Neutral penta-coordinated diorganotin(IV) complexes derived from ortho-aminophenol Schiff bases: Synthesis, characterization and molecular structures

The one pot reactions carried among ortho-aminophenol, R₂SnO (R = Me or Ph) and acetyl acetone, 2-hydroxyacetophenone and 2-hydroxy-3-methylacetophenone led to six new diorganotin(IV) compounds Me₂SnL1 (1), Ph₂SnL1 (2), Me₂SnL2 (3) Ph₂SnL2 (4), Me₂SnL3 (5) and Ph₂SnL3 (6) (H2L1 = 2-(3-hydroxy-1-methyl-but-2-enylideneamino)-phenol, H2L2 and H2L3 = 2-[1-(2-hydroxyaryl)alkylideneamino]-phenol) in good yields. Combination of IR, ¹H, ¹³C and ¹¹⁹Sn NMR and X-ray diffraction techniques along with elemental analyses evidenced the formation of penta-coordinated monomeric species. The crystal structures of ligand H2L1 and complexes 1, 3 and 4 were determined by single crystal X-ray diffraction study. In the solid state, the ligand H2L1 exists as keto-enamine tautomeric form. There are N-H…O intra-molecular hydrogen bonds between amine and carbonyl groups. Diorganotin(IV) complexes 1, 3 and 4 are monomers with TBP (trigonal bipyramidal) geometry surrounding the tin atom. The O, N, O- tridentate ligand places its two oxygen donating atoms in the axial positions, and the nitrogen atom occupies one equatorial position. The two R groups attached to tin occupy the other two equatorial positions. The solution structures were predicted by ¹¹⁹Sn NMR spectroscopy.     

Berry exchange coordinate geometry in 3-methyl-2-hydroxycyclopenten-1-one tin esters

Three new penta- and hexacoordinated tin compounds (1-3) were prepared from PhSnCl₃, Ph₂SnCl₂ and Ph₃SnOH and 3-methyl-2-hydroxy-2-cyclopenten-1-one (L). Compounds 1-3 were characterized by IR, mass spectra, elemental analysis, ¹H, ¹³C, and ¹¹⁹Sn NMR. The ligand acts as a bidentate giving the tin esters and coordinating the tin by the carbonyl group. Compound 1 (PhSnCl₂L · EtOH) has an hexacoordinated tin atom, with an octahedral distorted geometry, which is a stereogenic center. Compounds 2 (Ph₂SnClL) and 3 (Ph₃SnL) have pentacoordinated tin atoms. The structures were determined by X-ray diffraction analyses. In the solid state 1 presents a racemic pair, linked by strong hydrogen bonds and 2 and 3 “Berry exchange coordinate” geometry.     

Syntheses, structures and intermolecular interactions of tetraorganoammonium, -phosphonium and -stibonium dimethyl- and diphenyltetrahaloantimonates

The syntheses and spectroscopic (NMR, MS) investigations of the antimonates [Ph₄P]⁺[Me₂SbCl₄]⁻ (1), [Me₄Sb]⁺[Me₂SbCl₄]⁻ (2), [Et₄N]⁺[Ph₂SbCl₄]⁻ (3), [Bu₄N]⁺[Ph₂SbCl₄]⁻ (4), [Me₄Sb]⁺[Ph₂SbCl₄]⁻ (5), [Et₃MeSb]⁺[Ph₂SbCl₄]⁻ (6), [Et₄N]⁺[Ph₂SbF₄]⁻ (7) and [Et₄N]⁺[Ph₂SbBr₄]⁻ (8) are reported. Halogen scrambling reactions of Et₄NBr or Ph₄EBr (E = P, Sb) with R₂SbCl₃ (R = Me, Ph) produce mixtures of compounds from which crystals of [Et₄N]⁺[Ph₂SbBr_1.24Cl_2.76]⁻ (9), [Et₄N]⁺[Ph₂SbBr_2.92Cl_1.08]⁻ (10) or [Ph₄Sb]⁺[Me₂SbCl₄]⁻ (11) were isolated. The crystal and molecular structures of 1 and 3-11 are reported.     

