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.     

Novel bis(β-diketonato)diorganotin(IV) derivatives containing bulky 4-acyl-5-pyrazolonato ligands: Influence of the steric hindrance of the acyl moiety on the solid state structures of tin complexes and their behaviour in solution

New (Q)₂SnR₂ derivatives (HQ in general; in detail: HQ^CHPh₂ = 4-diphenylacetyl-3-methyl-1-phenyl-5-pyrazolone; HQ^Bn = 3-methyl-1-phenyl-4-phenylacetyl-5-pyrazolone; HQ^naph = 3-methyl-4-naphthoyl-1-phenyl-5-pyrazolone; R = CH₃, C₂H₅, C₆H₁₁, n- and t-C₄H₉, C₆H₅,) have been synthesised and characterised by analytical and spectral techniques. Variable temperature NMR studies of (Q^CHPh₂)₂SnR₂ derivatives (R = CH₃ and C₂H₅) in chlorohydrocarbon solvents indicate a fluxional behaviour, with rapid interconversion between six- and five-coordinate species, the latter containing a bidentate acylpyrazolonate and a monodentate one. The X-ray crystal structures of the diorganotin(IV) derivatives (Q^CHPh₂)₂SnMe₂, (Q^CHPh₂)₂SnEt₂, (Q^Bn)₂SnMe₂ and , inclusive of a representative of each Q^x family, show the metal centres in a skewed trans octahedral configuration. The 4-acyl moiety of the β-diketonate donor exerts a steric effect which is correlated to structural behaviour in the solid and solution state. A solid state ¹¹⁹Sn CPMAS NMR study of the (Q^Bn)₂SnR₂ (R = CH₃, C₂H₅, t-C₄H₉ and C₆H₅) complexes shows a marked deshielding effect and upfield movement of the ¹¹⁹Sn isotropic chemical shift (δ_iso) through this series. The ¹¹⁹Sn chemical shift spans (Ω) are the largest reported for directly oxo-coordinated Sn(IV) systems, although the markedly reduced Ω value for the (Q^Bn)₂SnPh₂ complex may be indicative of a cis octahedral coordination, in contrast to the trans octahedral coordination characterising the other complexes of this suite.     

Synthesis, characterization and structure of some arylantimony ferrocenylacrylates

A series of arylantimony ferrocenylacrylates with the formula (C₅H₅FeC₅H₄CHCHCO₂)_nSbAr_(5−n) (n=1, 2; Ar C₆H₅, 4-CH₃C₆H₄, 3-CH₃C₆H₄, 2-CH₃C₆H₄, 4-FC₆H₄) have been synthesized and characterized by elemental analysis, IR, ¹H NMR and mass spectra. The crystal structures of C₅H₅FeC₅H₄CHCHCO₂Sb(C₆H₅)₄ (I₁) and (C₅H₅FeC₅H₄CHCHCO₂)₂Sb(C₆H₅)₃ (II₁) have been determined by X-ray diffraction.     

Organic derivatives of aluminium. Part I. Reactions of alkanolamines with aluminium isopropoxide

Reactions of alkanolamines [R₁R₂NXOH; R₁ = H, CH₃, C₂H₅; R₂ = H, CH₃, C₂H₅ and X = -CH₂CH₂-, -CH₂CH₂CH₂-, -CH₂CHCH₃, -C₆H₄CH₂CH₂-] with aluminium isopropoxide in different molar ratios (1 to 3) yield compounds of the type Al(OPrⁱ)_3?n(OXNR₁R₂)_n, where ‘n’ can be 1, 2 and 3. Most of the derivatives are distillable liquids, soluble in common organic solvents and susceptible to hydrolysis even by atmospheric moisture. The new derivatives are characterized by elemental analysis, IR and ¹H NMR spectra. Molecular weight measurements of Al(OPrⁱ)_3?n(OXNR₁R₂)_n reveal them to be tetrameric in nature.     

