Mono‐ and heterodi‐nuclear complexes of aluminium: synthesis,characterization and antifungal activity

Some new types of mononuclear derivatives, AlL(1–4)L(1–4)H ( 1a–1d ) of aluminium were synthesized by the reaction of Al(OPrⁱ)₃ and LH₂ [XC(NYOH)CHC(R)OH], X = CH₃, Y = (CH₂)₂, R = CH₃(L1H₂); X = C₆H₅, Y = (CH₂)₂, R = CH₃(L2H₂); X = CH₃, Y = (CH₂)₃, R = CH₃(L3H₂); X = C₆H₅, Y = (CH₂)₃, R = CH₃(L4H₂) in 1:2 molar ratio in refluxing benzene. Reactions of AlL(1–4)L(1–4)H with hexamethyldisilazane in 2:1 molar ratio yielded some new ligand bridged heterodinuclear derivatives AlL(1–4)L(1–4)SiMe₃ ( 2a – 2d ). All these newly synthesized derivatives were characterized by elemental analysis and molecular weight measurements. Tentative structures were proposed on the basis of IR and NMR spectra (¹H, ¹³C, 27 Al and ²⁹Si) and FAB‐mass studies. Schiff base ligands and their mono‐ and heterodi‐nuclear derivatives with aluminium have been screened for fungicidal activities. These compounds showed significant antifungal activity against Aspergillus niger and A. flavus. Copyright © 2007 John Wiley & Sons, Ltd.     

The Synthesis and Spectroscopic Characterization of Heterobimetallic Bu2Sn(IV) Complexes Derived from Some Chelating Ligands

The interaction of Bu₂Sn(OPrⁱ)₂ with a trifunctional tetradentate Schiff base (LH₃) (where H₃L = HOC₆H₄CH═NCH₃C(CH₂OH)₂) yields the precursor complex Bu₂Sn(LH) 1, which, on equimolar reactions with different metal alkoxides [Al(OPrⁱ)₃, Bu₃Sn(OPrⁱ), Ge(OEt)₄]; Al(Medea)(OPrⁱ) (where Medea = CH₃N- (CH₂CH₂O)₂); and Me₃SiCl in the presence of Et₃N], affords, respectively, the complexes Bu₂Sn(L)Al(OPrⁱ)₂ 2, Bu₂Sn(L)Al(Medea) 3, Bu₂Sn(L)Bu₃Sn 4, Bu₂Sn(L)Ge(OEt)₃ 5, and Bu₂Sn(L)SiMe₃ 6. The reactions of 2 with 2,5-dimethyl-2,5-hexanediol in a 1:1 ratio and with acetylacetone (acacH) in a 1:2 molar ratio afforded derivatives Bu₂Sn(L)Al(OC(CH₃)₂CH₂CH₂C(CH₃)₂ O) 7 and Bu₂Sn(L)Al(acac)₂ 8, respectively. All of the derivatives 1– 8 have been characterized by elemental analyses, molecular weight measurements, and spectroscopic [IR and NMR (¹H, ¹¹⁹Sn, ²⁹Si, and ²⁷Al)] studies.     

