Unprecedented Reaction Pathway of Sterically Crowded Calcium Complexes: Sequential C−N Bond Cleavage Reactions Induced by C−H Bond Activations

Five bis(quinolylmethyl)‐(1H ‐indolylmethyl)amine (BQIA) compounds, that is, {(quinol‐8‐yl‐CH₂)₂NCH₂(3‐Br‐1H ‐indol‐2‐yl)} ( L¹H ) and {[(8‐R³‐quinol‐2‐yl)CH₂]₂NCH(R²)[3‐R¹‐1H ‐indol‐2‐yl]} ( L^2–5H ) ( L²H : R¹=Br, R²=H, R³=H; L³H : R¹=Br, R²=H, R³=i Pr; L⁴H : R¹=H, R²=CH₃, R³=i Pr; L⁵H : R¹=H, R²=n Bu, R³=i Pr) were synthesized and used to prepare calcium complexes. The reactions of L^1–5H with silylamido calcium precursors (Ca[N(SiMe₂R)₂]₂(THF)₂, R=Me or H) at room temperature gave heteroleptic products ( L^{1, 2} )CaN(SiMe₃)₂ ( 1 , 2 ), ( L^{3, 4} )CaN(SiHMe₂)₂ ( 3 a , 4 a ) and homoleptic complexes ( L^{3, 5} )₂Ca ( D3 , D5 ). NMR and X‐ray analyses proved that these calcium complexes were stabilized through Ca⋅⋅⋅C−Si, Ca⋅⋅⋅H−Si or Ca⋅⋅⋅H−C agostic interactions. Unexpectedly, calcium complexes (( L^3–5 )CaN(SiMe₃)₂) bearing more sterically encumbered ligands of the same type were extremely unstable and underwent C−N bond cleavage processes as a consequence of intramolecular C−H bond activation, leading to the exclusive formation of (E )‐1,2‐bis(8‐isopropylquinol‐2‐yl)ethane.     

Chemical,electrochemical and structural studies of some cis -dioxomolybdenum(VI) complexes of two tridentate ONS chelating ligands

Several cis-dioxomolybdenum complexes of two tridentate ONS chelating ligands H₂L¹ and H₂L² (obtained by condensation of S-benzyl and S-methyl dithiocarbazates with 2-hydroxyacetophenone) have been prepared and characterized. Complexes 1 and 2 are found to be of the form MoO₂ (CH₃OH) L¹?·?CH₃OH and MoO₂L, respectively, (where L^2–?=?dianion of H₂L¹ and H₂L²). The sixth coordination site of the complexes acts as a binding site for various neutral monodentate Lewis bases, B, forming complexes 3–10 of the type MoO₂LB (where B?=?γ-picoline, imidazole, thiophene, THF). The complexes were characterized by elemental analyses, various spectroscopic techniques, (UV-Vis, IR and ¹H NMR), measurement of magnetic susceptibility at room temperature, molar conductivity in solution and by cyclic voltammetry. Two of the complexes MoO₂(CH₃OH) L¹?·?CH₃OH (1) and MoO₂L¹(imz) (5) were structurally characterized by single crystal X-ray diffraction. Oxo abstruction reactions of 1 and 5 led to formation of oxomolybdenum(IV) complex of the MoOL type.     

Synthesis, Spectroscopic and Electrochemical Investigations of Two vic-Dioximes and Their Mononuclear Ni（Ⅱ）, Cu（Ⅱ） and Co（Ⅱ） Metal Complexes Containing Morpholine Group

Two vic-dioxime ligands （LxH2） containing morpholine group have been synthesized from 4-[2-（dimethylaminoethyl）] morpholine with anti-phenylchloroglyoxime or anti-monochloroglyoxime in absolute THF at -15 ℃. Reaction of two vic-dioxime ligands with MCl2·nH2O （M： Ni, Cu or Co and n=2 or 6） salts in 1 ： 2 molar ratio afforded metal complexes of type [M（LxH）2] or [M（LxH）2·2H2O]. All of metal complexes are non-electrolytes as shown by their molar conductivities （Am） in DMF （dimethyl formamide） at 10^-3 mol·L^-1. Structures of the ligands and metal complexes have been solved by elemental analyses, FT-IR, UV-Vis, ^1H NMR and ^13C NMR, magnetic susceptibility measurements, molar conductivity measurements. Furthermore, redox properties of the metal complexes were investigated by cyclic voltammetry.     