Synthesis and spectroscopic and X-ray structural characterisation of some para-substituted triaryltin(pentacarbonyl)manganese(I) complexes

A series of para-substituted triaryltin(pentacarbonyl)manganese(I) compounds [(p-XC₆H₄)₃SnMn(CO)₅: II, X=CH₃; III, X=CH₃O; IV, X=CH₃S; V, X=F; VI, X=Cl; VII, X=CH₃S(O₂)] is reported for comparison with the known phenyl analogue I. IR data [ν(CO)] as well as complete ¹¹⁹Sn/⁵⁵Mn/¹³C solution NMR results are given for I-VII. Chemical shifts, ¹¹⁹Sn versus ⁵⁵Mn, except I, correlate well, but have differing single parameter (SP) correlations, ¹¹⁹Sn versus σ_I and ⁵⁵Mn versus σ°_p. These results are compared with previous SP studies of the ¹¹⁹Sn solution NMR spectra of the series, (p-XC₆H₄)₄Sn and (p-XC₆H₄)₃SnY (Y=Cl, Br, I). Full crystal structures are reported for compounds II-VI. All are similar to that of I, with the Mn(CO)₅ moiety being a distorted tetragonal pyramid, and having a quasi-mirror plane through the central C₄MnSnC₃ skeleton. The Ar₃Sn are distorted trigonal propellers with ring torsion angles in the range 30-80°, the exception being IV with one torsion angle of 22°.     

Diazo complexes of osmium: preparation of binuclear derivatives with bis(aryldiazene) and bis(aryldiazenido) bridging ligands

Depending on experimental conditions and the nature of the phosphite, the reaction of OsH₂P₄ [P=P(OEt)₃ and PPh(OEt)₂] with bis(aryldiazonium) salts [N₂Ar-ArN₂](BF₄)₂ [Ar-Ar=4,4^′-C₆H₄-C₆H₄, 4,4^′-(2-CH₃)C₆H₃-C₆H₃(2-CH₃), 4,4^′-C₆H₄-CH₂-C₆H₄ and 1,5-C₁₀H₆] afford the cis and the trans binuclear [{OsHP₄}₂(μ-HNNAr-ArNNH)](BPh₄)₂1, 2 aryldiazene derivatives. These complexes 1, 2 further react with the mono(diazonium) (4-CH₃C₆H₄N₂)BF₄ salt to give the bis(aryldiazene) [{Os(4-CH₃C₆H₄NNH)P₄}₂(μ-HNNAr-ArNNH)](BPh₄)₄3, 4 derivatives. Binuclear bis(aryldiazenido) [{OsP₄}₂(μ-N₂Ar-ArN₂)](BPh₄)₂ (6) [P=P(OEt)₃; Ar-Ar=4,4^′-C₆H₄-C₆H₄, 4,4^′-C₆H₄-CH₂-C₆H₄] complexes were prepared by deprotonating with NEt₃ the nitrile-diazene [{Os(4-CH₃C₆H₄CN)P₄}₂(μ-HNNAr-ArNNH)](BPh₄)₄ (5) derivatives. The aryldiazenido compounds 6 react with HCl to give the new aryldiazene [{OsClP₄}₂(μ-HNNAr-ArNNH)](BPh₄)₂ (7) derivatives. The characterisation of the complexes by IR and ¹H, ³¹P, ¹⁵N NMR data is also discussed. The reaction of the hydride OsH₂(PPh₂OEt)₄ with mono(diazonium) salts was also studied and led exclusively to the mono(aryldiazene) [OsH(ArN NH)(PPh₂OEt)₄]BPh₄ (8) (Ar=C₆H₅, 4-CH₃C₆H₄) derivatives. Spectroscopic data (¹H, ³¹P, ¹⁵N NMR) on ¹⁵N-labelled derivatives suggest the presence of two isomers with the N-bonded and the π-bonded ArNNH ligand, respectively.     

