Synthesis and characterization of thiosemicarbazone derivatives of 2-ethoxy-3-methoxy-benzaldehyde and their rhenium(I) complexes

The ligands (HL¹, HL² and HL³) have been prepared and their reaction with fac-[ReX(CO)₃(CH₃CN)₂] (X = Br, Cl) in chloroform gave the adducts [ReX(CO)₃(HL)] (1a X = Cl, R = H; 1a′ X = Br, R = H; 1b X = Cl, R = CH₃; 1b′ X = Br, R = CH₃; 1c X = Cl, R = Ph; 1c′ X = Br, R = Ph) in good yield. All the compounds have been characterized by elemental analysis, mass spectrometry (FAB), IR and ¹H NMR spectroscopic methods, and the structures of the ligands have been elucidated by X-ray diffraction. In the case of HL¹, we have tried the reaction with [ReX(CO)₅] (X = Br, Cl) in toluene and we proved the formation of the adduct also by this way by the isolation of single crystals of 1a′ · ½C₇H_8.     

Syntheses and characterization of η-cyclopentadienyl and η-indenyl ruthenium(II) complexes of arylazoimidazoles: The molecular structure of the complex [(η-C5H5)Ru(PPh3)(C6H5-NN-C3H3N2)]

The complex [(η⁵-C₅H₅)Ru(PPh₃)₂Cl] (1) reacts with several arylazoimidazole (RaaiR′) ligands, viz., 2-(phenylazo)imidazole (Phai-H), 1-methyl-2-(phenylazo)imidazole (Phai-Me), 1-ethyl-2-(phenylazo)imidazole (Phai-Et), 2-(tolylazo)imidazole (Tai-H), 1-methyl-2-(tolylazo)imidazole (Tai-Me) and 1-ethyl-2-(tolylazo)imidazole (Tai-Et), gave complexes of the type [(η⁵-C₅H₅)Ru(PPh₃)(RaaiR′)]⁺ {where R, R′ = H (2), R = H, R′ = CH₃ (3), R = H, R′ = C₂H₅ (4), R = CH₃, R′ = H (5), R, R′ = CH₃ (6), R = CH₃, R′ = C₂H₅ (7)}. The complex [(η⁵-C₉H₇)Ru(PPh₃)₂(CH₃CN)]⁺ (8) undergoes reactions with a series of N,N-donor azo ligands in methanol yielding complexes of the type [(η⁵-C₉H₇) Ru(PPh₃)(RaaiR′)]⁺ {where R, R′ = H (9), R = H, R′ = CH₃ (10), R = CH₃, R′ = H (11), R = CH₃, R′ = C₂H₅ (12)}, respectively. These complexes were characterized by FT IR and FT NMR spectroscopy as well as by analytical data. The molecular structure of the complex [(η⁵-C₅H₅)Ru(PPh₃)(C₆H₅-NN-C₃H₃N₂)]⁺ (2) was established by single crystal X-ray diffraction study.     

New alkenyl-substituted group 4 C-ansa-metallocene complexes. Reactivity of the substituent at the carbon ansa bridge

