Synthesis and characterization of nickel(II) complexes bearing 2-(imidazol-2-yl)pyridines or 2-(pyridin-2-yl)phenanthroimidazoles/oxazoles and their polymerization of norbornene

Series of 2-R₁-6-(1-R₂-4,5-diphenyl-1H-imidazol-2-yl)pyridine (R₁ = R₂ = H, L1; R₁ = Me, R₂ = H, L2; R₁ = H, R₂ = Me, L3; R₁ = R₂ = Me, L4), 2-(6-R₁-pyridin-2-yl)-1H-phenanthro[9,10-d]imidazole (R₁ = H, L5; R₁ = Me, L6) and 2-(pyridin-2-yl)phenanthro[9,10-d]oxazole (L7) were synthesized and used to prepare their corresponding dihalonickel complexes (C1-C9). All organic compounds and nickel complexes were characterized by elemental and spectroscopic analyses. Molecular structures of C1, C4, C5 and C8 were confirmed by the single-crystal X-ray diffraction analysis. The single-crystal X-ray analysis revealed complex C1 as a distorted octahedral geometry, complex C4 as a distorted square pyramidal geometry, complex C5 as a distorted trigonal bipyramidal configuration, and complex C8 as a tetrahedral geometry. Upon activation with methylaluminoxane (MAO), the nickel complexes showed good activity towards norbornene polymerization through main additional and minor ring-opening metathesis. The reaction parameters such as norbornene concentration, reaction temperature and different coordinate environments caused by the ligands affected their catalytic performances.     

The first metal complexes bearing ligated 3-iminoisoindolin-1-ones

The reaction between Zn(OAc)₂ · 2H₂O (1) and the 3-iminoisoindolin-1-ones H₂NCNC(O)C₆R¹R²R³R⁴ (R¹-R⁴ = H 2; R¹, R⁴ = H, R², R³ = Cl 3; R¹, R³, R⁴ = H, R² = Me 4) in EtCN at 70 °C for ca. 12 h affords the novel family of complexes [Zn{H₂NCNC(O)C₆R¹R²R³R⁴}₂(OAc)₂] (R¹-R⁴ = H 5; R¹, R⁴ = H, R², R³ = Cl 6; R¹, R³, R⁴ = H, R² = Me 7) in excellent (90% and 93% for 5 and 6, correspondingly) to good (64% for 7) yields. The isolated compounds were characterized by elemental analyses (C, H, N), IR, NMR and ESI⁺-MS. X-ray diffraction data for 2 and 5 indicate that both free (2) and ligated (5) 3-iminoisoindolin-1-ones exist in the zwitterionic form.     

Bis(pyrazolyl) palladium(II), platinum(II) and gold(III) complexes: Syntheses, molecular structures and substitution reactions with l-cysteine

A series of pyrazolyl palladium(II), platinum(II) and gold(III) complexes, [PdCl₂(3,5-R₂bpza)] {R = H (1), R = Me (2), bpza = bis-pyrazolyl acetic acid}, [PtCl₂(3,5-R₂bpza)] {R = H (3a), R = Me (4)}, [AuCl₂(3,5-R₂bpza)]Cl {R = H (5a), R = Me (6a)} and [PdCl₂(3,5-R₂bpzate)] {R = Me (7)} have been synthesised and structurally characterised. Single crystal X-ray crystallography showed that the pyrazolyl ligands exhibit N^N-coordination with the metals. Anticancer activities of six complexes 1-6a were investigated against CHO cells and were found to have low activities. Substitution reactions of selected complexes 1, 2, 3a and 5a with l-cysteine show that the low anticancer activities compounds and that the rate of substitution with sulfur-containing compounds is not the cause of the low anticancer activities.     