Synthesis, characterizations, and crystal structures of triorganotin(IV) derivatives with areneseleninic acids

Six new triorganotin(IV) complexes, [R₃Sn(O₂SeC₆H₄Cl)]_n (R = Me 1; Ph 2), [R₃Sn(O₂SeC₆H₄Me)]_n (R = Me 3; Ph 4), [R₃Sn(O₂SeC₆H₄Bu)]_n (R = Me 5; Ph 6) have been synthesized by the reaction of 4-chlorobenzeneseleninic acid, p-Tolueneseleninic acid, and 4-tert-butylbenzeneseleninic acid with triorganotin(IV) chloride in the presence of sodium ethoxide. All of the complexes were characterized by elemental analysis, FT-IR, NMR (¹H, ¹³C, and ¹¹⁹Sn) spectroscopy, and X-ray crystallography. Crystal structures show that all of the complexes exhibit 1D infinite chain structures which are generated by the bidentate oxygen atoms and the five-coordinated tin centers.     

Syntheses and characterization of diorganotin(IV) derivatives with areneseleninic acid: X-ray crystal structures of 1D infinite chains containing eight-membered ring

Three new diorganotin(IV) complexes, [Bu₂Sn(O₂SeC₆H₅)₂]_n (1), [Bu₂Sn(O₂SeC₆H₄Me)₂]_n (2), [Me₂Sn(O₂SeC₆H₄Bu)₂]_n (3) have been synthesized by the reaction of benzeneseleninic acid, p-tolueneseleninic acid, and 4-tert-butylbenzeneseleninic acid with Me₂SnCl₂ or Bu₂SnCl₂ in the presence of sodium ethoxide in methanol at 50 °C. All of the complexes were characterized by elemental analysis, FT-IR, NMR (¹H, ¹³C and ¹¹⁹Sn) spectroscopy and X-ray crystallography. X-ray diffraction studies of 1, 2, 3 show that the areneseleninate groups behave as double bridges between the tin atoms leading to polymeric chain structure with Sn₂O₄Se₂ eight-membered ring. The organic groups bonded to the tin atoms are in trans-position in the resulting octahedral arrangement.     

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.     

Self-assembled diorganotin(IV) moieties with 2,3,4,5-tetrafluorobenzoic acid: Syntheses, characterizations and crystal structures

A series of new organotin(IV) derivatives with 2,3,4,5-tetrafluorobenzoic acid: {[(2,3,4,5-F₄C₆HCO₂)R₂Sn]₂O}₂ (R = Et 1, n-Bu 2, Ph 3), [R₂Sn(O₂CC₆F₄H)₂]_n (R = n-Bu 4, Et 5, Ph 6), and Sn₂R₄(O₂CC₆F₄H)₃(OH) (R = Et 7, n-Bu 8, Ph 9), were synthesized by the reaction of diorganotin oxide and 2,3,4,5-tetrafluorobenzoic acid. All the complexes 1-9 have been characterized by elemental analysis, IR, ¹H, ¹³C, ¹¹⁹Sn NMR spectra. Among them complexes 2, 4, 8 were also characterized by X-ray crystallography diffraction analyses. The crystal structure of complex 2 exhibited a tetra-nuclear geometry with the Sn₂O₂ symmetry core. Complex 4 formed a 1D helical double-chain structure through intermolecular O→Sn coordinating and completed a DNA-like assembly. Complex 8 revealed that the both Sn atoms were held together by hydroxide and acetate bridges, forming a chair-like six-membered ring. Moreover, the supramolecular structures of dimer, 1D chain or 2D network have been found in complexes 4 and 8 by intermolecular C-H?F weak hydrogen bond and non-bonded F?F or F?Sn interaction, which were highly effective in the assembly of supramolecular structures and could lead to the formation of complexes with fascinating topologies properties.     

Syntheses, characterization and crystal structure of diorganotin and triorganotin heterocyclicdicarboxylates with monomeric, 2D network and 3D framework structures