Synthesis,characterization, and in vitro antimicrobial activities of organotin(IV) complexes of Schiff bases with ONO‐type donor atoms

A new series of diorganotin complexes of the type R₂SnL (L¹: N‐(2‐hydroxy‐5‐chlorophenyl)‐ 3‐ethoxysalicylideneimine, R = Me, (Me₂SnL¹), R = n‐Bu, (n‐Bu₂SnL¹), R = Ph, (Ph₂SnL¹), L²: N‐(2‐hydroxy‐4‐nitro‐5‐chlorophenyl)‐3‐ethoxysalicylideneimine, R = Ph, Ph₂SnL², L³: N‐(2‐hydroxy‐4‐nitrophenyl)‐3‐methoxysalicylideneimine, R = Me, (Me₂SnL³), R = n‐Bu, (n‐Bu₂SnL³), L⁴: N‐(2‐hydroxy‐4‐nitrophenyl)‐3‐ethoxysalicylideneimine, R = Me, (Me₂SnL⁴), R = n‐Bu, (n‐Bu₂SnL⁴)) were synthesized and characterized by elemental analysis, infrared (IR), ¹H, and ¹³C NMR mass spectroscopic techniques, and electrochemical measurements. Ph₂SnL¹ and Ph₂SnL² were also characterized by X‐ray diffraction analysis and were found to show a fivefold C₂NO₂ coordination geometry nearly halfway between a trigonal bipyramidal and distorted square pyramidal arrangement. The C Sn C angles in the complexes were calculated using Lockhart's equations with the ¹J(^117/119Sn‐¹³C) and ²J(^117/119Sn‐¹H) values from the ¹H NMR and ¹³C NMR spectra. Biocidal activity tests against several micro‐organisms and some fungi indicate that all the complexes are mildly active against Gram (+) bacteria and the fungi, A. niger and inactive against Gram (−) bacteria. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:373–385, 2010; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20628     

Zinc(II) complexes of Triaza and Amidinate ligands: Efficient initiators for the ring‐opening polymerization of ε‐Caprolactone and rac‐Lactide

Zinc complexes supported by tertiary 1,3,5‐triazapenta‐1,3‐dienate ligand (L¹) and N ‐benzoyl‐N′ ‐arylbenzamidinate [aryl =2,6‐diisopropylphenyl (L²), phenyl (L³)] ligands have been synthesized and characterized. The reaction of L¹H with ZnEt₂ affords a mononuclear zinc complex [L¹ZnEt] ( 1 ) in good yield. Tetra nuclear zinc complex [(L¹)₂Zn₄O(OAc)₄] ( 2 ) is prepared by treating L¹H with one equivalent of Zn(OAc)₂ in toluene. Further, dinuclear zinc complexes [L²ZnEt]₂ ( 3 ) and [L³ZnEt]₂ ( 4 ) are obtained in good yields from L²H and L³H with ZnEt₂ in toluene respectively_. The complexes 1–4 have been characterized by ¹H/¹³C NMR spectroscopy and single crystal X‐ray diffraction studies. All of the complexes have been explored for their catalytic activity toward the ring‐opening polymerization (ROP) of ε ‐caprolactone. It has been found that complex 1 is an active catalyst for the polymerization of ε ‐caprolactone in presence of a cocatalyst benzyl alcohol (BnOH). While complex 2 is as active as 1 there is no need for a cocatalyst for the polymerization to proceed. Dinuclear zinc complexes 3 and 4 show very high activity for the ROP of ε ‐caprolactone (CL) and rac ‐lactide (LA) without requiring a cocatalyst. The resultant polymers are found to have very high molecular weight (M _n = 296 X 10³ g mol⁻¹) and relatively narrow polydispersity index compared to 1 and 2 .     