Triorganotin(IV) derivatives of 7-amino-2-(methylthio)[1,2,4]triazolo[1,5-a]pyrimidine-6-carboxylic acid. Synthesis, spectroscopic characterization, in vitro antimicrobial activity and X-ray crystallography

Triorganotin(IV) complexes of the 7-amino-2-(methylthio)[1,2,4]triazolo[1,5-a]pyrimidine-6-carboxylic acid (HL), Me₃SnL(H₂O), (1), [n-Bu₃SnL]₂(H₂O), (2), Ph₃SnL(MeOH), (3), were synthesized by reacting the amino acid with organotin(IV) hydroxides or oxides in refluxing methanol. The complexes have been characterized by elemental analysis, ¹H, ¹³C and ¹¹⁹Sn NMR, IR, Raman and ¹¹⁹Sn Mössbauer spectroscopic techniques. Single crystal X-ray diffraction data were obtained for compounds (2) and (3). Ph₃SnL(MeOH) presents a trigonal bipyramidal structure with the organic groups on the equatorial plane and the axial positions occupied by a ligand molecule, coordinated to tin through the carboxylate, and a solvent molecule, MeOH. A similar structure is proposed for Me₃SnL(H₂O) on the basis of analytical and spectroscopic data. The tributyltin(IV) derivative, [n-Bu₃SnL]₂(H₂O), is characterized by two different tin sites with similar tbp geometry featured by butyl groups on the equatorial plane. Sn(1) and Sn(2) atoms are axially bridged by a ligand molecule binding through the N(4) and the carboxylate group; the two coordination spheres are saturated by another ligand molecule, binding the metal through the carboxylate group, and a water molecule, respectively. Antimicrobial tests on compounds 1 and 2 showed in vitro activity against Gram-positive bacteria.     

Organotin esterification of (E)-3-(3-fluoro-phenyl)-2-(4-chlorophenyl)-2-propenoic acid: synthesis, spectroscopic characterization and in vitro biological activities. Crystal structure of [Ph3Sn(OC(O)C(4-ClC6H4) = CH(3-FC6H4))]

Nine organotin esters, Me₂SnL₂1, Me₃SnL 2, n-Bu₂SnL₂3, n-Bu₃SnL 4, Ph₃SnL 5, (PhCH₂)₂SnL₂6, [(Me₂SnL)₂O]₂7, Et₂SnL₂8 and n-Oct₂SnL₂9, of (E)-3-(3-fluorophenyl)-2-(4-chlorophenyl)-2-propenoic acid, HL have been synthesized and characterized by elemental analysis, IR, Multinuclear NMR (¹H, ¹³C and ¹¹⁹Sn) and mass spectrometry. The geometry around the tin atom has been deduced and compared both in solution and solid states. The crystal structure of compound 5 has been determined by X-ray single crystal analysis, which shows a tetrahedral geometry around the tin atom with space group . These compounds have also been screened for bactericidal, fungicidal activities and cytotoxicity data.     

Synthesis,spectroscopic characterization,X-ray crystal structure,biological screening and catalytic studies of organotin(IV) carboxylates of 3-(4-cyanophenyl) acrylic acid

A series of six organotin(IV) carboxylates [Me₂SnL₂] (1), [n-Bu₂SnL₂] (2), [n-Oct₂SnL₂] (3), [Me₃SnL] (4), n-Bu₃SnL (5) and [Ph₃SnL] (6), where L = 3-(4-cyanophenyl) acrylic acid have been synthesized and characterized by elemental analysis, FT-IR and NMR (¹H, ¹³C). The complex (4) was also analyzed by single crystal X-ray analysis which showed distorted trigonal bipyramidal geometry with polymeric bridging behavior. The complexes 1–6 were screened for antimicrobial activities and cytotoxicity. The results showed significant activity with few exceptions. The catalytic activity of complexes was assessed in transesterification reaction of Brassica campestris oil (triglycerides) to produce biodiesel (fatty acid methyl esters). The results showed that triorganotin(IV) complexes exhibited good catalytic activity than their di-analogues.     