A series of new diorganotin and triorganotin(IV) heterocyclicdicarboxylates [(ⁿBu₃Sn)₂(2,5-pdc)]_∞ (1), {[(2-FC₆H₄CH₂)₃Sn]₂(2,5-pdc)}_∞ (2), {[(2-ClC₆H₄CH₂)₃Sn]₂(2,5-pdc)}_∞ (3), {[(4-CNC₆H₄CH₂)₃Sn]₂(2,5-pdc)}_∞ (4), {[(4-ClC₆H₄CH₂)₃Sn]₂(2,5-pdc)}_∞ (5), [(Ph)₂Sn(2,6-pdc)(H₂O)]_∞ (6), {[ⁿBu₃Sn(2,6-pdc)SnⁿBu₃]₂(H₂O)₂} · C₂H₃N (7) and {[Ph₃Sn(2,3-pdz)SnPh₃]₂(H₂O)} (8) have been obtained by reactions of diorganotin(IV) and triorganotin (IV) oxide with 2,6 or 2,5-H₂pdc (pdc = pyridinedicarboxylate) or 2,3-H₂pdz (pdz = pyrazinedicarboxylate). Complexes 1-8 were characterized by elemental, IR and NMR spectra analyses. The crystal and molecular structures of compounds 1, 6, 7 and 8 have been determined by X-ray single crystal diffraction. Compound 1 has 2D network structures. Compound 6 has 1D polymeric chain and 3D framework supramolecular structures due to the coordinated water molecules. Compound 7 has a monomeric structure, but the supramolecular structures are network.     

Versatility of pyridine-2-methanol as a chelating ligand toward a manganese ion: synthesis and X-ray structural analysis on some manganese-pyridine-2-methanol derivatives

A systematic synthesis and X-ray structural analysis have been made for several manganese derivatives with pyridine-2-methanol as a chelating ligand; neutral Mn(C₅NH₄-2-CH₂OH)₂(C₆F₅CO₂)₂ (1), trans-[Mn(C₅H₄N-2-CH₂-OH)₂{C₆F₄-1,4-(CO₂)₂}]_∞ (2), cis-[Mn(C₅H₄N-2-CH₂-OH)₂{C₆F₄-1,3-(CO₂)₂}]_∞ (3), {Mn(C₅H₄N-2-CH₂-OH)₂(4,4^′-bipyridine)(ClO₄)}_∞ (4), and Mn(C₅H₄N-2-CH₂-OH)₃(ClO₄)₂(4,4-azopiridine) (pyridine-2-methanol) (5) are our results. 1 and 5 are monomers, while 2-4 are polymers. An oxidation state of the manganese ion in 1, 2, 3, and 5 is 2⁺, while that of 4 is suggested to be 3⁺. The magnetic data of 4 down to 2 K are measured. The length of the linker ligand has been suggested to afford a crucial effect on the dimensionality of the product.     

Structural investigations on diorganotin and triorganotin(IV) phosphomycin derivatives

Four new diorganotin(IV), (R = Me, Bu), and triorganotin(IV), (R = Me, Ph), derivatives of the phosphomycin disodium salt antibiotic[(1R,2S)-1,2-epoxypropylphosphonate]Na₂ have been synthesized and their solid state configuration studied by X-ray crystallography, FT-IR, Mössbauer, UV-Vis spectroscopies. The X-ray diffraction investigation, performed on the bis[trimethyltin(IV)]phosphomycin, showed that the coordination geometry at all the Sn atoms is trigonal bipyramidal. The structure of the complex forms an unusual polymeric zig-zag planar network. The FT-IR and the ¹¹⁹Sn Mössbauer studies supported the formation of trigonal bipyramidal (Tbp) molecular structures, both in the diorganotin(IV) and triorganotin(IV) derivatives, even if, in the case of diorganotin(IV) derivatives, the tetrahedral structure cannot be a priori excluded. The group of phosphomycin coordinates the organotin(IV) centers originating a monodimensional polymeric network, as inferred by variable temperature ¹¹⁹Sn Mössbauer spectroscopy, used to investigate lattice dynamics of the bis-[trimethyltin(IV)]phosphomycin complex.     