Oxomolybdenum(VI) and (IV) complexes of pyrazole derived ONO donor ligands – synthesis,crystal structure studies and spectroelectrochemical correlation

Four cis-dioxomolybdenum complexes of general formula [MoO₂(Lⁿ)EtOH] (n = 1–4) and one oxomolybdenum(IV) complex [MoO(L⁴)EtOH], with potentially tridentate Schiff bases derived from 5-methyl pyrazole-3-carbohydrazide and salicylaldehyde/substituted salicylaldehyde/o-hydroxy acetophenone have been prepared. The Mo(IV) complex is derived from the Mo(VI) dioxo complex by oxotransfer reaction with PPh₃. The complexes are characterized by elemental analysis, electronic spectra, IR, ¹H NMR, and by cyclic voltammetry. All the Mo(VI) species are crystallographically characterized. The complexes have a distorted octahedral structure in which the ligand behaves as a binegative donor one, leaving the pyrazole –N uncoordinated towards the metal center. It is also revealed from the crystal structure that the Mo(VI) center enjoys an NO₅ donor environment.     

Robust and Electron‐Rich cis‐Palladium(II) Complexes with Phosphine and Carbene Ligands as Catalytic Precursors in Suzuki Coupling Reactions

A new imidazolinium ligand precursor [L²H]Cl ( 2 ) was prepared in 86 % yield. Compared with its imidazolium counterpart, [L¹H]Cl ( 1 ), 2 is very sensitive to moisture and can undergo ring‐opening reactions very readily. Palladium complexes with the ring‐opened products from imidazolinium salts were isolated and characterized by X‐ray crystallography. Theoretical studies confirmed that the imidazolinium salt has a higher propensity for the ring‐opening reaction than the imidazolium counterpart. New mixed phosphine/carbene palladium complexes, cis‐[PdCl₂(L)(PR₃)] (L=L¹ and L²; R=Ph, Cy), were successfully prepared. These complexes are highly robust as revealed by variable‐temperature NMR spectroscopic studies and thermal gravimetric analysis. The structural and electronic properties of the new complexes on varying the carbene group (imidazol‐2‐ylidene group (unsaturated carbene) vs. imidazolin‐2‐ylidene (saturated carbene)) and the phosphine group (PPh₃ vs. PCy₃) were studied in detail by X‐ray crystallography, X‐ray photoelectron spectroscopy, and theoretical calculations. The catalytic study reveals that cis‐[PdCl₂(L²)(PCy₃)] is a competent Pd^II precatalyst for Suzuki coupling reactions, in which unreactive aryl chlorides can be applied as substrates.     

Synthesis and Structure of Novel Dimethylcobalt(III) Complexes Containing Trimethylphosphine and Salicylaldiminato(N:O) Ligands

Dimethyl(salicylaldiminato[N:O])cobalt complexes [CoMe₂(2‐O‐C₆H₁R¹R² R³‐CH=NR⁴)L₂] (L=PMe₃) ( 1 ‐ 6 ) have been prepared through the reaction of [CoMe₃(PMe₃)₃] with the corresponding substituted salicylaldimine. The complexes were characterized with IR, ¹H NMR, ¹³C NMR, ³¹P NMR and elemental analyses. The X‐ray crystal structure of complex 1 shows an octahedral coordination of cobalt, with two equatorial cis‐methyl groups opposite to the planar N:O‐chelate ring.     

Isoprene polymerization with indolide‐imine supported rare‐earth metal alkyl and amidinate complexes