Synthesis, spectroscopic properties, X-ray single crystal analysis and antimicrobial activities of organotin(IV) 4-(4-methoxyphenyl)piperazine-1-carbodithioates

A series of mononuclear organotin(IV) complexes of the types, R₃SnL {R = C₄H₉ (1), C₆H₁₁ (2), CH₃ (3) and C₆H₅ (4)}, R₂SnClL {R = C₄H₉ (5), C₂H₅ (7) and CH₃ (9)} and R₂SnL₂ {R = C₄H₉ (6), C₂H₅ (8) and CH₃ (10)}, have been synthesized, where L = 4-(4-methoxyphenyl)piperazine-1-carbodithioate. The ligand-salt and the complexes have been characterized by Raman, FT-IR and multinuclear NMR (¹H, ¹³C and ¹¹⁹Sn) spectroscopy and elemental microanalysis (CHNS). The spectroscopic data substantiate coordination of the ligands to the organotin moieties. The structures of complexes 4 and 6 have been determined by single-crystal X-ray diffraction and illustrate the asymmetric bidentate bonding of the ligand. The packing diagrams indicate O···H and π···H intermolecular interactions in complex 4 and intermolecular S₂C···H interactions in complex 6, resulting in layer structures for both complexes. A subsequent antimicrobial study indicates that the compounds are active biologically and may well be the basis for a new class of fungicides.     

Bimetallic copper(II) and zinc(II) complexes of acyclic Schiff base ligands derived from amino acids

The acyclic Schiff-base ligands (2-(OH)-5-(R³)C₆H₂-1,3-(HCNC(R¹)(R²)CO₂H), derived from the dialdehyde 2-hydroxy-5-R-1,3-benzenedicarboxaldehyde (R = Me or t-Bu) and two equivalents of the amino acids glycine, 2,2-diphenylglycine or phenylalanine, have been reacted with the metal acetates M(OAc)₂ (M = Cu, Zn) in the presence of triethylamine, affording the complexes [HNEt₃][M₂(CH₃CO₂)₂(2-(O)-5-(t-Bu)C₆H₂-1,3-(HCNC(R¹)(R²)CO₂)₂] (M = Cu, R¹ = R² = C₆H₅, R³ = Me (1); M = Zn, R¹ = R² = H, R³ = t-Bu (2); M = Zn, R¹ = R² = C₆H₅, R³ = t-Bu (3); M = Zn, R¹ = H, R² = CH₂C₆H₅, R³ = t-Bu (4)) in good yields. The crystal structures of 1·MeCN, 2·, 3·2MeOH, and 4·3MeOH have been determined.     

Synthesis and structure of dichloropalladium(II) complexes of heteroleptic N,S- and N,Se-donor ligands based on the 2-organochalcogenomethylpyridine motif, and Mizoroki-Heck catalysis mediated by complexes of N,S-donor ligands

Ligands containing the 2-organochalcogenomethylpyridine motif with substituents in the 4- or 6-position of the pyridyl ring, R⁴,R⁶-pyCH₂ER¹ [R⁴ = R⁶ = H, ER¹ = SMe (1), SeMe (2), SPh (6), SePh (7); R⁴ = Me, R⁶ = H, ER¹ = SMe (3), SPh (8), SePh (9); R⁴ = H, R⁶ = Me, ER¹ = SMe (4), SPh (10), SePh (11); R⁴ = H, R⁶ = Ph, ER¹ = SMe (5), SPh (12), SePh (13)] are obtained on the reaction of R⁴,R⁶-pyMe with LiBuⁿ followed by R¹EER¹. On reaction with PdCl₂(NCMe)₂, the ligands with a 6-phenyl substituent form cyclopalladated species PdCl{6-(o-C₆H₄)pyCH₂ER¹-C,N,E} (5a, 12a, 13a) with the structure of 13a (ER¹ = SePh) confirmed by X-ray crystallography; other ligands form complexes of stoichiometry PdCl₂(R⁴,R⁶-pyCH₂ER¹). Complexes with R⁶ = H are monomeric with N,E-bidentate configurations, confirmed by structural analysis for 3a (R⁴ = Me, ER¹ = SMe), 7a (R⁴ = H, ER¹ = SePh) and 9a (R⁴ = Me, ER¹ = SePh). Two of the 6-methyl substituted complexes examined by X-ray crystallography are oligomeric with trans-PdCl₂(N,E) motifs and bridging ligands, trimeric [PdCl₂(μ-6-MepyCH₂SPh-N,S)]₃ (10a) and dimeric [PdCl₂(μ-6-MepyCH₂SePh-N,Se)]₂ (11a). This behaviour is attributed to avoidance of the Me···Cl interaction that would occur in the cis-bidentate configuration if the pyridyl plane had the same orientation with respect to the coordination plane as observed for 3a, 7a and 9a [dihedral angles 8.0(2)-16.8(2)°]. When examined as precatalysts for the Mizoroki-Heck reaction of n-butyl acrylate with aryl halides in N,N-dimethylacetamide at 120 °C, the complexes exhibit the anticipated trends in yield (ArI > ArBr > ArCl, higher yield for electron withdrawing substituents in 4-RC₆H₄Br and 4-RC₆H₄Cl). The most active precatalysts are PdCl₂(R⁴-pyCH₂SMe-N,S) (R = H (1a), Me (3a)); complexes of the selenium containing ligands exhibit very low activity. For closely related ligands, the changes SMe to SPh, 6-H to 6-Me, and 6-H to 6-Ph lead to lower activity, consistent with involvement of both the pyridyl and chalcogen donors in reactions involving aryl bromides. The precatalyst PdCl₂(pyCH₂SMe-N,S) (1a) exhibits higher activity for the reaction of aryl chlorides in Buⁿ₄NCl at 120 °C as a solvent under non-aqueous ionic liquid (NAIL) conditions.     