The allyl-substituted group 4 metal complexes [M{(R)CH(η⁵-C₅Me₄)(η⁵-C₅H₄)}Cl₂] [M = Ti, R = CH₂CHCH₂, (2); R = CH₂C(CH₃)CH₂ (3); M = Zr, R = CH₂CHCH₂ (4), R = CH₂C(CH₃)CH₂ (5)] have been synthesized by the reaction of allyl ansa-magnesocene derivatives and the tetrachloride salts of the corresponding transition metal. The dialkyl complexes ] [M = Ti, R = CH₂=CHCH₂, R′ = Me (6), R′ = CH₂Ph (7); R = CH₂C(CH₃)CH₂, R′ = Me (8), R′ = CH₂Ph (9); M = Zr, R = CH₂CHCH₂, R′ = Me (10), R′ = CH₂Ph (11); R = CH₂C(CH₃)CH₂, R′ = Me (12), R′ = CH₂Ph (13)] have been synthesized by the reaction of the corresponding ansa-metallocene dichloride complexes 2-5 and two molar equivalents of the alkyl Grignard reagent. Compounds 2-5 reacted with H₂ under catalytic conditions (Wilkinson’s catalyst or Pd/C) to give the hydrogenation products [M{(R)CH(η⁵-C₅Me₄)(η⁵-C₅H₄)}Cl₂] [M = Ti and R = CH₂CH₂CH₃ (14) or R = CH₂CH(CH₃)₂ (15); M = Zr and R = CH₂CH₂CH₃ (16) or R = CH₂CH(CH₃)₂ (17)]. The reactivity of 2-5 has also been tested in hydroboration and hydrosilylation reactions. The hydroboration reactions of 3, 4 and 5 with 9-borabicyclo[3.3.1]nonane (9-BBN) yielded the complexes [M{(9-BBN)CH₂CH(R)CH₂CH(η⁵-C₅Me₄)(η⁵-C₅H₄)}Cl₂] [M = Ti and R = H (18); M = Zr and R = H (19) or R = CH₃ (20)]. The reaction with the silane reagents HSiMe₂Cl gave the corresponding [M{ClMe₂SiCH₂CHRCH₂CH(η⁵-C₅Me₄)(η⁵-C₅H₄)}Cl₂] [M = Ti and R = H (21); M = Zr and R = H (22) or R = CH₃ (23)]. The reaction of 22 with t-BuMe₂SiOH produced a new complex [Zr{t-BuMe₂SiOSi(Me₂)CH₂CH₂CH₂CH(η⁵-C₅Me₄)(η⁵-C₅H₄)}Cl₂] (24) through the formation of Si-O-Si bonds. On the other hand, reactivity studies of some zirconocene complexes were carried out, with the insertion reaction of phenyl isocyanate (PhNCO) into the zirconium-carbon σ-bond of [Zr{(n-Bu)CH(η⁵-C₅Me₄)(η⁵-C₅H₄)}₂Me₂] (25) giving [{(n-Bu)CH(η⁵-C₅Me₄)(η⁵-C₅H₄)]}Zr{Me{κ²-O,N-OC(Me)NPh}] as a mixture of two isomers 26a-b. The reaction of [Zr{(n-Bu)(H)C(η⁵-C₅Me₄)(η⁵-C₅H₄)}(CH₂Ph)₂] (27) with CO also provided a mixture of two isomers [{(n-Bu)CH(η⁵-C₅Me₄)(η⁵-C₅H₄)]}Zr(CH₂Ph){κ²-O,C-COCH₂Ph}] 28a-b. The molecular structures of 4, 11, 16 and 17 have been determined by single-crystal X-ray diffraction studies.     

Dimeric allylpalladium(II) complexes with pyrazolate bridges: Synthesis, characterization, structure and thermal behaviour

The synthesis, characterization and thermal behaviour of some new dimeric allylpalladium (II) complexes bridged by pyrazolate ligands are reported. The complexes ; R = H, R′ = C(CH₃)₃ (1b), R = H, R′ = CF₃ (1c); R = CH₃, R′ = CH(CH₃)₂ (2a); R = CH₃, R′ = C(CH₃)₃ (2b); and R = CH₃, R′ = CF₃ (2c)] have been prepared by the room temperature reaction of [Pd(η³-CH₂C(R)CH₂)(acac)](acac = acetylacetonate) with 3,5-disubstituted pyrazoles in acetonitrile solution. The complexes have been characterized by NMR (¹H, ¹³C{¹H}), FT-IR, and elemental analyses. The structure of a representative complex, viz. 2c, has been established by single-crystal X-ray diffraction. The dinuclear molecule features two formally square planar palladium centres which are bridged by two pyrazole ligands and the coordination of each metal centre is completed by allyl substituents. The molecule has non-crystallographic mirror symmetry. Thermogravimetric studies have been carried out to evaluate the thermal stability of these complexes. Most of the complexes thermally decompose in argon atmosphere to give nanocrystals of palladium, which have been characterized by XRD, SEM and TEM. However, complex 2c can be sublimed in vacuo at 2 mbar without decomposition. The equilibrium vapour pressure of 2c has been measured by the Knudsen effusion technique. The vapour pressure of the complex 2c could be expressed by the relation: ln (p/Pa)(±0.06) = −18047.3/T + 46.85. The enthalpy and entropy of vapourization are found to be 150.0 ± 3 kJ mol⁻¹ and 389.5 ± 8 J K⁻¹ mol⁻¹, respectively.     