The First Butyltin(IV) Homo- and Heterobimetallic Diethanolaminates

Equimolar reactions of BuSn(OPrⁱ)₃ with diethanolamines, RN(CH₂CH₂ OH) ₂ (abbreviated as RdeaH₂, where R = H or Me), afford dimeric isopropoxo-bridged six-coordinate butyltin(IV) complexes [{Bu(η³-Rdea)Sn(μ-OPrⁱ)}₂] (R = H ( 1 ), Me ( 2 )). Interactions between BuSn(OPrⁱ)₃ and diethanolamines (RdeaH₂) in a 1:2 molar ratio yield monomeric derivatives of the type [BuSn(Rdea)(RdeaH)] (R = H ( 3 ), R = Me ( 4 )). These homometallic complexes on 1:1 reactions with an appropriate metal alkoxide form monomeric heterobimetallic complexes of the type [BuSn (Rdea)₂ {M(OR′)_n}] (R = H, M = Al, R′ = Prⁱ, n = 2 ( 5 ); R = H, M = Ti, R = Prⁱ, n = 3 ( 6 ); R = H, M = Zr, R′ = Prⁱ, n = 3 ( 7 ); R = Me, M = Al, R′ = Prⁱ, n = 2 ( 8 ); R = Me, M = Ti, R′ = Prⁱ, n = 3 ( 9 ); R = Me, M = Ge, R′ = Et, n = 3 ( 10 )). The driving force behind this work was (i) to explore the utility of homometal complexes ( 1 ) –( 4 ) in assembling a metal alkoxide fragment via a condensation reaction and (ii) to gain insights into the structures of new compounds by NMR spectral data. All of these derivatives have been characterized by elemental analysis, spectroscopic (IR, NMR; ¹H, ²⁷Al, and ¹¹⁹Sn) studies, and molecular weight measurements. ¹¹⁹Sn NMR spectral studies indicate that both the homometallic ( 3 ) and ( 4 ) and heterobimetallic ( 5 ) – ( 9 ) complexes exist in a solution in an equilibrium of six- and five-coordinated tin(IV) species.     

Synthesis and characterization of a new class of heteronuclear derivatives of zirconium(IV)

Reactions of Zr{Al(OPrⁱ)₄}₂Cl₂ or Zr{Nb(OPrⁱ)₆}₂Cl₂ with KNb(OPrⁱ)₆/KAl(OPrⁱ)₄ and diethanolamines RN(CH₂CH₂OH)₂ [R=H(L^HH₂), Me(L^MeH₂), and Ph(L^PhH₂)] in the presence of two equivalents of Et₃N yield interesting hetero(bi- and tri-) nuclear derivatives (1)–(8) All of these new derivatives have been characterized by elemental analyses, molecular weight measurements, and spectroscopic studies.Ram C. Mehrotra - Deceased     

Synthesis and characterization of some novel triphenylarsenic(V) derivatives of monofunctional bidentate 2,2‐disubstituted benzothiazoline ligands

A series of triphenylarsenic(V) derivatives Ph₃As(OPrⁱ)[SC₆H₄N:C(R)CH₂C(O)R′] have been synthesized by the reactions of triphenylarsenic(V)‐ isoproproxide, Ph₃As(OPrⁱ)₂ with the corresponding 2,2‐disubstituted benzothiazolines of the type (where R = CH₃, R′ = CH₃( 1 ); R = CH₃, R′ = C₆H₅( 2 ); R = CH₃, R′ = 4‐CH₃C₆H₄( 3 ); R = CH₃, R′ = 4‐ClC₆H₄( 4 ); and R = CF₃, R′ = C₆H₅( 5 )) in equimolar ratio in refluxing benzene solution. Molecular weight measurements of these complexes show their monomeric nature in solution. Characterization of these compounds using elemental analyses, molecular weight measurements, and spectral studies (IR as well as NMR (¹H and ¹³C)) shows the monofunctional bidentate nature of the ligands and a hexacoordination around the central arsenic atom in these organoarsenic(V) derivatives. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:76–80, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20233     

Synthesis and structural characterization of new multiferrocenyl diyne ligands and their cobalt carbonyl complexes

New multiferrocenyl diyne ligands FcC(CH₃)₂Fc′–C≡C–C≡C–Fc [L ₁ ; Fc?=?C₅H₅FeC₅H₄; Fc′?=?C₅H₅Fe(1,3-disubstituted)C₅H₃], FcC(CH₃)₂Fc′–C≡C–C≡C–Fc′C(CH₃)₂Fc (L ₂ ) and their complexes [FcC(CH₃)₂Fc′–C≡C–C≡C–Fc][Co₂(CO)₆] _n [n?=?1, (1); n?=?2, (2)], [FcC(CH₃)₂Fc′–C≡C–C≡C–Fc′C(CH₃)₂Fc][Co₂(CO)₆] _n [n?=?1, (3); n?=?2, (4)] have been synthesized by the coupling reaction of terminal ferrocenylacetylene and the reaction of ligands L₁ and L₂ with Co₂(CO)₈. The composition and molecular structure of the ligands L₁ , L₂ and their cobalt complexes were characterized by element analysis, IR, ¹H(¹³C)NMR and MS. The electrochemical properties of compounds L₁ , L₂ , 1, 2, 3, 4 were studied by cyclic voltammetry(CV). The results of the electrochemical research reveal that all three ferrocenyl groups in L₁ become redox active centers, but there are only two (not four) ferrocenyl redox active centers in L₂ .     