Self-assembly of diorganotin(IV) 2-{[(E)-1-(2-oxyaryl)alkylidene]amino}acetates: An investigation of structures by X-ray diffraction, solution and solid-state tin NMR, and electrospray ionization MS

The diorganotin(IV) compounds, [Me₂SnL²(OH₂)]₂ (1), [ⁿBu₂SnL²(OH₂)]₂ (2), [ⁿBu₂SnL¹]₃ · 0.5C₃H₆O (3), [ⁿBu₂SnL³]₃ · 0.5C₆H₆ (4) and [Ph₂SnL³]_n · 0.5C₆H₆ (5) (L = carboxylic acid residue, i.e., 2-{[(E)-1-(2-oxyaryl)alkylidene]amino}acetate), were synthesized by treating the appropriate diorganotin(IV) dichloride with the potassium salt of the ligand in anhydrous methanol.The reaction of Ph₂SnL² (L = 2-{[(E)-1-(2-oxyphenyl)ethylidene]amino}acetate) with 1,10-phenanthroline (Phen) yielded a 1:1 adduct of composition, [Ph₂SnL²(Phen)] (6).The crystal structures of 1-6 were determined.The crystal of 1 is composed of centrosymmetric dimers of the basic Me₂SnL²(OH₂) moiety, where the two Sn-centres are linked by two asymmetric Sn-O?Sn bridges involving the carboxylic acid O atom of the ligand and a long Sn?O distance of 3.174(2) Å.The dimers are further linked into columns by hydrogen bonds.The coordination geometry about the Sn atom is a distorted pentagonal bipyramid with the two methyl groups in axial positions.The structure of 2 is similar.The same Sn atom coordination geometry is observed in compound 3, which is a cyclic trinuclear[ⁿBu₂SnL¹]₃ compound. Each Sn atom is coordinated by the phenoxide O atom, one carboxylate O atom and the imino N atom from one ligand and both the exo- and endo-carboxylate O atoms (mean Sn-O(exo): 2.35 Å; Sn-O(endo): 2.96 Å) from an adjacent ligand to form the equatorial plane, while the two butyl groups occupy axial positions. Compound 4 was found to crystallize in two polymorphic forms. The Sn-complex in both forms has a trinuclear [ⁿBu₂SnL³]₃ structural motif similar to that found in 3. In compound 5, distorted trigonal bipyramidal Ph₂SnL³ units are linked into polymeric cis-bridged chains by a weak Sn?O interaction (3.491(2) Å) involving the exocyclic O atom of the tridentate ligand of a neighboring Sn-complex unit. This interaction completes a highly distorted octahedron about the Sn atom, where the weakly coordinated exocyclic O atom and one phenyl group are trans to one another. In contrast, a monomeric distorted pentagonal bipyramidal geometry is found for adduct 6 where the Sn-phenyl groups occupy the axial positions. The solution and solid-state structures are compared by using ¹¹⁹Sn NMR chemical shift data. Compounds 1-6 were also studied using ESI-MS and their positive- and negative-ions mass fragmentation patterns are discussed.     

Synthesis and characterization of organotin(IV) compounds with Schiff base of o-vanillin-2-thiophenoylhydrazone

Seven Schiff base adducts of organotin(IV), RSnLCl₂, which L is o-vanillin-2-thiophenoylhydrazone, and R is n-C₄H₉ (1), Me (2), Ph (3), and [R₂SnL], which L is o-vanillin-2-thiophenoylhydrazone, R is n-C₄H₉ (4), Me (5), Ph (6), PhCH₂ (7) have been synthesized. Those products were characterized by elemental analysis, IR, ¹H, ¹³C and ¹¹⁹Sn NMR spectra. The crystal and molecular structures of compounds 1, 4, and 6 have been determined by X-ray single crystal diffraction. In the crystal of compound 1 the tin atom is rendered six-coordinate in a distorted octahedral configuration by coordinating with the N atom of the Schiff base ligand, in compounds 4 and 6 the central tin atoms are five-coordinate in distorted trigonal-bipyramidal geometry and the comparison of the IR spectra reveal that disappearance of the bands assigned to carboxyl unambiguously conforms the ligand coordinate with the tin atom in enol form.     

Synthesis, characterization, and molecular structures of di- and triorganotin(IV) complexes with 9-anthracenecarboxylic acid: The structural diversity in organotin 9-anthracenecarboxylates