Reaction of 7‐{(N‐2,6‐R)iminomethyl)}indole ( HL¹ , R = dimethylphenyl; HL² , R = diisopropylphenyl) and rare‐earth metal tris(alkyl)s, Ln(CH₂SiMe₃)₃(THF)₂, generated new rare‐earth metal bis(alkyl) complexes LLn(CH₂SiMe₃)₂(THF) [L = L¹: Ln = Lu ( 1a ), Sc ( 1b ); L = L²: Ln = Lu ( 3a ), Sc ( 3b )] and mono(alkyl) complexes L²₂Lu(CH₂SiMe₃) ( 4a ). Treatment of alkyl complexes 1a and 4a with N,N′‐diisopropylcarbodiimide afforded the corresponding amidinates L¹Lu{iPr₂NC(CH₂SiMe₃)NiPr₂}₂ ( 2a ) and L²₂Lu{iPr₂NC(CH₂SiMe₃)NiPr₂} ( 5a ), respectively. These new rare‐earth metal alkyls and amidinates except 4a in combination with aluminum alkyls and borate generated efficient homogeneous catalysts for the polymerization of isoprene, providing high cis‐1,4 selectivity and high molar mass polyisoprene with narrow molar mass distribution (M_n = 2.65 × 10⁵, M_w/M_n = 1.07, cis‐1,4 98.2%, −60 °C). The environmental hindrance around central metals arising from the bulkiness of the ligands, the Lewis‐acidity of rare‐earth metal ions, the types of aluminum tris(alkyl)s and borate, and polymerization temperature influenced significantly on both the catalytic activity and the regioselectivity. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5251–5262, 2008     

Organophosphine/phosphite‐stabilized silver(I) complexes bearing N‐hydroxysuccinimide ligand: synthesis,solid state structure and their potential use as MOCVD precursors

Six organophosphine/phosphite‐stabilized silver(I) N‐hydroxysuccinimide complexes of type [C₄H₄NO₃Ag?L_n] (L = PPh₃; n = 1, 2a; n = 2, 2b; L = P(OEt)₃; n = 1, 2c; n = 2, 2 d; L = P(OMe)₃; n = 1, 2e; n = 2, 2f) were prepared. These complexes were obtained in high yields and characterized by elemental analysis, ¹H NMR, ¹³ C{¹H} NMR and IR spectroscopy, respectively. The molecular structure of 2b has been determined by X‐ray single‐crystal analysis in which the silver atom is in a distorted tetrahedral geometry. An interstitial methanol solvent molecule is hydrogen bonded to the oxygen atom of N‐hydroxysuccinimide molecule. Complex 2f was used to deposit silver films by metal‐organic chemical vapor deposition (MOCVD) for the first time. The silver film obtained at 480 °C is dense and homogeneous, which is composed of many well‐isolated, granular particulates spreading all over the substrate surface. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis and Characterization of a Series of New Asymmetric Salphen Mono- and Binuclear Metal Complexes

Two novel asymmetric salen ligands H₂L¹ [N‐phenyl‐N‐(2‐hydroxy‐5‐methylphenyl)‐N′‐(2‐hydroxy‐3‐meth‐ oxylphenyl)‐o‐phenyldiamine] and H₂L² [N‐phenyl‐N‐(2‐hydroxy‐5‐chlorophenyl)‐N′‐(2‐hydroxy‐3‐methoxyl‐ phenyl)‐o‐phenyldiamine] and their metal complexes MLⁿ (M=Zn, Co, Ni, Cu; n=1, 2) have been prepared and characterized by elemental analyses, ¹H NMR, ESI‐MS, FT‐IR and UV‐Vis spectra. In particular, the complex ZnL¹, the binuclear monosalphen complex, was synthesized and studied in detail using ¹H NMR and ESI‐MS techniques. For other metal complexes under the same reaction conditions, only mononuclear complexes were obtained. The results are relevant to both the metal ions and the structure of ligands.     

