NH 4 PF 6,已经其特征在于1 H,13 C 1 H},77 Se 1 H}和125 Te 1 H} NMR光谱法和X射线晶体学。Ru-Se和Ru-Te键长分别在2.4837(14)-2.4848(14)和2.6234(6)-2.6333(7)Å范围内。配合物1 -