The di- and triorganotin(IV) derivatives of anthracenecarboxylic acid, Ph₂MeSnOC(O)C₁₄H₉ (2), Me₃SnOC(O)C₁₄H₉ (3), Me₂Sn[OC(O)C₁₄H₉]₂ · CH₃OH (4) Ph₃SnOC(O)C₁₄H₉ · CH₃OH (5), Ph₂EtSnOC(O)C₁₄H₉ (6), Ph₂Sn[OC(O)(C₁₄H₉)]₂ (7) and PhMe₂SnOC(O)C₁₄H₉ (8) were synthesized by the reaction of Ph₂MeSnI, Me₃SnCl, Me₂SnCl₂, Ph₃SnCl, Ph₂EtSnI, Ph₂SnCl₂, and PhMe₂SnI with 9-anthracenecarboxylic acid, respectively, with the aid of potassium iso-propoxide. All complexes were characterized by elemental analysis, mass spectrometry, IR, ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopes. The molecular structures of complexes 2, 3 and 4 were determined by single crystal X-ray analysis. The X-ray structures reveal that complex 2 and 3 adopt a polymeric trans-C₃SnO₂ trigonal bipyamidal configuration with the oxygen atoms occupying axial positions. Complex 4 adopts a monomeric structure with two carboxylates coordinated to tin in a monodentate form from axial and equatorial positions, and with the coordination number raised to five as the methanol occupies the apical position of the trigonal bipyramid.     

Synthesis, characterization and catalytic behaviour of ansa-zirconocene complexes containing tetraphenylcyclopentadienyl rings: X-ray crystal structures of [Zr{Me2Si(η-C5Ph4)(η-C5H3R)}Cl2] (R = H, Bu)

The ansa-bis(cyclopentadiene) compounds, Me₂Si(C₅HPh₄)(C₅H₄R) (R = H (2); Bu^t (3)), have been prepared by the reaction of C₅HPh₄(SiMe₂Cl) (1) with Na(C₅H₅) or Li(C₅H₄Bu^t), respectively, and transformed to the di-lithium derivatives, Li₂{Me₂Si(C₅Ph₄)(C₅H₃R)} (R = H (4); Bu^t (5)), by the action of n-butyllithium. The ansa-zirconocene complexes, [Zr{Me₂Si(η⁵-C₅Ph₄)(η⁵-C₅H₃R)}Cl₂] (R = H (6); Bu^t (7)), were synthesized from the reaction of ZrCl₄ with 4 or 5, respectively. Compounds 6 and 7 have been tested in the polymerization of ethylene and compared with their methyl-substituted analogues, [Zr{Me₂Si(η⁵-C₅Me₄)(η⁵-C₅H₃R)}Cl₂] (R = H (8); Bu^t (9)). Whilst 8 and 9 are catalytically active, the tetraphenyl-substituted complexes 6 and 7 proved to be inactive in the polymerization of ethylene. This phenomenon has been explained by DFT calculations based on the reaction intermediates in the polymerization processes involving 6 and 7, which showed that the extraction of a methyl group from the zirconocene complex to form the cationic active specie is endothermic and therefore unfavourable.     

A contribution to 1-azapentadienylmetal chemistry: Si, Sn(II), Fe(II) and Co(II) complexes

Complexes of three related 1-azapentadienyl ligands [N(SiMe₂R¹)C(Bu^t)(CH)₃SiMe₂R]⁻, abbreviated as L (R = Bu^t, R¹ = Me), L′ (R = Me = R¹), and L″ (R = Bu^t = R¹), are described. The crystalline compounds Sn(L)₂ (1), Sn(L′)₂ (2), [Sn(L′)(μ-Cl)]₂ (3) and [Sn(L″)(μ-Cl)]₂ (4) were prepared from SnCl₂ and 2 K(L), 2 K(L′), K(L′) and K(L″), respectively, in thf. Treatment of the appropriate lithium 1-azapentadienyl with Si(Cl)Me₃ yielded the yellow crystalline Me₃Si(L) (5) and the volatile liquid Me₃Si(L′) (6) and Me₃Si(L″) (7), each being an N,N,C-trisilyldieneamine. The red, crystalline Fe(L)₂ (8) and Co(L′)₂ (9) were obtained from thf solutions of FeCl₂ with 2 Li(L)(tmeda) and CoCl₂ with 2 K(L′), respectively. Each of 1-9 gave satisfactory C, H, N analyses; 6 and 7 (GC-MS) and 1, 2, 8 and 9 (MS) showed molecular cations and appropriate fragments (also 3 and 4). The ¹H, ¹³C and ¹¹⁹Sn NMR (1-4) and IR spectra support the assignment of 1-4 as containing Sn-N(SiMe₂R¹)-C(Bu^t)(CH)₃SiMe₂R moieties and 5-7 as N(SiMe₃)(SiMe₂R¹)C(Bu^t)(CH)₃SiMe₂R molecules; for 1-4 this is confirmed by their X-ray structures. The magnetic moments for 8 (5.56 μ_B) and 9 (2.75 μ_B) are remarkably close to the appropriate Fe and Co complex [M{η³-N(SiMe₃)C(Bu^t)C(H)SiMe₃}₂]; hence it is proposed that 8 and 9 have similar metal-centred, centrosymmetric, distorted octahedral structures.     