Phosphane- and phosphite-silver(I) phenolates: Synthesis, characterization and their use as CVD precursors

The silver(I) salts [AgOR] (3a, R = C₉H₆N; 3b, R = C₆H₄-2-CHO, 3c, R = C₆H₄-2-Cl; 3d, R = C₆H₄-2-CN; 3e, R = C₆H₄-2-NO₂) are accessible by the stoichiometric reaction of [AgNO₃] (1) with HOR (2a, R = C₉H₆N; 2b, R = C₆H₄-2-CHO; 2c, R = C₆H₄-2-Cl; 2d, R = C₆H₄-2-CN; 2e, R = C₆H₄-2-NO₂) in presence of NEt₃. Treatment of 3a-3e with PⁿBu₃ (4), P(OMe)₃ (5a) or P(OCH₂CF₃)₃ (5b) in the ratios of 1:1 and 1:2, respectively, produced complexes [L_mAgOR] (L = PⁿBu₃, m = 1: 6a, R = C₉H₆N; 6b, R = C₆H₄-2-CHO; 6c, R = C₆H₄-2-Cl; 6d, R = C₆H₄-2-CN; 6e, R = C₆H₄-2-NO₂. m = 2: 7a, R = C₉H₄; 7b, R = C₆H₄-2-CHO; 7c, R = C₆H₄-2-Cl; 7d, R = C₆H₄-2-CN; 7e, R = C₆H₄-2-NO₂. L = P(OMe)₃, m = 1: 8a, R = C₆H₄-2-CHO; 8b, R = C₆H₄-2-NO₂. m = 2: 9, R = C₆H₄-2-NO₂. L = P(OCH₂CF₃)₃, m = 1: 10, R = C₆H₄-2-NO₂). Based on TGA, temperature-programmed and in situ molecular beam mass spectrometry metal-organic 7e was applied as CVD precursor in the deposition of silver onto glass substrates. The resulting silver films were characterized by XRD. The SEM image of a film grown from 7e at 350 °C showed a homogeneous surface with grain sizes of 40 nm. The molecular structures of 8b and 10 in the solid state were determined. They are isostructural and are cubane-like structured. Low-temperature ³¹P{¹H} NMR studies showed that the title complexes are dynamic in solution and exchange at room temperature their ligands.     

Silver(I) acetylides stabilized by η-alkynes: Synthesis, reaction chemistry and solid state structures