Self‐Assembly of Discrete Copper(I)‐Halide Complexes with Diacylthioureas

Three diacylthioureas 1,4‐C₆H₄[C(O)NHC(S)NHAr]₂ (Ar = 2,6‐iPr₂C₆H₃) ( L¹ , 1 ), 1,3‐C₆H₄[C(O)NHC(S)NHAr]₂ ( L² , 2 ), and 1,3‐C₆H₄[C(O)NHC(S)NHAr′]₂ (Ar′ = 2,6‐Me₂C₆H₃) ( L³ , 3 ) were synthesized and characterized. The Cu^I complexes from the reactions of bipodal ligands Lⁿ with CuX (X = Cl, Br, I) were structurally investigated by single‐crystal X‐ray diffraction methods. Treatment of L¹ with CuX gave the metallamacrocyclic complexes ( L¹ CuX)₂ [X = Cl ( 4 ), Br ( 5 ), I ( 6 )] with the ligand to metal in a ratio of 2:2, where both sulfur and halide anions function as terminal substituents. In contrast, when L² or L³ was reacted with CuBr, the two Lⁿ ligands coordinate to four copper atoms each in a bridging and terminal fashion to yield [ Lⁿ (CuBr)₂]₂ [n = 2 ( 7 ), 3 ( 8 )]. The obtained S₄Cu₄Br₄ core contains all four bromide anions in bridging positions. The reaction of L³ with CuX (X = Cl, I) gave the 3:3 trinuclear complexes ( L³ CuX)₃ [X = Cl ( 9 ) I ( 10 )], interconnected by halide bridges. The obtained diacylthioureas ( 1 – 3 ) and their Cu^I complexes ( 4 – 10 ) were also characterized by elemental analysis, FT‐IR, ¹H and ¹³C NMR spectroscopy.     

Dioxomolybdenum(VI) complexes of hydrazone phenolate ligands - syntheses and activities in catalytic oxidation reactions

The new cis-dioxomolybdenum (VI) complexes [MoO₂(L²)(H₂O)] (2) and [MoO₂(L³)(H₂O)] (3) containing the tridentate hydrazone-based ligands (H₂L² = N'-(3,5-di-tert-butyl-2-hydroxybenzylidene)-4-methylbenzohydrazide and H₂L³ = N'-(2-hydroxybenzylidene)-2-(hydroxyimino)propanehydrazide) have been synthesized and characterized via IR, ¹H and ¹³C NMR spectroscopy, mass spectrometry, and single crystal X-ray diffraction analysis. The catalytic activities of complexes 2 and 3, and the analogous known complex [MoO₂(L¹)(H₂O)] (1) (H₂L¹ = N'-(2-hydroxybenzylidene)-4-methylbenzohydrazide) have been evaluated for various oxidation reactions, viz. oxygen atom transfer from dimethyl sulfoxide to triphenylphosphine, sulfoxidation of methyl-p-tolylsulfide or epoxidation of different alkenes using tert-butyl hydroperoxide as terminal oxidant. The catalytic activities were found to be comparable for all three complexes, but complexes 1 and 3 showed better catalytic performances than complex 2, which contains a more sterically demanding ligand than the other two complexes.     

Synthesis and Structural Characterization of β‐Ketoiminate‐Stabilized Gallium Hydrides for Chemical Vapor Deposition Applications

Bis‐β‐ketoimine ligands of the form [(CH₂)_n{N(H)C(Me)?CHC(Me)?O}₂] (LⁿH₂, n=2, 3 and 4) were employed in the formation of a range of gallium complexes [Ga(Lⁿ)X] (X=Cl, Me, H), which were characterised by NMR spectroscopy, mass spectrometry and single‐crystal X‐ray diffraction analysis. The β‐ketoimine ligands have also been used for the stabilisation of rare gallium hydride species [Ga(Lⁿ)H] (n=2 ( 7 ); n=3 ( 8 )), which have been structurally characterised for the first time, confirming the formation of five‐coordinate, monomeric species. The stability of these hydrides has been probed through thermal analysis, revealing stability at temperatures in excess of 200 °C. The efficacy of all the gallium β‐ketoiminate complexes as molecular precursors for the deposition of gallium oxide thin films by chemical vapour deposition (CVD) has been investigated through thermogravimetric analysis and deposition studies, with the best results being found for a bimetallic gallium methyl complex [L³{GaMe₂}₂] ( 5 ) and the hydride [Ga(L³)H] ( 8 ). The resulting films ( F5 and F8 , respectively) were amorphous as‐deposited and thus were characterised primarily by XPS, EDXA and SEM techniques, which showed the formation of stoichiometric ( F5 ) and oxygen‐deficient ( F8 ) Ga₂O₃ thin films.     

