Syntheses and characterization of a new class of zirconia precursors of oxime-modified zirconium(IV) isopropoxide

Some oxime modified complexes of the type [Zr{OPrⁱ}_4?n{L}_n] {where, n = 1–4 and LH=(CH₃)₂C=NOH (1–4) and C₉H₁₆C=NOH (5–8)} have been synthesized by the reaction of [Zr(OPrⁱ)₄·PrⁱOH] with oximes, in anhydrous refluxing benzene. These synthesized complexes were characterized by elemental analyses, molecular weight measurements, ESI-mass, FT-IR and NMR (¹H and ¹³C{¹H}) spectral studies. The ESI-mass spectral studies indicate dimeric nature for [Zr{OPrⁱ}₂{ONC(CH₃)₂}₂] (2), [Zr{OPrⁱ}₃{ONC₁₀H₁₆}] (5) and [Zr{OPrⁱ}{ONC₁₀H₁₆}₃] (7) and monomeric nature for [Zr{ONC₁₀H₁₆}₄] (8). Oximato ligands appear to bind the zirconium in side on manner in all the complexes. Thermogravimetric curves of (2) and (8) exhibit multi-step decomposition with the formation of ZrO₂, under nitrogen atmosphere. Sol–gel transformations of precursors (5), (6), (7) and (8) in organic medium, yielded nano-sized tetragonal phase of zirconia samples (a), (b), (c) and (d), respectively, on sintering at ~600 °C. All these samples were characterized by Powder XRD patterns and EDX analyses. Surface morphologies of these samples were investigated by SEM images.     

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     

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 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.     

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.     

The alkoxides of zirconium and hafnium: direct electrochemical synthesis and mass-spectral study. Do “M(OR)4”, where M=Zr,Hf, Sn,really exist?

The direct electrochemical synthesis of zirconium (1a) and hafnium (1b) alkoxides, M(OPrⁱ)₄·PrⁱOH, Zr(OBuⁱ)₄·BuⁱOH (4a) and M(OR)₄, where R=Et (2a,b), Buⁿ (3a), Bu^s (5a), C₂H₄OMe (6a,b) has been carried out by anodic oxidation of metals in anhydrous alcohols in the presence of LiCl as a conductive additive to give quantitative yields. The solubility polytherms and dissociation pressure of1a,b have been investigated. It has been proved by means of chemical analysis, X-ray powder, and IR spectral studies that the desolvation of 1a,b and Sn(OPrⁱ)₄·PrⁱOH (1c) is accompanied by the formation of amorphous oxocompounds M₃O(OPr_i)₁₀. On the basis of¹H NMR data it has been proved that the structure of the latter is analogous to that of known triangular cluster molecules M₃(₃-O)(₃-OR)(-OR)₃(OR)₆, where M=Mo, W, U. Mass-spectral data and the determined physicochemical characteristics of1–5 permit to conclude that the samples of composition M(OR)₄, where M=Zr, Hf, and2,3,5 contain tri- and tetranuclear oxocomplexes M₃O(OR)₁₀ and M₄O(OR)₁₄ respectively, along with Zr(OR)₄ oligomers of different molecular complexity.Deceased.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 752–760, April, 1995.     

A Sr(II)-Zr(IV)-Cd(II) Alkoxide Cluster: Synthesis and X-Ray Structure of [{Cd(OPri)3}Sr{Zr2(OPri)9}]2

New heterotrimetallic alkoxide [{Cd(OPrⁱ)₃}Sr{Zr₂(OPrⁱ)₉}]₂ (1) is obtained quantitatively in an anion-exchange reaction involving well-characterised iodide heterobimetallic alkoxide ICd{Zr₂(OPrⁱ)₉} and the alkali metal reagent KSr(OPrⁱ)₃. The formation of 1 is accompanied with an exchange of metals (Cd(II) and Sr(II)) between the constituting fragments (‘Cd{Zr₂(OPrⁱ)₉}⁺’ and ‘Sr(OPrⁱ)₃ ^?’) and the chelating Zr₂(OPrⁱ)₉ ^? anion, in 1, coordinates to Sr²⁺ in contrast to the precursor ICdZr₂(OPrⁱ)₉ where it is bound to Cd²⁺. The heterotrimetallic nature of 1 is unambiguously established by multinuclear (¹H, ¹³C and ¹¹³Cd) NMR spectral data and a single crystal X-ray diffraction analysis.     