Preparation and structural studies on diorganotin(IV) complexes of N-nitroso-N-phenylhydroxylaminates

Diorganotin(IV)-complexes of the N-nitroso-N-phenylhydroxylaminates (hereinafter cupf), Et₂Sn(cupf)₂ (1), Bu₂Sn(cupf)₂ (2), {[Bu₂Sn(cupf)]₂O}₂ (3), t-Bu₂Sn(cupf)₂ (4) and Oc₂Sn(cupf)₂ (5, 6) were prepared and characterised by FT-IR and Mössbauer spectroscopic measurements. The binding modes of the ligand were identified by FT-IR spectroscopy, and it was found that the ligand is coordinated in chelating or bridging mode to the organotin(IV) center. The ¹¹⁹Sn Mössbauer and FT-IR studies support the formation of trans-O_h (1-6) structures. The X-ray diffraction analysis of 4 revealed that the tin centre is in a skew-trapezoidal geometry defined by four donors derived from the cupferronato ligands and two carbon atoms from the tin-bound ^tbutyl substituents. The ¹¹⁹Sn NMR investigations indicate that in solution 4 retains its hexacoordinated nature.     

Synthesis of electronically and coordinatively unsaturated complexes [Ru2(CO)4(μ-H)(μ-PBu2)(μ-L2)] (L2 = biphosphanes)

A convenient synthesis and the characterization of six new electronically and coordinatively unsaturated complexes of the formula [Ru₂(CO)₄(μ-H)(μ-P^tBu₂)(μ-L₂)] (2b-g) (RuRu) is described exhibiting a close relation to the known [Ru₂(CO)₄(μ-H)(μ-P^tBu₂)(μ-dppm)] (2a). The complexes 2b-g were obtained in a kind of one-pot synthesis starting from [Ru₃(CO)₁₂] and P^tBu₂H in the first step followed by the reaction with the bidentate bridging ligand in the second step. The method was developed for the following bridging ligands (μ-L₂): dmpm (2b, dmpm = Me₂PCH₂PMe₂), dcypm (2c, dcypm = Cy₂PCH₂PCy₂), dppen (2d, dppen = Ph₂PC(=CH₂)PPh₂), dpppha (2e, dpppha = Ph₂PN(Ph)PPh₂), dpppra (2f, dpppra = Ph₂PN(Pr)PPh₂), and dppbza (2g, dppbza = Ph₂PN(CH₂Ph)PPh₂). The molecular structures of all new complexes 2b−g were determined by X-ray diffraction.     

Syntheses, crystal structures and DFT studies of [Me3EM(CO)5] (E = Sb, Bi; M = Cr, W), cis-[(Me3Sb)2Mo(CO)4], and [Bu3BiFe(CO)4]

Syntheses of [Me₃SbM(CO)₅] [M = Cr (1), W (2)], [Me₃BiM(CO)₅] [M = Cr (3), W (4)], cis-[(Me₃Sb)₂Mo(CO)₄] (5), [^tBu₃BiFe(CO)₄] (6), crystal structures of 1-6 and DFT studies of 1-4 are reported.     

Synthesis and reactivity of asymmetrically substituted ansa-bridged zirconocene complexes: X-ray crystal structures of [Zr{R(H)C(η-C5Me4)(η-C5H4)}Cl2] (R = Bu, Bu) and [Zr{Bu(H)C(η-C5Me4)(η-C5H4)}(CH2Ph)2]