Individual synthetic routes to heterobimetallic Ti(IV)-Ag(I) acetylides of type {[Ti](μ-σ,π-CCR¹)₂}AgCCR² ([Ti] = (η⁵-C₅H₄SiMe₃)₂Ti: R¹ = SiMe₃: 6, R² = SiMe₃; 7, R² = Ph. R¹ = ^tBu: 8, R² = SiMe₃; 9, R² = Ph. [Ti] = (η⁵-C₅H₅)₂Ti): 10, R¹ = ^tBu, R² = SiMe₃) including (i) the reaction of {[Ti](μ-σ, π-CCR¹)₂}AgNO₃ ([Ti] = (η⁵-C₅H₄SiMe₃)₂Ti): 1, R¹ = SiMe₃; 2, R¹ = ^tBu. [Ti] = (η⁵-C₅H₅)₂Ti: 3, R¹ = ^tBu) with LiCCR² (4, R² = SiMe₃; 5, R² = Ph) and (ii) treatment of [Ti](CCSiMe₃)₂ ([Ti] = (η⁵-C₅H₄SiMe₃)₂Ti) (11) with [AgCCR²] (12, R² = SiMe₃; 13, R² = Ph) are described. The reactions of 1-3 with 4 or 5 appeared to be sensitive towards stoichiometry because an excess of 4 or 5 resulted in the formation of [(Ag(CCR²)₂)Li(OEt₂)]_n (14) and [Ti](CCR¹)₂. Coordination polymer 14 is also accessible, when, for example, [AgCCSiMe₃] (12) is treated with 1 eq. of LiCCSiMe₃ (4) in diethyl ether.The titanium(IV)-silver(I) acetylides 6-10 are stable in the dark and at low temperature, while on exposure to light and on heating they decompose to give R²CC-CCR² together with [Ti](CCR¹)₂ and elemental silver.Complexes 6-10 contain a mono-nuclear AgCCR² entity stabilized by the chelate-bonded organometallic π-tweezer molecule [Ti](CCSiMe₃)₂, which was evinced by structure determination of 7 in the solid state. In 14 linear [Me₃SiCC-Ag-CCSiMe₃]⁻ units are connected by [Li(OEt₂)]⁺ building blocks forming a coordination polymer.     

Lewis-base copper(I) formates: Synthesis, reaction chemistry, structural characterization and their use as spin-coating precursors for copper deposition

Consecutive synthesis methodologies for the preparation of a series of copper(I) formates [L_mCuO₂CH] (L = ⁿBu₃P: 4a, m = 1; 4b, m = 2; 5, L = [Ti](CCSiMe₃)₂, m = 1, [Ti] = (η⁵-C₅H₄SiMe₃)₂Ti) and [L_mCuO₂CH·HO₂CR] (L = ⁿBu₃P: 7a, m = 1, R = H; 7b, m = 2, R = H; 7c, m = 2, R = Me; 7d, m = 2, R = CF₃; 7e, m = 2, R = Ph. L = (^cC₆H₁₁)₃P, R = H: 8a, m = 2; 8b, m = 3. L = (CF₃CH₂O)₃P, R = H: 9a, m = 2; 9b, m = 3. L = (CH₃CH₂O)₃P, R = H: 10a, m = 2; 10b, m = 3. L = [Ti](CCSiMe₃)₂; m = 1: 11a, R = H; 11b, R = Ph) is reported using [CuO₂CH] (1) and L (2a, L = ⁿBu₃P; 2b, L (^cC₆H₁₁)₃P; 2c, L = (CF₃CH₂O)₃P; 2d, L = (CH₃CH₂O)₃P; 3, L = [Ti](CCSiMe₃)₂) as key starting materials. Addition of formic acid (6a) or carboxylic acid HO₂CR (6b, R = Me; 6c, R = CF₃; 6d, R = Ph) to the afore itemized copper(I) formates 4 and 5 gave metal-organic or organometallic 7-11. The molecular structures of 8a and 11a in the solid state are reported showing a threefold coordinated copper(I) ion, setup by either two coordinatively-bonded phosphorus atoms and one formate oxygen atom (8a) or two π-bonded alkyne ligands and one oxygen atom (11a). A formic acid molecule is additionally hydrogen-bonded to the CuO₂CH moiety. The use of 7b as suitable precursor for the deposition of copper onto TiN-coated oxidized silicon wafers by the spin-coating process below 300 °C is described. Complex 7b offers an appropriate transformation behavior into metal phase by an elimination-decarboxylation mechanism. The morphology of the copper films strongly depends on the annealing conditions. A closed grain network densified by a post-treatment is obtained (8 °C min⁻¹, N₂/H₂ carrier gas). Hydrogen post-anneal to 420 °C after film deposition gave a copper film showing resistivities from 2.5 to 3.7 μΩ cm. This precursor was also used for gap-filling processes.     