Aluminum five‐ and six‐coordination in bis(acetylacetonato)aminoalkoxides

Reactions of bis(acetylacetonato)aluminum(III)‐di‐μ‐isopropoxo‐di‐isopropoxo aluminum(III), [(CH₃COCHCOCH₃)₂Al(μ‐OPrⁱ)₂Al(OPrⁱ)₂] with aminoalcohols, (HO R NR¹R²) in 1:1 and 1:2 molar ratios in refluxing anhydrous benzene yielded binuclear complexes of the types [(CH₃COCHCOCH₃)₂Al(μ‐OPrⁱ)₂Al(O R NR¹R²)(OPrⁱ)] and [(CH₃COCHCOCH₃)₂Al(μ‐OPrⁱ)₂Al(O R NR¹R²)₂] (R   (CH₂)₃ , R¹ = R² = H; R =  CH₂C(CH₃)₂ , R¹ = R² = H; R =  (CH₂)₂ , R¹ = H, R² =  CH₃; and R   (CH₂)₂ , R¹ = R² = CH₃), respectively. All these compounds are soluble in common organic solvents and exhibit sharp melting points. Molecular weight determinations reveal their binuclear nature in refluxing benzene. Plausible structures have been proposed on the basis of elemental analysis, molecular weight measurements, IR, NMR (¹H, ¹³C, and ²⁷Al), and FAB mass spectral studies. ²⁷Al NMR spectra show the presence of both five‐ and six‐coordinated aluminum sites. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:518–522, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10184     

Triphenylantimony(v) Derivatives of 2,2-Disubstituted Benzothiazoline Ligands: Synthetic and Spectroscopic Studies

The reactions of triphenylantimony(v) isopropoxide with 2,2-disubstituted benzothiazolines in a 1:2 molar ratio in refluxing benzene solution yielded the corresponding triphenylantimony(v) derivatives (1–5) of the type Ph₃Sb[SC₆H₄N: C(R)CH₂C(O)R']₂, [Where, R═CH₃, R'═CH₃(1); R═CH₃, R'═C₆H₅(2); R═CH₃, R'═4-CH₃C₆H₄(3); R═CH₃, R'═4-ClC₆H₄(4); and R═CF₃, R'═C₆H₅(5)]. All of these newly synthesized derivatives have been characterized by elemental analyses and molecular weight measurements as well as IR and NMR [¹H and ¹³C] spectral studies. On the basis of spectral data, seven-coordination around central antimony atom has been assigned to these derivatives.     

Fluorescent aluminum chelate complexes as modified precursors for nano-structured alumina

A series of new mononuclear heteroleptic derivatives of aluminum(III), {[(CH₃COCHCOCH₃)AlL] (1 and 4)}, {[(C₆H₅COCHCOC₆H₅)AlL] (2, 5, and 7)}, and {[(C₉H₆NO)AlL] (3 and 6)}, have been synthesized by reacting Al(OPrⁱ)₃ with tridentate Schiff base H₂L^x (H₂L¹ = C₁₃H₁₀BrNO₂; H₂L² = C₁₄H₁₃NO₃; H₂L³ = C₁₇H₁₃NO₂) and β-diketone/8-hydroxyquinoline (β-diketone = acetylacetone/dibenzoylmethane) in 1?:?1?:?1 stoichiometry using anhydrous benzene and ethanol. All the complexes were characterized by elemental analysis, FTIR, and NMR (¹H and ¹³C) spectral studies. Molecular structures obtained from single-crystal XRD of aqua 1 (1a) and DMSO coordinated 2 (2a) authenticate their existence. Further, nanostructured α-alumina was synthesized from 1 by well-established sol–gel method and was characterized by powder XRD, TEM, and EDX analyses.     