Synthesis and characterization of 2-hydroxy-pyridine modified Group 4 alkoxides

The reaction of Group 4 metal alkoxides ([M(OR)₄]) with the potentially bidentate ligand, 2-hydroxy-pyridine (2-HO-(NC₅H₄) or H-PyO), led to the isolation of a family of compounds. The products isolated from the reaction of [M(OR)₄] [where M = Ti, Zr, or Hf; OR = OPrⁱ (OCH(CH₃)₂), OBu^t (OC(CH₃)₃), or ONep (OCH₂C(CH₃)₃] under a variety of stoichiometries with H-PyO were identified by single crystal X-ray diffraction as [(OPrⁱ)₂(PyO-κ²(O,N))Ti(μ-OPrⁱ)]₂ (1), [(ONep)₂Ti(μ(O)-PyO-κ²(O,N))₂(μ-ONep)Ti(ONep)₃] (2), [(ONep)₂Ti(μ(O)-PyO-κ²(O,N))(η¹(N),μ(O)-PyO)(μ-O)Ti(ONep)₂]₂ (2a), [H][(PyO-κ²(O,N))(η¹(O)-PyO)Ti(ONep)₃] (3), [(OR)₂Zr(μ(O)-PyO-κ²(O,N))₂(μ-OR)Zr(OR)₃] (OR = OBu^t (4), ONep (5)), [(OR)₂Zr(μ(O,N)-PyO-κ²(O,N))₂(μ(O,N)-PyO)Zr(OR)₃] (OR = OBu^t (6), ONep (7)), [[(OBu^t)₂Zr(μ(O)-PyO-(κ²(N,O))(μ(O,N)-PyO)₂Zr(OBu^t)](μ₃-O)]₂ (6a), [[(ONep)(PyO-κ²(N,O))Zr(μ(O,N)-PyO-κ²(N,O))₂(μ(O)-PyO-κ²(N,O))Zr(ONep)](μ₃-O)]₂ (7a), [(OBu^t)(PyO-κ²(O,N))Zr(μ(O)-PyO-κ²(O,N))₂((μ(O,N)-PyO)Zr(OBu^t)₃] (8), [(OBu^t)₂Hf(μ(O)-PyO-κ²(N,O))₂(μ-OBu^t)Hf(OBu^t)₃] (9), [(OR)₂ M(μ(O)-PyO-κ²(N,O))₂(μ(O,N)-PyO)M(OR)₃] (OR = OBu^t (10), ONep (11)), and [(ONep)₃Hf(μ-ONep)(η¹(N),μ(O)-PyO)]₂Hf(ONep)₂ (12)·tol. The structural diversity of the binding modes of the PyO led to a number of novel structure types in comparison to other pyridine alkoxy derivatives. The majority of compounds adopt a dinuclear arrangement (1, 2, 4–11) but oxo-based tetra- (2a and 7a), tri- (12), and monomers (3) were observed as well. Compounds 1–12 were further characterized using a variety of analytical techniques including Fourier Transform Infrared Spectroscopy, elemental analysis, and multinuclear NMR spectroscopy.     

Synthesis of the first examples of stable heterometallic isopropoxides of an organometallic RSn(IV) moiety

Five-, six-, and seven-coordinate volatile butyltin(IV) heterobimetallic derivatives, respectively of the types, [BuSn{(μ-OPrⁱ)₂Al(OPrⁱ)₂}Cl₂] (1), [BuSn{(μ-OPrⁱ)₂Al(OPrⁱ)₂}₂Cl] (2), and BuSn{(μ-OPrⁱ)₂M(OPrⁱ)_x − 2}₃ (3:M = Al (x = 4); 4:M = Ga (x = 4); 5:M = Nb (x = 6)) have been synthesized by the reactions of BuSnCl₃ with potassium tetraisopropoxoaluminate in 1:1, 1:2, and 1:3 molar ratios. Replacement reactions of chloride in (1) and (2) with appropriate alkoxometallate (tetraisopropoxoaluminate, tetraisopropoxogallate, or hexaisopropoxoniobate) ligands result in the formation of novel BuSn(IV) heterotri- and tetra-metallic derivatives. All of these derivatives have been characterized by elemental analyses, molecular weight measurements, and spectroscopic (IR, ¹H, ²⁷Al, and ¹¹⁹Sn NMR) studies. Based on these studies, plausible structures for the new derivatives involving bidentate ligation of the alkoxometallate ligands have been suggested.     