The dialkyl complexes, (R = Prⁱ, R′ = Me (2a), CH₂Ph (3a); R = Buⁿ, R′ = Me (2b), CH₂Ph (3b); R = Bu^t, R′ = Me (2c), CH₂Ph (3c); R = Ph, R′ = Me (2d), CH₂Ph (3d)), have been synthesized by the reaction of the ansa-metallocene dichloride complex, [Zr{R(H)C(η⁵-C₅Me₄)(η⁵-C₅H₄)}Cl₂] (R = Prⁱ (1a), Buⁿ (1b), Bu^t (1c), Ph (1d)), and two molar equivalents of the alkyl Gringard reagent. The insertion reaction of the isocyanide reagent, CNC₆H₃Me₂-2,6, into the zirconium-carbon σ-bond of 2 gave the corresponding η²-iminoacyl derivatives, [Zr{R(H)C(η⁵-C₅Me₄)(η⁵-C₅H₄)}{η²-MeCNC₆H₃Me₂-2,6}Me] (R = Prⁱ (4a), Buⁿ (4b), Bu^t (4c), Ph (4d)). The molecular structures of 1b, 1c and 3b have been determined by single-crystal X-ray diffraction studies.     

New group 14 element(IV) β-diiminates and a Sn(II) analogue

Seven group 14 element(IV) compounds 2-7 have been prepared, derived either (2-5) from the potassium β-diketiminate K(L) [L = {N(Ar)C(Me)}₂CH, Ar = C₆H₃Prⁱ₂-2,6] (1) or the known lithium β-dialdiminate Li(L′)] [L′ = {N(Ar)C(H)}₂CPh, Ar = C₆H₃Prⁱ₂-2,6]. Treatment of 1 with Bu^tC(O)Cl, Me₃SiCl, Ph₃SnCl, or Me₃SnCl afforded {N(Ar)C(Me)}₂C(H)C(O)Bu^t (2), [ArNC(Me)C(H)C(Me)N(Ar)SiMe₃] (3), [HN(Ar)C(Me)C(H)C(CH₂SnPh₃)N(Ar)] (4), or (5), respectively. Compounds 4 and 5 are remarkable as they have arisen from a tautomer of 1; crystalline centrosymmetric 5 has a fused tricyclic structure, a central eight-membered ring flanked by two six-membered rings. The compounds [GeCl₂(L′)(OGeCl₃)] (6) or [SnCl(L′)Me₂] (7), the first group 14 metal β-dialdiminates, were obtained from Li(L′) and (GeCl₃)₂O or Me₂SnCl₂, respectively. The Sn(II) compound SnCl(L′) (8) was prepared from SnCl₂ and K(L′). The molecular structures of the crystalline compounds 3-8 are reported.     

Novel titana-2,4-cyclopentadienes by 1,1-alkylboration

Bis(trimethylsilyl)amino-(2,2,5,5-tetramethyl-1,2,5-azadisila-cyclopent-1-yl)-titanium dichloride (3) and bis(2,2,5,5-tetramethyl-1,2,5-azadisila-cyclopent-1-yl)-titanium dichloride (4) were prepared and converted into the di(1-alkynyl)titanium derivatives, (Me₃Si)₂N[(CH₂Me₂Si)₂N]Ti(CCR)₂ (5) and [(CH₂Me₂Si)₂N]₂Ti(CCR)₂ (6) [R=Me (a), Ph (b), SiMe₃ (c)]. The reaction of 5a and 5b with trialkylboranes such as Et₃B leads almost quantitatively to titana-2,4-cyclopentadienes 7a and 7b, in which a diethylboryl group functions as a substituent in 3-position. In the same manner, 6b reacts with Et₃B or Pr₃B to titana-2,4-cyclopentadienes 8b or 9b, respectively. It is proposed that these reactions proceed by 1,1-alkylboration. Compound 5c also reacts with Et₃B, however, a complex mixture was obtained. All products were characterised by ¹H-, ¹¹B-, ¹³C-, ¹⁵N- and ²⁹Si-NMR spectroscopy.     

Palladium complexes of multidentate pyrazolylmethyl pyridine ligands: Synthesis,structures and phenylacetylene polymerization