Synthesis,molecular structure and reactivity of new biferrocenylpropane derivatives

New biferrocenylpropane derivatives FcC(CH₃)₂Fc′-C≡C–R [Fc?=?C₅H₅FeC₅H₄; Fc′?=?C₅H₅FeC₅H₃, R?=?C₆H₅ (L ₁ ), Fc (L ₂ )] and their complexes [FcC(CH₃)₂Fc′-C≡C–R][Co₂(CO)₆] [R?=?C₆H₅ (1); R?=?Fc (2)] have been synthesized by the Castro-Stephens coupling reaction and the reactions of ligands L ₁ , L ₂ with Co₂(CO)₈. Compounds L ₁ , L ₂ , 1 and 2 were characterized by elemental analysis, IR, ¹H (¹³C) NMR and MS, and the molecular structures of ligands L ₁ , L ₂ were determined by X-ray single crystal analysis. The electrochemical properties of L ₁ , L ₂ , 1 and 2 demonstrate two or three resolved one-electron redox processes.     

Organoselenium/Tellurium-Bearing Macroacyclic and Cyclic Ligand Systems and Their Complexation Reactions

Abstract

A series of phenol-substituted acyclic Schiff bases, 2,6-{RE(CH₂) _n N═C(CH₃)}₂-C₆H₂(4-CH₃)(OH), (E = Te: R = C₆H₅, n = 2(L _a), 3(L _b); R = C₆H₄-4-OCH₃, n = 2(L _c), 3(L _d); E = Se: R = C₆H₅, n = 2(L _e), 3(L _f)), of the type E₂N₂O have been synthesized by condensation of 2,6-diacetyl-4-methylphenol with arylchalcogenoalkylamines. This ligand framework is useful for designing molecular complexes with a variety of coordination modes depending upon the nature of the central metal atom. The reactivity of the tellurium-bearing macroacyclics ligands towards Zn(II), Cd(II), and Hg(II) has been examined. The ligands L _a?L _d with Zn(II) and Cd(II), and only L _a and L _b with Hg(II) form complexes of composition M₂X₄L, (X = Cl or Br), whereas L _c and L _d with Hg(II) give products of composition HgBr₂L. The modes of ligand interaction with Zn(II) and Cd(II) are different than that with Hg(II).

Following a multistep reaction involving abstraction of bridged Br atoms and subsequent addition of more ligand, the mercury complex, Hg₂Br₄L has been used for developing metallocyclic system of the type [Hg₂Br₂L₂]²⁺. The latter has been found to encapsulate Zn(II) and Cd(II) to give multimetallic systems.     

Syntheses of phenoxo-bridged Zn(II) and metallamacrocyclic Hg(II) complexes of organochalcogen (Se,Te) substituted Schiff-bases: structure and DNA-binding studies of Zn(II) complexes