Novel platinum(II) and (IV) complexes of naphthaldimine schiff bases

Naphthaldimines containing N₂O₂ donor centers react with platinum(II) and (IV) chlorides to give two types of complexes depending on the valence of the platinum ion. For [Pt(II)], the ligand is neutral, [(H₂L¹)PtCl₂]·3H₂O (1) and [(H₂L³)₂Pt₂Cl₄]·5H₂O (3), or monobasic [(HL²)₂Pt₂Cl₂]·2H₂O (2) and [(HL⁴)₂Pt]·2H₂O (4). These complexes are all diamagnetic having square-planar geometry. For [Pt(IV)], the ligand is dibasic, [(L¹)Pt₂Cl₄(OH)₂]·2H₂O (5), [(L²)Pt₃Cl₁₀]·3H₂O (6), [(L³)Pt₂Cl₄(OH)₂]·C₂H₅OH (7) and [(L⁴)Pt₂Cl₆]·H₂O (8). The Pt(IV) complexes are diamagnetic and exhibit octahedral configuration around the platinum ion. The complexes were characterized by elemental analysis, UV-Vis and IR spectra, electrical conductivity and thermal analyses (DTA and TGA). The molar conductances in DMF solutions indicate that the complexes are non-ionic. The complexes were tested for their catalytic activities towards cathodic reduction of oxygen.     

Supramolecular organotin(IV) dithiocarboxylates as potential antimicrobial agents

A series of tri-, chlorodi-, and diorganotin(IV) derivatives of 4-(2-methoxyphenyl)piperazine-1-carbodithioate (L) {R?=?n-C₄H₉ (1), C₆H₁₁ (2), CH₃ (3) and C₆H₅ (4)}, (n-C₄H₉)₂SnClL (5) and R₂SnL₂ {R?=?n-C₄H₉ (6), C₂H₅ (7), CH₃ (8)} have been synthesized by refluxing organotin(IV) chlorides with the ligand-salt in the appropriate molar ratio. Elemental analysis, Raman, IR, multinuclear NMR (¹H, ¹³C and ¹¹⁹Sn), mass spectroscopic, and single-crystal X-ray crystallographic studies were undertaken to elucidate the structures of the new compounds both in solution and in the solid state. The X-ray diffraction work reveals supramolecular structures for 4 and 6, with distorted trigonal-bipyramidal and distorted octahedral geometries around Sn, respectively. The ligand and several of the new compounds are good antimicrobial agents.     

Synthesis and Characterization of Some Unique Heterocyclic Derivatives Containing Aluminium(III) Atoms in 4- and 6-Co-Ordination States∶ Reaction of Bis(β-Diketonato) Aluminium (III)-DI-μ-Isopropoxo-DI-Isopropoxo Aluminium(III) with Triphenylsilanol and Diphenylsilanediol

Reactions of bis ( g -diketonato) aluminium(III)-di- w -isopropoxo-di-isopropoxo-aluminium (III), [CH₃COCHCOR)2Al( w -OPrⁱ)₂Al(OPrⁱ) ₂], with triphenylsilanol, Ph₃SiOH, in 1:1 and 1:2 molar ratios and with diphenylsilanediol, Ph₂Si(OH)₂, in a 1:1 molar ratio, have resulted in the synthesis of [(CH₃COCHCOR)₂Al( w -OPrⁱ)₂Al(OSiPh₃)(OPrⁱ)], [(CH₃COCHCOR)₂Al( w -OPrⁱ)₂Al(OSiPh₃)₂] and [(CH₃COCHCOR)₂Al( w -OPrⁱ)₂Al(OSiPh₂O], respectively. These are soluble in a variety of organic solvents ( e.g. , benzene, chloroform and dimethylsulfoxide) and show dinuclear behaviour in chloroform. These derivatives have been characterized by elemental analyses, molecular weight measurements, IR and NMR (¹H, ¹³C and ²⁷Al) studies.     