Disubstituted diaryl diselenides inhibit δ-ALA-D and Na+, K+-ATPase activities in rat brain homogenates in vitro

Toxicological and pharmacological studies demonstrated that the introduction of functional groups into the aromatic ring of diphenyl diselenide alter its effect. The aim of this study was to evaluate the in vitro effect of m-trifluoromethyl-diphenyl diselenide (m-CF₃–C₆H₄Se)₂, p-chloro-diphenyl diselenide (p-Cl–C₆H₄Se)₂ and p-methoxyl-diphenyl diselenide (p-CH₃O–C₆H₄Se)₂ on δ-aminolevulinate dehydratase (δ-ALA-D) and Na⁺, K⁺-ATPase activities in rat brain homogenates. Diselenides inhibited δ-ALA-D activity (IC₅₀ 4–6 μM [concentration inhibiting 50%]), and dithiothreitol (DTT) restored the enzyme activity. ZnCl₂ (100 μM) did not restore δ-ALA-D inhibition caused by (p-Cl–C₆H₄Se)₂ and (m-CF₃–C₆H₄Se)₂. Na⁺, K⁺-ATPase activity was more sensitive to (p-Cl–C₆H₄Se)₂ and (m-CF₃–C₆H₄Se)₂ (IC₅₀ 6 μM) than (p-CH₃O–C₆H₄Se)₂ and (PhSe)₂ (IC₅₀ 45 and 31 μM, respectively). DTT restored the activity of Na⁺, K⁺-ATPase inhibited by diselenides. The effect of diselenides on Na⁺/K⁺-ATPase is dependent on their substitutions in the aromatic ring. The mechanism through which diselenides inhibit δ-ALA-D and Na⁺, K⁺-ATPase activities involves the oxidation of thiol groups.     

Synthesis and characterization of silver(I) derivatives containing acylpyrazolonate and phosphino ligands: X-ray crystal structures of monomeric [Ag(Q)(PPh3)2] and of dimeric [{Ag(Q)(PiBu3)}2] (Q = 1-phenyl-3-methyl-4-tert-butylacetylpyrazolon-5-ato)

New silver(I) acylpyrazolonate derivatives [Ag(Q)], [Ag(Q)(PR₃)]₂ and [Ag(Q)(PR₃)₂] (HQ = 1-R¹-3-methyl-4-R²(CO)pyrazol-5-one, HQ^Bn = R¹ = C₆H₅, R² = CH₂C₆H₅; HQ^CHPh2 = R¹ = C₆H₅, R² = CH(C₆H₅)₂; HQ^nPe = R¹ = C₆H₅, R² = CH₂C(CH₃)₃; HQ^tBu = R¹ = C₆H₅, R² = C(CH₃)₃; HQ^fMe = R¹ = C₆H₄-p-CF₃, R² = CF₃; HQ^fEt = R¹ = C₆H₅, R² = CF₂CF₃; R = Ph or iBu) have been synthesized and characterized in the solid state and solution. The crystal structure of 1-(4-trifluoromethylphenyl)-3-methyl-5-pyrazolone, the precursor of proligand HQ^fMe and of derivatives [Ag(Q^nPe)(PPh₃)₂] and [Ag(Q^nPe)(PiBu₃)]₂ have been investigated. [Ag(Q^nPe)(PPh₃)₂] is a mononuclear compound with a silver atom in a tetrahedrally distorted AgO₂P₂ environment, whereas [Ag(Q^nPe)(PiBu₃)]₂ is a dinuclear compound with two O₂N-exotridentate bridging acylpyrazolonate ligands connecting both silver atoms, their coordination environment being completed by a phosphine ligand.     

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.     

Syntheses and structural analyses of chiral rhenium containing amines of the formula (η-C5H5)Re(NO)(PPh3)((CH2)nNRR′) (n = 0, 1)