Palladium(II), platinum(II), ruthenium(II) and mercury(II) complexes of potentially tridentate Schiff base ligands of (E, N, O) type (E = S, Se, Te): Synthesis, crystal structures and applications in Heck and Suzuki coupling reactions

Schiff bases of 2-hydroxybenzophenone (HBP) (C₆H₅)(2-HOC₆H₄)CN(CH₂)_nEAr (L1/L2: E = S, Ar = Ph, n = 2/3; L3/L4: E = Se, Ar = Ph, n = 2/3; L5/L6: E = Te, Ar = 4-MeOC₆H₄, n = 2/3) and their complexes [PdCl(L-H)] (L = L1−L6; 1, 2, 3, 5, 7, 11), [PtCl(L3-H/L5-H)] (4/8), [PtCl₂(L4/L6)₂] (6/12), [(p-cymene)RuCl(L5/L6)]Cl (9/13) and [HgBr₂(L5/L6)₂] (10/14) have been synthesized and characterized by proton, carbon-13, selenium-77 and tellurium-125 NMR, IR and mass spectra. Single crystal structures of L1, 1, 3, 4, 5 and 7 were solved. The Pd-E bond distances (Å): 2.2563(6) (E = S), 2.3575(6)−2.392(2) (E = Se); 2.5117(5)−2.5198(5) (E = Te) are near the lower end of the bond length range known for them. The Pt-Se bond length, 2.3470(8) Å, is also closer to the short values reported so far. The Heck and Suzuki reaction were carried out using complexes 1, 3, 5 and 7 as catalysts under aerobic condition. The percentage yields for trans product in Heck reaction were found upto 85%.     

Synthesis, characterisation and solution behaviour of fluoroalkyl phosphoryl complexes of tin tetrachloride

The synthesis, characterisation and solution behaviour of a series of octahedral complexes SnCl₄·2L (L = R₂NP(O)(OCH₂CF₃)₂; R = Me (1); Et (2) or L = P(O)(OCH₂R_f)₃; R_f = CF₃ (3); C₂F₅ (4)) are described. Complexes 1-4 were prepared from SnCl₄ and 2 equiv. of the ligand, L, in anhydrous CH₂Cl₂ solution. The adducts have been characterised by multinuclear (¹H, ³¹P and ¹¹⁹Sn) NMR, IR spectroscopy and elemental analysis. In dichloromethane solution, the NMR data showed the presence of a mixture of cis and trans isomers for 1 and 2 and only the cis isomer for 3 and 4. The difference could be interpreted in terms of the electronic effects of the substituents on the phosphorus atom of the ligand. In addition, the solution structure of the complexes studied by variable temperature ³¹P-{¹H} and ¹H NMR in the presence of excess ligand indicated that the ligand exchange on the cis isomer dominates the chemistry. The metal-ligand exchange barriers were estimated to be 13.38 and 11.39 kcal/mol for 1 and 3, respectively. The results are discussed and compared with those previously reported for the related hexamethylphosphoramide adduct, SnCl₄·2HMPA.     

Synthesis of fluorous sulfur/carbon/sulfur pincer ligands and palladium complexes: New catalyst precursors for the Heck reaction

Reactions of 1,3-C₆H₄(CH₂Br)₂ and the thiols HSCH₂CH₂R_fn (R_fn = (CF₂)_n−1CF₃; n = 8, 10), or the dithiol 1,3-C₆H₄(CH₂SH)₂ and ICH₂CH₂R_fn, in the presence of carbonate or NaOEt (70-78 °C) give the title ligands 1,3-C₆H₄(CH₂SCH₂CH₂R_fn)₂ (4-R_f8, 58-61%; 4-R_f10, 49-50%). Reactions of 4-R_fn and Pd(OC(O)CF₃)₂ or (PhCN)₂Pd(Cl)₂ (80 °C) afford the title complexes (n/X = 8/OC(O)CF₃ (5-R_f8), 44%; 10/OC(O)CF₃, 58%; 8/Cl (6-R_f8), 45%; 10/Cl, 79%). Both 5-R_f8 and 6-R_f8 are effective catalyst precursors for the Heck reaction of iodobenzene and methyl acrylate (0.21-0.23 mol%, DMF, i-Pr₂NEt, 100-125 °C). However, no active catalyst can be recycled by a subsequent extraction with fluorous solvents. Rather, activity remains in the reddish DMF phase, and is quenched by the addition of mercury. Palladium nanoparticles are visible by transmission electron microscopy. These, or low valent species derived therefrom, are believed to be the active catalysts, in accord with other recent studies involving related non-fluorous and fluorous palladacycles. The CF₃C₆F₁₁/toluene partition coefficients of representative compounds are determined.     