The coordination of organochalcogen (especially Se and Te) substituted Schiff-bases L¹H, L²H, L³H, and L⁴H toward Zn(II) and Hg(II) has been studied. Reactions of these ligands with ZnCl₂ in 1?:?1 molar ratio gave binuclear complexes [{2-[PhX(CH₂) _n N?=?C(Ph)]-6-[PhCO]-4-MeC₆H₂O}₂Zn₂Cl₂] (where X?=?Se, n?=?2 (1); X?=?Se, n?=?3 (2); X?=?Te, n?=?2 (3); and X?=?Te, n?=?3 (4)) with partial hydrolytic cleavage of proligands. In these complexes, two partially hydrolyzed ligand fragments coordinate tridentate (NOO) with two Zn's. Reaction of HgBr₂ with L¹H and L²H in 1?:?1 molar ratio gave monometallic complexes [C₆H₂(4-Me)(OH)[2,6-{C(Ph)?=?N(CH₂) _n Se(Ph)}₂HgBr₂]] (n?=?2 (5) or 3 (6)) and under similar conditions with L³H and L⁴H gave bimetallic complexes [C₆H₂(4-Me)(OH)[2,6-{C(Ph)?=?N(CH₂) _n Te(Ph)}₂Hg₂Br₄]] (n?=?2?(7) or 3 (8)) in which the ligands coordinate with metal through selenium or tellurium, leaving the imino nitrogen and phenolic oxygen uncoordinated. The proligands L¹H, L²H give 14- or 16-membered metallamacrocycles through Se–Hg–Se linkages and L³H, L⁴H give 16- or 18-membered metallamacrocycles through Te–Hg–Br–Hg–Te linkages. All the complexes were characterized by elemental analyses, ESIMS, FTIR, multinuclear NMR, UV-Vis, and conductance measurements. The redox properties of the complexes were investigated by cyclic voltammetry (CV). Complexes 1–4 exhibited ligand-centered irreversible oxidation processes. Complexes 5 and 6 showed metal-centered quasi-reversible single electron transfer, whereas dinuclear complexes 7 and 8 displayed two quasi-reversible, one-electron transfer steps. A single-crystal X-ray structure determination of 1 showed that the coordination unit is centrosymmetric with Zn(II) in square-pyramidal coordination geometry and the two square pyramids sharing an edge. The Zn?···?Zn separation is 3.232?Å. The DNA-binding properties of 1 and 3 with calf thymus DNA were explored by a spectrophotometric method and CV.     

Synthesis and characterization of heterobimetallic mixed-ligand complexes containing Zr(μ-OPri)2Al bridging units

Interesting varieties of heterobimetallic mixed-ligand complexes [Zr{M(OPrⁱ) _n }₂ (L)] (where M = Al, n = 4, L = OC₆H₄CH = NCH₂CH₂O (1); M = Nb, n = 6, L = OC₆H₄CH = NCH₂CH₂O (2); M = Al, n = 4, L = OC₁₀H₆CH = NCH₂CH₂O (3); M = Nb, n = 6, L = OC₁₀H₆CH = NCH₂CH₂O (4)), [Zr{Al(OPrⁱ)₄}₂Cl(OAr)] (where Ar = C₆H₃Me₂-2,5 (5); Ar = C₆H₂Me-4-Bu₂-2,6 (6), [Zr{Al(OPrⁱ)₄}₂(OAr)₂] (where Ar = C₆H₃Me₂-2,5 (7); Ar = C₆H₂Me-4-Bu₂-2,6 (8), [Zr{Al(OPrⁱ)₄}₃(OAr)] (where Ar = C₆H₃Me₂-2,5 (9); Ar = C₆H₃Me₂-2,6 (10), [ZrAl(OPrⁱ)_7-n (ON=CMe₂) _n ] (where n = 4 (11); n = 7 (12), [ZrAl₂(OPrⁱ)_10-n (ON=CMe₂) _n ] (where n = 4 (13); n = 6 (14); n = 10 (15) and [Zr{Al(OPrⁱ)₄}₂{ON=CMe(R)} _n Cl_2–n] [where n = 1, R = Me (16); n = 2, R = Me (17); n = 1, R = Et (18); n = 2, R = Et (19)] have been prepared either by the salt elimination method or by alkoxide-ligand exchange. All of these heterobimetallic complexes have been characterized by elemental analyses, molecular weight measurements, and spectroscopic (I.r., ¹H-, and ²⁷Al- n.m.r.) studies.     

Synthesis,structure, EPR,and DFT calculation on dinuclear paddle wheel Cu(II) complexes with bis-chelate rings

A series of diester-dicarboxylic acids, L¹H₂, L²H₂, L³H₂, L⁴H₂, and L⁵H₂ and their dinuclear Cu₂ complexes [Cu(L¹)CH₃CN]₂ (1), [Cu(L²)H₂O]₂ (2), [Cu(L³)CH₃CN]₂ (3), [Cu(L⁴)EtOH]₂ (4), and [Cu(L⁵)CH₃CN]₂ (5), were synthesized. The crystal structures obtained for 1, 2, and 4 and the density functional theory optimized structures for 2, 3, and 5 illustrated the formation of tetracarboxylate “paddle wheel” complexes. The phthalyl and diphenyl head groups and the spacer moieties were appropriately altered and the size of the chelate ring expanded from 15-membered in 1 to 21-membered in 5. The dinuclear units have strong Cu–Cu interaction with EPR spectra exploring spin coupled features.     