The compounds, 2,6-bis(3,5-dimethylpyrazol-1-ylmethyl)pyridine (_MeNˆNˆN) (L1) and 2,6-bis(3,5-ditertbutylpyrazol-1-ylmethyl)pyridine (_tBuNˆNˆN) (L2), react with either [Pd(NCMe)₂Cl₂] or [Pd(COD)ClMe] to form the mononuclear palladium complexes [Pd(_MeNˆNˆN)Cl₂] (1), [Pd(_MeNˆNˆN)ClMe] (2), [Pd(_tBuNˆNˆN)Cl₂] (3) and [Pd(_tBuNˆNˆN)ClMe] (4). Reactions of 1, 2 and 4 with the halide abstractor, NaBAr₄ (Ar = 3,5-(CF₃)₂C₆H₃), led to the formation of stable tridentate cationic species [Pd(_MeNˆNˆN)Cl]⁺(5), [Pd(_MeNˆNˆN)Me]⁺ (6) and [Pd(_tBuNˆNˆN)Cl]⁺ (7) respectively. The analogous carbonyl linker cationic species [Pd{(3,5-Me₂pz-CO)₂-py}Cl]⁺ (9) and [Pd{(3,5-^tBu₂pz-CO)₂-py}Cl]⁺ (10), prepared by halide abstraction of the neutral complexes [Pd{(3,5-Me₂pz-CO)₂-py}Cl₂] and [Pd{(3,5-^tBu₂pz-CO)₂-py}Cl₂] by NaBAr₄, were however less stable with t_1/2 of 14 and 2 days respectively. Attempts to crystallize 1 and 3 from the mother liquor resulted in the isolation of the salts [Pd(_MeNˆNˆN)Cl]₂[Pd₂Cl₆] (11) and [Pd(_tBuNˆNˆN)Cl]₂[Pd₂Cl₆] (12). Although when complexes 1–4 were reacted with modified methylaluminoxane (MMAO) or NaBAr₄, no active catalysts for ethylene oligomerization or polymerization were formed, activation with silver triflate (AgOTf) produced active catalysts that oligomerized and polymerized phenylacetylene to a mixture of cis-transoidal and trans-cisoidal polyphenylacetylene.     

Dibenzothiepins, phthalans and phthalides from 4-heterosubstituted dibenzothiins

The lithiation of 4-heterosubstituted dibenzothiins 1 (phenoxathiin, phenothiazine and thianthrene) with lithium and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB, 7.5% molar) in THF at temperatures ranging from −90 to −78°C gives the corresponding functionalised organolithium intermediate I, which by reaction with different electrophiles [H₂O, D₂O, Bu^tCHO, PhCHO, Ph(CH₂)₂CHO, Me₂CO, Et₂CO, (CH₂)₅CO, (CH₂)₇CO] at the same temperature, followed by hydrolysis, gives the expected functionalised thiols 2. Cyclisation of some thiols 2 under acidic conditions leads to the corresponding seven-membered dibenzo heterocycles 5. In the case of thianthrene 1c, after addition of a carbonyl compound as the first electrophile [MeCHO, Bu^tCHO, Me₂CO, Et₂CO, (CH₂)₅CO], the corresponding intermediate II can be lithiated again and react with a second electrophile. Diols 3 are obtained after hydrolysis when a carbonyl compound [Bu^tCHO, PhCHO, Ph(CH₂)₂CHO, Me₂CO, Et₂CO, (CH₂)₅CO] is used as the second electrophile. Acidic cyclisation of diols 3 gives substituted phthalans 6 in almost quantitative yields. Finally, in the case of using carbon dioxide as the second electrophile, phthalides 4 are obtained after acidic hydrolysis.     

Structure of N,C,N-chelated organotin(IV) fluorides

The set of starting tri-, di- and monoorganotin(IV) halides containing N,C,N-chelating ligand (L^NCN = {1,3-[(CH₃)₂NCH₂]₂C₆H₃}⁻) has been prepared (1-5) and two compounds structurally characterized ([L^NCNPh₂Sn]⁺I₃⁻ (1c), L^NCNSnBr₃ (5)) in the solid state. These compounds were reacted with KF with 18-crown-6, NH₄F or L^CNnBu₂SnF to give derivatives containing fluorine atom(s). Triorganotin(IV) fluorides L^NCNMe₂SnF (2a) and L^NCNnBu₂SnF (3a) revealed monomeric structural arrangement with covalent Sn-F bond both in the coordinating and non-coordinating solvents, except the behaviour of 3a that was ionized in the methanol solution at low temperature. The products of fluorination of L^NCNSnPhCl₂ (4) and 5 were described by NMR in solution as the ionic hypervalent fluorostannates or the oligomeric species reacting with chloroform, methanol or moisture to zwitterionic monomeric stannate L^NCN(H)⁺SnF₄⁻ (5c), which was confirmed by XRD analysis in the solid state.