Platinum(II) and palladium(II) complexes with (N,N') and (C,N,N')- ligands derived from pyrazole as anticancer and antimalarial agents: synthesis, characterization and in vitro activities

The study of the reactivity of three 1-(2-dimethylaminoethyl)-1H-pyrazole derivatives of general formula [1-(CH₂)₂NMe₂}-3,5-R₂-pzol] {where pzol represents pyrazole and RH (1a), Me (1b) or Ph (1c)} with [MCl₂(DMSO)₂] (MPt or Pd) under different experimental conditions allowed us to isolate and characterize cis-[M{κ²-N,N′-{[1-(CH₂)₂NMe₂}-3,5-R₂-pzol])}Cl₂] {MMPtPt (2a-2c) or Pd (3a-3c)} and two cyclometallated complexes [M{κ³-C,N,N′-{[1-(CH₂)₂NMe₂}-3-(C₅H₄)-5-Ph-pzol])}Cl] {MPt(II) (4c) or Pd(II) (5c)}. Compounds 4c and 5c arise from the orthometallation of the 3-phenyl ring of ligand 1c. Complex 2a has been further characterized by X-ray crystallography. Ligands and complexes were evaluated for their in vitro antimalarial against Plasmodium falciparum and cytotoxic activities against lung (A549) and breast (MDA MB231 and MCF7) cancer cellular lines. Complexes 2a-2c and 5c exhibited only moderate antimalarial activities against two P. falciparum strains (3D7 and W2). Interestingly, cytotoxicity assays revealed that the platinacycle 4c exhibits a higher toxicity than cisplatin in the three human cell lines and that the complex 2a presents a remarkable cytotoxicity and selectivity in lung (IC₅₀ = 3 μM) versus breast cancer cell lines (IC₅₀ > 20 μM). Thus, complexes 2c and 4c appear to be promising leads, creating a novel family of anticancer agents. Electrophoretic DNA migration studies in presence of the synthesized compounds have been performed, in order to get further insights into their mechanism of action.     

Diiron and diruthenium aminocarbyne complexes containing pseudohalides: stereochemistry and reactivity

Acetonitrile is easily displaced from [Fe₂{μ-CN(Me)(R)}(μ-CO)(CO)(MeCN)(Cp)₂][SO₃CF₃] (R = 2,6-Me₂C₆H₃ (Xyl) (1a); Me (1b)) upon stirring in THF at room temperature in the presence of [NBu₄][SCN]. The resulting complexes trans-[Fe₂{μ-CN(Me)(R)}(μ-CO)(CO)(NCS)(Cp)₂] (R = Xyl (trans-2a); Me (trans-2b)) are completely isomerised to cis-[Fe₂{μ-CN(Me)(R)}(μ-CO)(CO)(NCS)(Cp)₂] (R = Xyl (cis-2a); Me (cis-2b)) when heated at reflux temperature. Similarly, the complexes cis-[M₂{μ-CN(Me)(R)}(μ-CO)(CO)(NCO)(Cp)₂] (M = Fe, R = Me (4a); M = Ru, R = Xyl (4b); M = Ru, R = Me (4c)) and cis-[M₂{μ-CN(Me)(R)}(μ-CO)(CO)(N₃)(Cp)₂] (M = Fe, R = Xyl (5a); M = Fe, R = Me (5b); M = Ru, R = Xyl (5c)) can be obtained by heating at reflux temperature a THF solution of [M₂{μ-CN(Me)(R)}(μ-CO)(CO)(MeCN)(Cp)₂][SO₃CF₃] (M = Fe, R = Xyl (1a); M = Fe, Me (1b); M = Ru, R = Xyl (1c); M = Ru, R = Me (1d)) in the presence of NaNCO and NaN₃, respectively. The reactions of 5 with MeO₂CCCCO₂Me, HCCCO₂Me and (NC)(H)CC(H)(CN) afford the triazolato complexes [M₂{μ-CN(Me)(R)}(μ-CO)(CO){N₃C₂(CO₂Me)₂}(Cp)₂] (M = Fe, R = Xyl (6a); M = Fe, R = Me (6b); M = Ru, R = Xyl (6c)), [M₂{μ-CN(Me)(R)}(μ- CO)(CO){N₃C₂(H)(CO₂Me)}(Cp)₂] (M = Fe, R = Me (7a); M = Ru, R = Xyl (7b)) and [Fe₂{μ-CN(Me)(Xyl)}(μ-CO)(CO){N₃C₂(H)(CN)}(Cp)₂] (8), respectively. The asymmetrically substituted triazolato complexes 7-8 are obtained as mixtures of N(1) and N(2) bonded isomers, whereas 6 exists only in the N(2) form. Methylation of 6-8 results in the formation of the triazole complexes [Fe₂{μ-CN(Me)(Xyl)}(μ-CO)(CO){N₃(Me)C₂(CO₂Me)₂}(Cp)₂][CF₃SO₃] (9), [M₂{μ-CN(Me)(R)}(μ-CO)(CO){N₃(Me)C₂(H)(CO₂Me)}(Cp)₂][CF₃SO₃] (M = Fe, R = Me (10a); M = Ru, R = Xyl (10b)) and [Fe₂{μ-CN(Me)(Xyl)}(μ-CO)(CO){N₃(Me)C₂(H)(CN)}(Cp)₂][CF₃SO₃], 11. The crystal structures of trans-2b, 4b · CH₂Cl₂, 5a, 6b · 0.5CH₂Cl₂ and 8 · CH₂Cl₂ have been determined.     