The reaction of the racemic chiral methyl complex (η⁵-C₅H₅)Re(NO)(PPh₃)(CH₃) (1) with CF₃SO₃H and then NH₂CH₂C₆H₅ gives [(η⁵-C₅H₅)Re(NO)(PPh₃)(NH₂CH₂C₆H₅)]⁺ ([4a-H]⁺; 73%), and deprotonation with t-BuOK affords the amido complex (η⁵-C₅H₅)Re(NO)(PPh₃)(NHCH₂C₆H₅) (76%). Reactions of 1 with Ph₃C⁺ X⁻ and then primary or secondary amines give [(η⁵-C₅H₅)Re(NO)(PPh₃)(CH₂NHRR′)]⁺ X⁻ ([6-H]⁺ X⁻; R/R′/X = a, H/NH₂CH₂C₆H₅/BF₄; a′, H/NH₂CH₂C₆H₅/PF₆; b, H/NH₂CH₂(CH₂)₂CH₃/PF₆; c, H/(S)-NH₂CH(CH₃)C₆H₅/BF₄); d, CH₂CH₃/CH₂CH₃/PF₆; e, CH₂(CH₂)₂CH₃/CH₂(CH₂)₂CH₃/PF₆; f, CH₂C₆H₅/CH₂C₆H₅/PF₆; g, -CH₂(CH₂)₂CH₂-/PF₆; h, -CH₂(CH₂)₃CH₂-/PF₆; i, CH₃/CH₂CH₂OH/PF₆ (62-99%). Deprotonations with t-BuOK afford the amines (η⁵-C₅H₅)Re(NO)(PPh₃)(CH₂NRR′) (6a-i; 99-40%), which are more stable and isolated in analytically pure form when R ≠ H. Enantiopure 1 is used to prepare (R_ReS_C)-[6c-H]⁺, (R_ReS_C)-6c, (S)-[6g-H]⁺, and (S)-6g. The crystal structures of [4a-H]⁺, a previously prepared NH₂CH₂Si(CH₃)₃ analog, [6a′,d,f,h-H]⁺, (R_ReS_C)-6c, and 6f are determined and analyzed in detail, particularly with respect to cation/anion hydrogen bonding and conformation. In contrast to analogous rhenium containing phosphines, 6a-i show poor activities in reactions that are catalyzed by organic amines.     

Semi-synthetic antibiotics: Titanium(IV), zirconium(IV) and mercury(II) complexes of 6-amino penicillinic acid

A number of organometallic derivatives involving 6-amino penicillinic acid (I), of the types η⁵-R)₂M- (Cl)L^?Et₃NH⁺ (II), (η⁵-R)₂M(Cl)L (III) and R′HgL [R = cyclopentadienyl (C₅H₅), indenyl (C₉H₇), R′ = phenyl (C₆H₅), p-acetoxyphenyl (p-CH₃COOC₆H₄), o-hydroxyphenyl (o-HOC₆H₄), p-hydroxyphenyl (p-HOC₆H₄); M = Ti(IV), Zr(IV); LH = 6-amino penicillinic acid] have been synthesized and characterized. Conductance measurements indicate that while the (η⁵-R)₂M(Cl)L^?Et₃NH⁺ complexes are 1:1 electrolytes, the remaining compounds are non-electrolytes. From IR and UV spectral studies it is concluded that the penicillin moiety is bidentate. PMR and CMR studies support the stoichiometry of the complexes. Fluorescence studies have been carried out for o- and p-HOC₆H₄HgL complexes and relevant photochemical parameters have been elucidated. X-ray diffraction studies have been made for the o-HOC₆H₄HgL complex. For the C₆H₅HgL, p-CH₃COOC₆H₄HgL and p-HOC₆H₄HgL complexes, thermal studies (TG and DTA) have been carried out and kinetic parameters for thermal degradation have been enumerated. In addition, the fragmentation pattern of these complexes has been analysed on the basis of mass spectra. The C₆H₅HgL and p-CH₃COOC₆H₄HgL complexes show positive bactericidal activities.     

Pyridine and phosphine reactions with [CPh3][B(C6F5)4]

Trityl borate salts [4-RPyCPh₃][B(C₆F₅)₄] (R = H 1, ^tBu 2, Et 3, NMe₂4) and [R₃PCPh₃][B(C₆F₅)₄] (R = Me 5, ⁿBu 6, Ph[1] 7, p-MeC₆H₄8) are readily prepared via equimolar reaction of the appropriate pyridine or phosphine and trityl borate [CPh₃][B(C₆F₅)₄]. The analogous reactions of PⁱPr₃ affords the product [(p-ⁱPr₃P-C₆H₄)Ph₂CH][B(C₆F₅)₄] (9) while the corresponding reactions of Cy₃P and ^tBu₃P gave the cyclohexadienyl derivatives [(p-R₃PC₆H₅)CPh₂][B(C₆F₅)₄] (R = Cy 10, ^tBu 11). X-ray structures of 5 and 9 are reported.