Synthesis and Characterization of Di‐ and Tricarbonylhydridomanganese(I) Complexes

Hydrido complexes [MnH(CO)₃L^1–3] [L¹ = 1,2‐bis‐(diphenylphosphanoxy)‐ethane ( 1 ); L² = 1,2‐bis‐(diisopropylphosphanoxy)ethane ( 2 ); L³ = 1,3‐bis‐(diphenylphosphanoxy)‐propane ( 3 )] were prepared by treating [MnH(CO)₅] with the appropriate bidentate ligand by heating to reflux. Photoirradiation of a toluene solution of complexes 1 and 2 in the presence of PPh_n(OR)_3–n (n = 0, 1; R = Me, Et) leads to the replacement of a CO ligand by the corresponding monodentate phosphite or phosphonite ligand to give new hydrido compounds of formula [MnH(CO)₂(L^1–2)(L)] [L = P(OMe)₃ ( 1a – 2a ); P(OEt)₃ ( 1b – 2b ); PPh(OMe)₂ ( 1c – 2c ); PPh(OEt)₂ ( 1d – 2d )]. All complexes were characterized by IR, ¹H, ¹³C and ³¹P NMR spectroscopy. In case of compounds 2 and 3 , suitable crystals for X‐ray diffraction studies were isolated.     

Synthesis,Characterization, and Crystal Structure of Mononuclear and Dinuclear Dioxomolybdenum(VI) Complexes with Tridentate Schiff‐base Ligands. Part 2

Mononuclear [MoO₂LD], and dinuclear [MoO₂L]₂ or [MoO₂L]₂ · D dixomolybdenum(VI) complexes have been prepared by the reaction of tridentate Schiff‐base ligands L with [MoO₂(acac)₂]. The Schiff‐base ligands have been synthesized from salicylaldehyde ( 1 , 1a , 1c , 1d ), 2‐hydroxy‐1‐naphthaldehyde ( 2 , 2c ) and 2‐hydroxy‐3‐methoxybenzaldehyde ( 3a , 3b , 3c , 3d , 3e ) with 2‐amino‐p‐cresol. All prepared complexes consist of cis‐MoO₂²⁺core coordinated by Schiff‐base ligand through two deprotonated hydroxyl groups and one imino nitrogen atom. The usual octahedral coordination around the molybdenum atoms is completed by the neutral ligand D (methanol, ethanol, dimethyl sulfoxide, imidazole or 4, 4′‐bipyridine). All compounds were characterized by elemental analyses, IR spectroscopy and some of them by X‐ray crystallography ( 1a , 2c , 3a , 3b , 3c and 3e ).     

Organophosphine/phosphite‐stabilized silver(I) complexes bearing N‐acetylbenzamide ligand: synthesis,characterization and potential application in metal organic chemical vapor deposition

New N‐silver(I) acetylbenzamide complexes of type L_n?AgNC₉H₈O₂ (L = PPh₃; n = 1, 2a; n = 2, 2b; n = 3, 2c; L = P(OEt)₃; n = 1, 2d; n = 2, 2e; n = 3, 2f) were prepared. These complexes were obtained in high yields and characterized by elemental analysis, ¹H NMR, ¹³C{H} NMR, ³¹P{H} NMR and IR spectroscopy, respectively. The molecular structure of 2b has been determined by X‐ray single‐crystal analysis in which the silver atom is in a distorted tetrahedral geometry and crystallizes as cis–trans. New N‐silver(I) acetylbenzamide complexes have a four‐membered ring, which could influence their chemical and physical properties and modulate volatility. Metal organic chemical vapor deposition experiments were carried out successfully at 400°C and 450°C using 2e as precursor for the deposition of silver films, respectively. The high‐purity silver film obtained at 400°C is dense and homogeneous. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis,spectroscopic, thermal and biological aspects of drug‐based copper(II) complexes