Synthesis, structures and luminescent behaviour of tridentate salicylaldiminato-type borate complexes

Treatment of the ligands 3,5-tBu₂-2-(OH)C₆H₂CHNR [R = 2-(CO₂H)C₆H₄ (1a) and 2-(CO₂H)C₁₀H₆ (1b)] with trimethylborate, B(OMe)₃, in toluene yields, after work-up, the yellow crystalline complexes {[3,5-tBu₂-2-(O)C₆H₂CHNR]B(OMe)} [R = 2-(CO₂)C₆H₄ (2a) and 2-(CO₂)C₁₀H₆ (2b)], respectively. Further treatment of these complexes with trifluoromethanesulfonic (triflic) acid, CF₃SO₃H, followed by recrystallisation from tetrahydrofuran (thf) afforded the triflate salts [{3,5-tBu₂-2-(O)C₆H₂CHNR}B(thf)][CF₃SO₃] [R = 2-(CO₂)C₆H₄ (3a) and 2-(CO₂)C₁₀H₆ (3b)]. An electroluminescent device was constructed using 2a, which produced orange-green light with broad emission spectra (maximum brightness of 5 cd/m² being observed at 13 V). Compounds 1a and 2b·2MeCN have been characterised by single crystal X-ray structure determinations.     

Syntheses and characterization of triorganotin(IV) complexes of Schiff base derive from 4-amino-5-phenyl-4H-1,2,4-triazole-3-thiol and 5-amino-1,3,4-thiadiazole-2-thiol with p-phthalaldehyde

Eight triorganotin complexes of the types [(R₃Sn)₂(C₂₄H₁₆N₈S₂)].Y (R = Ph, Y = 0 (1); R = PhCH_2, Y = 2CH₃OH (2); R = n-Bu, Y = 0 (3)), [(R₃Sn)₂(C₂₄H₁₆N₈S₂)]_n (R = Me (4)), [(R₃Sn)₂(C₁₂H₆N₆S₄)] · Y (R = Ph, Y = CH₂Cl₂ (5); R = PhCH_2, Y = 0 (6)) and [(R₃Sn)₂(C₁₂H₆N₆S₄)] (R = Bu (7), R = Me (8)) have been obtained by H₂L₁ (H₂L₁ derived from 4-amino-5-phenyl-4H-1,2,4-triazole-3-thiol) and H₂L₂ (H₂L₂ derived from 5-amino-1,3,4-thiadiazole-2-thiol) with triorganotin chloride in the presence of sodium ethoxide. All the complexes were characterized by elemental, IR and NMR spectra analyses, except for complexes 1, 3, 6 and 8, other complexes were also characterized by X-ray diffraction analyses, which reveal that complexes 2 and 5 are dinuclear structures, complex 4 has a 2D network structure and complex 7 forms a macrocyclic structure linked by intermolecular N → Sn interactions.     