New diruthenium vinyliminium complexes from the insertion of alkynes into bridging aminocarbynes

Primary alkynes R′CCH [R′ = Me₃Si, Tol, CH₂OH, CO₂Me, (CH₂)₄CCH, Me] insert into the metal-carbon bond of diruthenium μ-aminocarbynes [Ru₂{μ-CN(Me)(R)}(μ-CO)(CO)(MeCN)(Cp)₂][SO₃CF₃] [R = 2,6-Me₂C₆H₃ (Xyl), 1a; CH₂Ph (Bz), 1b; Me, 1c] to give the vinyliminium complexes [Ru₂{μ-η¹:η³-C(R′)CHCN(Me)(R)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] [R = Xyl, R′ = Me₃Si, 2a; R = Bz, R′ = Me₃Si, 2b; R = Me, R′ = Me₃Si, 2c; R = Xyl, R′ = Tol, 3a; R = Bz, R′ = Tol, 3b; R = Bz, R′ = CH₂OH, 4; R = Bz, R′ = CO₂Me, 5a; R = Me, R′ = CO₂Me, 5b; R = Xyl, R′ = (CH₂)₄CCH, 6; R = Xyl, R′ = Me, 7a; R = Bz, R′ = Me, 7b; R = Me, R′ = Me, 7c]. The related compound [Ru₂{μ-η¹:η³-C[C(Me)CH₂]CHCN(Me)(Xyl)}(μ-CO)(CO)(Cp)₂][SO₃CF₃], (9) is better prepared by reacting [Ru₂{μ-CN(Me)(Xyl)}(μ-CO)(CO)(Cl)(Cp)₂] (8) with AgSO₃CF₃ in the presence of HCCC(Me)CH₂ in CH₂Cl₂ at low temperature.In a similar way, also secondary alkynes can be inserted to give the new complexes [Ru₂{μ-η¹:η³-C(R′)C(R′)CN(Me)(R)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (R = Bz, R′ = CO₂Me, 11; R = Xyl, R′ = Et, 12a; R = Bz, R′ = Et, 12b; R = Xyl, R′ = Me, 13). The reactions of 2-7, 9, 11-13 with hydrides (i.e., NaBH₄, NaH) have been also studied, affording μ-vinylalkylidene complexes [Ru₂{μ-η¹:η³-C(R′)C(R″)C(H)N(Me)(R)}(μ-CO)(CO)(Cp)₂] (R = Bz, R′ = Me₃Si, R″ = H, 14a; R = Me, R′ = Me₃Si, R″ = H, 14b; R = Bz, R′ = Tol, R″ = H, 15; R = Bz, R′ = R″ = Et, 16), bis-alkylidene complexes [Ru₂{μ-η¹:η²-C(R′)C(H)(R″)CN(Me)(Xyl)}(μ-CO)(CO)(Cp)₂] (R′ = Me₃Si, R″ = H, 17; R′ = R″ = Et, 18), acetylide compounds [Ru₂{μ-CN(Me)(R)}(μ-CO)(CO)(CCR′)(Cp)₂] (R = Xyl, R′ = Tol, 19; R = Bz, R′ = Me₃Si, 20; R = Xyl, R′ = Me, 21) or the tetranuclear species [Ru₂{μ-η¹:η²-C(Me)CCN(Me)(Bz)}(μ-CO)(CO)(Cp)₂]₂ (23) depending on the properties of the hydride and the substituents on the complex. Chromatography of 21 on alumina results in its conversion into [Ru₂{μ-η³:η¹-C[N(Me)(Xyl)]C(H)CCH₂}(μ-CO)(CO)(Cp)₂] (22). The crystal structures of 2a[CF₃SO₃] · 0.5CH₂Cl₂, 12a[CF₃SO₃] and 22 have been determined by X-ray diffraction studies.     