Glycol modified titanosiloxane as molecular precursor for homogenous titania–silica material: synthesis and characterization

Ti(OPrⁱ)₄ reacts with HOSi(O^tBu)₃ in anhydrous benzene in 1:1 and 1:2 molar ratios to afford alkoxy titanosiloxane precursors, [Ti(OPrⁱ)₃{OSi(O^tBu)₃}] (A) and [Ti(OPrⁱ)₂{OSi(O^tBu)₃}₂] (B), respectively. Further reactions of (A) or (B) with glycols in 1:1 molar ratio afforded six complexes of the types [Ti(OPrⁱ)(O–G–O){OSi(O^tBu)₃}] (1A–3A) and [Ti(O–G–O){OSi(O^tBu)₃}₂] (1B–3B), respectively [where G = (CH₂)₂ (1A, 1B); (CH₂)₃ (2A, 2B) and {CH₂CH₂CH(CH₃)} (3A, 3B)]. Both (A) and (B) are liquids while all the other products are viscous liquids which get solidified on ageing. Cryoscopic molecular weight measurements of the fresh products indicate their monomeric nature. FAB mass studies of (A) and (B) also indicate monomeric nature. However, FAB mass spectra of the two representative solids (1A) and (2B) suggest dimeric behavior of the glycolato derivatives. (A) distills at 85 °C/5 mm while other products get decomposed even under reduced pressure. TG analyses of (A), (B), (1A), and (1B) suggest formation of titania–silica materials at 200 °C for (A) and (B) and 350 °C for (1A) and (1B). The products have been characterized by elemental analyses, FTIR and ¹H, ¹³C & ²⁹Si-NMR techniques. All these products are soluble in common organic solvents indicating a homogenous distribution of the components on the molecular scale. The Si/Ti ratio of the oxide may be controlled easily by the composition of the starting precursors. Hydrolysis of the glycol modified derivative, (1A) by the Sol–Gel technique affords the desired homogenous titania–silica material, TiO₂·SiO₂ in nano-size while, the precursor (A) yields a non-stiochiometric silica doped titania material. However, pyrolysis of (A) yields nano-sized crystallites of TiO₂·SiO₂. All these materials were characterized by FTIR, powder XRD patterns, SEM images, and EDX analyses.     

Heterotri- and -tetrametallic alkoxides of chromium(III) containing aluminium(III), gallium(III) and niobium(V)

CrCl₃ · 3THF reacts with two equivalents of potassium alkoxometallates K{M(OPr ⁱ ) _x } [M = Al(A), Ga(B), x = 4; M = Nb(C), x = 6] to give heterobimetallic chloride isopropoxides [Cr{M(OPr ⁱ ) _x }₂Cl(THF)] [M = Al(A – 1), Ga(B – 1), and Nb(C – 1)], in which the replacement of the chloride with an appropriate alkoxometallate (tetraisopropoxoaluminate, tetraisopropoxogallate, or hexaisopropoxoniobate) results in the formation of novel heterotrimetallic derivatives. The 'single pot synthesis of an heterotetrametallic isopropoxide [Cr{Nb(OPr ⁱ )₆}{Al(OPr ⁱ )₄}{Ga(OPr ⁱ )₄}] (7) has been carried out by the sequential addition of (A), (B), and (C) to a benzene suspension of CrCl₃ · 3THF. Alcoholysis of [Cr{Al(OPr ⁱ )₄}₂{Nb(OPr ⁱ )₆}] (1) and [Cr{Al(OPr ⁱ )₄}₂{Ga(OPr ⁱ )₄}] (5) with t-BuOH has also been studied and the derivatives characterized by elemental analyses, molecular weight determinations, spectroscopic [Electronic, i.r., ²⁷Al-n.m.r.] and magnetic susceptibility studies.     