Investigation on the coordination modes: Syntheses, characterization and crystal structures of diorganotin (IV) dichloride with 4(5)-imidazoledithiocarboxylic acid

A series of diorganotin (IV) complexes of the types of R₂SnCl(SSCC₃H₃N₂) (R = CH₃1, ⁿBu 2, C₆H₅3 and C₆H₅CH₂4), R₂Sn(SSCC₃H₃N₂)₂ (R = CH₃5, ⁿBu 6, C₆H₅7 and C₆H₅CH₂8) and R₂Sn(SSCC₃H₂N₂) (R = CH₃9, ⁿBu 10, C₆H₅11 and C₆H₅CH₂12) have been obtained by reactions of 4(5)-imidazoledithiocarboxylic acid with diorganotin (IV) dichlorides in the presence of sodium ethoxide. All complexes are characterized by elemental, IR, ¹H, ¹³C and ¹¹⁹Sn NMR spectra analyses. Also, the complexes 1, 7 and 9 are characterized by X-ray crystallography diffraction analyses, which reveal that the complex 1 is monomeric structure with five-coordinate tin (IV) atom, the complex 7 is monomeric structure with six-coordinate tin (IV) atom and the complex 9 is one-dimensional chain with five-coordinate tin (IV) atom.     

An efficient route to substituted 1-silacyclopent-2-enes and 1-silacyclohex-2-enes via consecutive 1,2-hydroboration and 1,1-organoboration

The reaction of alkyn-1-yl(vinyl)silanes R₂Si(CCR¹)CHCH₂ [R = Me (1), Ph (2); R¹ = ^tBu (a), Ph (b), SiMe₃ (c)] with 9-borabicyclo[3.3.1]nonane in a 1:1 ratio affords the 1-silacyclopent-2-ene derivatives 4a-c (R = Me) and 5a-c (R = Ph) as a result of selective intermolecular 1,2-hydroboration of the vinyl group, followed by intramolecular 1,1-organoboration of the alkynyl substituent. The analogous reaction sequence converts the alkyn-1-yl(allyl)dimethylsilanes 3a,c into the 1-silacyclohex-2-ene derivatives 7a,c. All reactions were monitored by ²⁹Si NMR spectroscopy and the structural assignment of the final products was based on multinuclear magnetic resonance data (¹H, ¹¹B, ¹³C and ²⁹Si NMR). The molecular structure of 6a was determined by X-ray analysis.     

Cyclometalated rhodium(III) and iridium(III) complexes containing amino acids as N,O-chelates

The synthesis of bis-cyclometalated aminocarboxylato complexes [M(α-aminocarboxylato)(ptpy)₂] (M = Rh, 3, 4, 5; M = Ir, 6, 7, 8), ptpy = 2-(p-tolyl)pyridinato; aminocarboxylato = glycinato, l-alaninato, l-prolinato) from [{M(μ-Cl)(ptpy)₂}₂] (M = Rh, 1; M = Ir, 2) is described. The molecular structure of [Ir(l-alaninato)(ptpy)₂] (7) was confirmed by a single-crystal X-ray diffraction study. Compound 7 crystallized from methanol-iso-hexane in the space group P2₁. For 7 the two diastereoisomers Δ_Ir, S_C and Λ_Ir, S_C were found crystallizing twice per unit. Absorption and emission spectra were recorded. The rhodium compounds are weak yellow-green and the iridium species strong green emitters.     

Synthesis and structure of Sb←O intramolecularly coordinated ethynylstibanes

The reaction of OCO chelated organolithium compound LLi (1) (L = 2,6-(t-BuOCH₂)₂C₆H₃) with SbCl₃ in 2:1 molar ratio gave diorganoantimony compound L₂SbCl (2). The reactions of the compound 2 with selected lithium acetylides resulted to the Sb←O coordinated antimony acetylides L₂Sb(CCR) (R = Ph, (3), t-Bu (4), Me₃Si (5)). All studied compounds were characterized by the help of elemental analysis, ¹H and ¹³C NMR spectroscopy and IR spectroscopy. Molecular structures of the compounds 2-4 were determined using the X-ray diffraction technique in the solid state.