A series of novel complexes of the type Cu(II)(L_n)₂(H₂O)₂]^•xH₂O [where L_n = L _1–4 , these ligands being described as: L ₁ , 2‐({4‐[6,7‐dihydrothieno[3,2‐c]pyridin‐5(4H)‐ylsulfonyl]phenylimino}methyl)phenol, x = 1; L ₂ , 2‐({4‐[6,7‐dihydrothieno[3,2‐c] pyridin‐5(4H)‐ylsulfonyl]phenylimino}methyl)‐5‐(methoxy)phenol, x = 2; L ₃ , 5‐chloro‐2‐({4‐[6,7‐dihydrothieno[3,2‐c]pyridin‐5(4H)‐ylsulfonyl]phenylimino}methyl)phenol, x = 2; and L ₄ , 5‐bromo‐4‐chloro‐2‐({4‐[6,7‐dihydrothieno[3,2‐c]pyridin‐5(4H)‐ylsulfonyl]phenylimino} methyl)phenol, x = 1] was investigated. They were characterized by elemental analysis, IR, ¹H‐NMR, ¹³C‐NMR and electronic spectra, magnetic measurements and thermal studies. The FAB‐mass spectrum of [Cu(II)( L ₁ )₂(H₂O)₂]^•H₂O was determined. A magnetic moment and reflectance spectral study revealed that an octahedral geometry could be assigned to all the prepared complexes. Ligands (L_n) and their metal complexes were screened for their in vitro antibacterial activity against Bacillus subtillis, Pseudomonas aeruginosa, Escherichia coli and Serratia marcescens bacterial strains. Kinetic parameters such as order of reaction (n), the energy of activation (E_a), the pre‐exponential factor (A), the activation entropy (ΔS^≠), the activation enthalpy (ΔH^≠) and the free energy of activation (ΔG^≠) are reported. Copyright © 2011 John Wiley & Sons, Ltd.     

Triphenylphosphinopalladium(II) complexes with ONO‐donor ligands: syntheses,structures and catalytic applications in C?C cross‐coupling reactions

Reactions of 1‐((2‐hydroxy‐5‐R‐phenylimino)methyl)naphthalen‐2‐ols (H₂Lⁿ , n  = 1–3 for R = H, Me, Cl, respectively) with [Pd(PPh₃)₂Cl₂] and Et₃N in toluene under reflux produced three new mononuclear square‐planar palladium(II) complexes with the general formula [Pd(Lⁿ )(PPh₃)] ( 1 , R = H; 2 , R = Me; 3 , R = Cl). All the complexes were characterized using elemental analysis, solution conductivity and various spectroscopic (infrared, UV–visible and NMR) measurements. Molecular structures of 1 , 2 , 3 were confirmed using single‐crystal X‐ray diffraction analysis. In each complex, the fused 5,6‐membered chelate rings forming phenolate‐O, azomethine‐N and naphtholate‐O donor (Lⁿ )²⁻ and the PPh₃ form a square‐planar ONOP coordination environment around the metal centre. Infrared and NMR spectroscopic features of 1 , 2 , 3 are consistent with their molecular structures. Electronic spectra of the three complexes display several strong primarily ligand‐centred absorption bands in the range 322–476 nm. All the complexes were found to be effective catalysts for carbon–carbon cross‐coupling reactions of arylboronic acids with aromatic and heteroaromatic aldehydes to form the corresponding diaryl ketones. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis and Structure of a Series of New Molybdenum(VI) Complexes with the Esters of 2‐Mercaptonicotinic Acid

The novel dioxomolybdenum(VI) complexes with methyl ( 1 ), ethyl ( 2 ), n‐propyl ( 3 ), i‐propyl ( 4 ), n‐butyl ( 5 ) and cyclohexyl ( 6 ) ester of 2‐mercaptonicotinic acid have been prepared in the reactions of MoO₂Cl₂ and MoO₂(acac)₂ (acac = 2,4‐pentandionate) with mercaptonicotinic acid in corresponding alcohol. The esterification reaction was catalyzed by Mo^V originated from the reduction of Mo^VI with mercaptonicotinic ‐SH group with simultaneous formation of S–S bond resulting from the condensation of two 2‐mercaptonicotinic molecules. The presence of Mo^V was proved by ESR spectra. The molecular and crystal structures of 1 , 2 , 3 and 4 as well as of the by‐products 1,1′‐dithio‐2,2′‐n‐butylnicotinoate ( 7 ) and tetramethylammonium hexachloromolybdate(V) ( 8 ) have been determined by a X‐ray single crystal diffraction. The complexes 1 – 4 contain MoO₂²⁺ core with octahedral coordination of each molybdenum atom complexed by two 2‐mercaptonicotinato N and S donor atoms.