2-(2-Hydroxy-4-methoxybenzoyl)benzoic acid derivatives of Group 4 metal alkoxides

Continued exploration of the coordination behavior of derivatives of 2-benzophenone-based ligands with metal alkoxides ([M(OR)₄]) was undertaken from the reaction of 2-(2-hydroxy-4-methoxybenzoyl)benzoic acid (H₂-OBzA) with a series of Group 4 precursors. The products of these reactions were identified as: [(OR)₂Ti(μ-(c,c-OBzA))]₂ (OR?=?OCHMe₂ (OPrⁱ; 1 ?2tol); OCMe₃ (OBu^t; 2 ?THF); OCH₂CMe₃ (ONep; 3)), [[(OPrⁱ)₃Ti(μ-OPrⁱ)Ti(OPrⁱ)₂]₂(μ-(μ_c,μ-OBzA))₂]₂ (4), [(ONep)₃Zr(μ-ONep)₂Zr(ONep)₂]₂(μ-(c,μ-OBzA)₂) (5 ?tol), [(py)(OBu^t)₃Zr]₂(μ-(c,c-OBzA)) (6), [(OBu^t)₂Hf(μ-OBu^t)]₂(μ-(c,η¹-OBzA)) (7) where ‘c’?=?chelating or η²; ‘μ’?=?bridging or η¹,η¹(O,O’); and μ_c?=?bridging chelating or η¹,η¹(O,O’); η^2?:?η¹. The metal centers for each of these compounds adopt a pseudo-octahedral geometry employing the OBzA ligand in numerous binding modes. The different functional oxygens (carboxylate, hydroxyl, and carbonyl) were employed in a variety of coordination modes for 1–7. The complexity of these OBzA-modified compounds is driven by a combination of the coordination behavior of the OBzA moieties, the size of the metal cation, and the pendant chain of the OR ligand. Solution NMR indicates a complex structure exists in solution that was considered to be consistent with the solid-state structure.     

Homo- and hetero-dinuclear derivatives of aluminium containing Schiff-base ligands: synthesis,characterization and antibacterial activity of mononuclear derivative of aluminium

Reactions of Al(OPrⁱ)₃ with LH₂ =?[R′C(NYOH)CHC(R)OH] R=R′=CH₃, Y =?(CH₂)₂ (L¹H₂); R =?CH₃, R′ =?C₆H₅, Y =?(CH₂)₂ (L²H₂); R =?R′ =?CH₃, Y =?(CH₂)₃ (L³H₂); R =?CH₃, R′ =?C₆H₅, Y =?(CH₂)₃ (L⁴H₂), in 1 : 2 molar ratio give mononuclear derivatives of aluminium AlLLH (1a–1d). Equimolar reactions of AlLLH with M(OPrⁱ)₃ (M =?Al and B) yield homo- and hetero-dinuclear derivatives AlLLM(OPrⁱ)₂ (M=Al=2a–2d M=B=3a–3d). Reaction of 2a with L¹H₂ affords AlL¹L¹AlL¹ (4). All these derivatives have been characterized by elemental analysis, molecular weight measurements and plausible structures have been suggested on the basis of IR, NMR [¹H, ¹³C, ²⁷Al and ¹¹B] spectral data and FAB-mass studies of 2b and 3b. Schiff base L¹H₂ and its mononuclear derivative with aluminium (AlL¹L¹H) have been screened for their antibacterial activity against Escherischia coli and Bacillus subtilis.     

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     

Synthesis and crystal structure of diorganotin(IV) complexes with pyruvic acid benzoylhydrazone and pyruvic acid salicylhydrazone

Six diorganotin esters of Schiff-base ligands formulated as [R₂SnLY]₂, where L₁ is C₆H₅CON₂C(CH₃)CO₂ with Y?=?CH₃CH₂OH, R?=?mClC₆H₄CH₂ (1), oFC₆H₄CH₂ (2), pFC₆H₄CH₂ (3) and L₂ is 2-HOC₆H₄CON₂C(CH₃)CO₂ with Y?=?CH₃OH, R?=?oFC₆H₄CH₂ (4), pFC₆H₄CH₂ (5), mClC₆H₄CH₂ (6) have been prepared and characterized by elemental analysis, IR, ¹H and ¹¹⁹Sn NMR spectra. The crystal structures of complexes 1 and 4 have been determined by X-ray single crystal diffraction. The structure analyses reveal that the Sn atom in both 1 and 4 is seven-coordinate in distorted pentagonal bipyramid geometries with a planar SnO₄N unit and two apical aryl carbon atoms, thus forming a dimeric molecule, which sits on a crystallographic center of symmetry. Intramolecular or intradimeric hydrogen bonds contribute to the stability and compactness of the crystal structures.