Homometallic glycolates containing hydroxyl functionality for anchoring another metal: synthesis and characterization of heterometallic alkoxide–glycolates of Ti and Zr incorporating Al and Nb

Reaction of Ti(OPrⁱ)₄ with 2-methyl-2,4-pentanediol [HOGOH, where G = CMe₂CH₂CH(Me)] in 1?:?3 M ratio under reflux afforded the monomeric [Ti(OGO)(OGOH)₂] (1), which on further reactions with [Al(OPrⁱ)₃] or [Nb(OPrⁱ)₅] in 1?:?1 and 1?:?2 M ratios afforded heterometallic derivatives, [Ti(OGO)₃{M(OPrⁱ)_n?2}] and [Ti(OGO)₃{M(OPrⁱ)_n?1}₂] [where M = Al (n = 3), Nb (n = 5)], respectively. Similar reactions of Zr(OPrⁱ)₄?PrⁱOH with a number of glycols [HOGOH, where G = CH(Me)CH(Me), CMe₂CMe₂, CMe₂CH₂CH(Me)] yielded dimeric [Zr₂(OGO)₂(OGOH)₄]. [Zr₂(OGO)₆{M(OPrⁱ)_n?2}₂] and [Zr₂(OGO)₄(OGOH)₂M(OPrⁱ)_n?2] [M = Al (n = 3), Ti (n = 4), Nb (n = 5)] were prepared by 1?:?2 and 1?:?1 reactions, respectively, of [Zr₂(OGO)₂(OGOH)₄] with Al(OPrⁱ)₃, Ti(OPrⁱ)₄, or Nb(OPrⁱ)₅. Surprisingly, a 1?:?2 reaction of [VO(OPrⁱ)₃] with 2,2-diethyl-1,3-propanediol in benzene followed a different reaction and produced a neutral tetranuclear derivative [V₄(O)₄(μ-OCH₂CEt₂CH₂O)₂(OCH₂CEt₂CH₂O)₄] (18). All of these derivatives were characterized by elemental analysis, molecular weight measurements, FT-IR, and ¹H NMR (and wherever possible, by ²⁷Al or ⁵¹V NMR) spectroscopic studies. The derivatives [Zr₂(OCMe₂CH₂CH(Me)O)₂(OCMe₂CH₂CH(Me)OH)₄] (9 and 18) were additionally characterized by single-crystal X-ray structure analysis.     

Bimetallic Rare Earth Alkyl Complexes Bearing Bridged Amidinate Ligands: Synthesis and Activity for L-Lactide Polymerization

Four novel bridged‐amidines H₂L {1,4‐R¹[C(=NR²)(NHR²)]₂ [R¹=C₆H₄, R²=2,6‐ⁱPr₂C₆H₃ (H₂L¹); R¹=C₆H₄, R²=2,6‐Me₂C₆H₃ (H₂L²); R¹=C₆H₁₀, R²=2,6‐ⁱPr₂C₆H₃ (H₂L³); R¹=C₆H₁₀, R²=2,6‐Me₂C₆H₃ (H₂L⁴)]} were synthesized in 65%–78% isolated yields by the condensation reaction of dicarboxylic acid with four equimolar amounts of amines in the presence of PPSE at 180°C. Alkane elimination reaction of Ln(CH₂SiMe₃)₃(THF)₂ (Ln=Y, Lu) with 0.5 equiv. of amidine in THF at room temperature afforded the corresponding bimetallic rare earth alkyl complexes (THF)(Me₃SiCH₂)₂LnL¹Ln(CH₂SiMe₃)₂(THF) [Ln=Y ( 1 ), Lu ( 2 )], (THF)(Me₃SiCH₂)₂LnL²Ln‐ (CH₂SiMe₃)₂(THF) [Ln=Y ( 3 ), Lu ( 4 )], (THF)(Me₃SiCH₂)₂YL³Y(CH₂SiMe₃)₂(THF) ( 5 ), (THF)(Me₃SiCH₂)₂YL⁴‐ Y(CH₂SiMe₃)₂(THF) ( 6 ) in 72% –80% isolated yields. These neutral complexes showed activity towards L‐lactide polymerization in toluene at 70°C to give high molecular weight (M>10⁴) and narrow molecular weight distribution (M_w/M_n≦1.40) polymers     

Nickel(II) complexes of ONS and ONN chelating thiosemicarbazones with triphenylphosphine co-ligands

Reactions of 5-bromo-2-hydroxy-benzaldehyde-S-R-4-R¹-thiosemicarbazones, [R, R¹ = H,H (L¹); CH₃, H (L²); H, C₆H₅ (L³); CH₃, C₆H₅ (L⁴)] with [Ni(PPh₃)₂Cl₂] in 1:1 molar ratio yielded complexes of general formula [Ni(L)(PPh₃)]. While the complexes of L¹ and L³ involve the ONS donor set of the thiosemicarbazone, the L² complexes utilize the ONN set. The reaction of L⁴ and the nickel salt gave the L³ complex by loss of the CH₃ group from the sulphur. The complexes were characterized by physico-chemical and spectroscopic methods. The structures of the L¹ and L² complexes have been determined by single crystal X-ray diffraction and a new coordination mode (ONN) of salicylaldehyde thiosemicarbazones has been identified. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Structure and properties of an oxalato-bridged dinickel(II) complex with a tetraazamacrocycle bearing an aminomethyl pendant arm, 5-aminomethyl-5R(S),12R(S)-dimethyl-1,4,8,11-tetraazacyclotetradecane

The oxalato-bridged dinickel(II) complex with the title ligand, [Ni₂(L ^a H)₂(μ-ox)](ClO₄)₂·2H₂O (1), was prepared and its structure was determined by X-ray crystallography, as well as that of the monomeric nickel(II) complex, [Ni(L ^a H)ox]ClO₄·3H₂O (2). In Complexes 1 and 2, the ligand, L ^a , is folded along the N(4)–Ni(1)–N(11) axis. The antiferromagnetic coupling between the two nickel(II) centers in 1 was revealed and the coupling constant, J?=??17.4?cm^?1, and g?=?2.11 were estimated. It was found that the oxalato-bridged dimer 1 was readily converted to the mononuclear cis-nickel(II) complex [NiL ^a (OH₂)](ClO₄)₂ (3a), in basic aqueous solution. In [NiL ^a (CH₃CN)]I₂ (3b), which was derived from 3a, the aminomethyl pendant arm is coordinated to the Ni(II) ion and L ^a is folded along the N(1)–Ni(1)–N(8) axis.     

Synthesis and characterization of cyclopalladated complexes of benzylamine by IR and NMR spectroscopy studies

The chloro-bridged dimer [Pd(μ-Cl)(C₆H₄CH₂NH₂-κ²-C,N)]₂ reacts with PPh₂Et, P(p-tolyl)₃, AsPh₃, piper (piper =?C₅H₁₀N) and Py in dichloromethane at room temperature for 24 h in a one-to-two molar ratio and undergoing bridge-splitting reactions to give [PdCl(C₆H₄CH₂NH₂–κ²-C,N)L] (L =?PPh₂Et (1a), P(p-tolyl)₃ (1b), AsPh₃ (1c), piper (1d), C₆H₄CH₂NH₂ (3e) and Py (1f)). Complex 1f in THF at room temperature reacts with a stoichiometric amount of TlTfO (thallium triflate, TfO=CF₃SO₃) and Py (molar ratio 1 : 1 : 1) to afford [Pd(C₆H₄CH₂NH₂)(Py)₂]TfO (2). Infrared and NMR spectroscopies allow unambiguous characterization of these products.