The effect of polyether terminal chains in the liquid crystalline behavior of ortho-palladated complexes

A series of benzylideneanilines bearing terminal polyether chains, HL (HL = R-C₆H₄-CHN-C₆H₄-R′: R = OC₈H₁₇, R′ = O(CH₂CH₂O)₂C₂H₅; R = O(CH₂CH₂O)₂C₂H₅, R′ = OC₈H₁₇; R = R′ = O(CH₂CH₂O)₂C₂H₅; R = OC₁₂H₂₅, R′ = O(CH₂CH₂O)₃C₂H₅; R = O(CH₂CH₂O)₃C₂H₅, R′ = OC₁₂H₂₅; R = R′ = O(CH₂CH₂O)₃C₂H₅) have been prepared. Their dinuclear, [Pd(μ-X)L]₂ (X = OAc, Cl, Br, SC₈), [Pd₂(μ-SCn)(μ-X)L₂] (X = OAc, Cl; n = 8, 2) and mononuclear orthopalladated derivatives, Pd(acac)L, Pd(Ala)L, are reported and their mesogenic properties are compared with those of the analogous compounds with alkoxy chains. In general a great lowering in the melting points is produced for all the products. The free ligands and the alanine complexes are not liquid crystals. The chloro-bridged complexes bearing alkoxy and short polyether chains (O(CH₂CH₂O)₂C₂H₅) show the larger improvement of mesogenic properties. Longer polyether chains (O(CH₂CH₂O)₃C₂H₅) result usually in a destabilization of the mesophases. If only polyether chains are present, the destabilization is important regardless of the chain length. The ability of these molecules as ionic extractants and transporters was qualitatively evaluated for the more propitious cis-dinuclear complexes, which in fact showed some extracting ability, modest but improved compared to the free ligands.     

Olefin-aminocarbyne coupling in diiron complexes: Synthesis of new bridging aminoallylidene complexes

The bridging aminocarbyne complexes [Fe₂{μ-CN(Me)(R)}(μ-CO)(CO)₂(Cp)₂][SO₃CF₃] (R = Me, 1a; Xyl, 1b; 4-C₆H₄OMe, 1c; Xyl = 2,6-Me₂C₆ H₃) react with acrylonitrile or methyl acrylate, in the presence of Me₃NO and NaH, to give the corresponding μ-allylidene complexes [Fe₂{μ-η¹:η³- C_α(N(Me)(R))C_β(H)C_γ(H)(R′)}(μ-CO)(CO)(Cp)₂] (R = Me, R′ = CN, 3a; R = Xyl, R′ = CN, 3b; R = 4-C₆H₄OMe, R′ = CN, 3c; R = Me, R′ = CO₂Me, 3d; R = 4-C₆H₄OMe, R′ = CO₂Me, 3e). Likewise, 1a reacts with styrene or diethyl maleate, under the same reaction conditions, affording the complexes [Fe₂{μ-η¹:η³-C_α(NMe₂)C_β(R′)C_γ(H)(R″)}(μ-CO)(CO)(Cp)₂] (R′ = H, R″ = C₆H₅, 3f; R′ = R″ = CO₂Et, 3g). The corresponding reactions of [Ru₂{μ-CN(Me)(CH₂Ph)}(μ-CO)(CO)₂(Cp)₂][SO₃CF₃] (1d) with acrylonitrile or methyl acrylate afford the complexes [Ru₂{μ-η¹:η³-C_α(N(Me)(CH₂Ph))C_β(H)C_γ(H)(R′)}(μ-CO)(CO)(Cp)₂] (R′ = CN, 3h; CO₂Me, 3i), respectively.The coupling reaction of olefin with the carbyne carbon is regio- and stereospecific, leading to the formation of only one isomer. C-C bond formation occurs selectively between the less substituted alkene carbon and the aminocarbyne, and the C_β-H, C_γ-H hydrogen atoms are mutually trans.The reactions with acrylonitrile, leading to 3a-c and 3h involve, as intermediate species, the nitrile complexes [M₂{μ-CN(Me)(R)}(μ-CO)(CO)(NC-CHCH₂)(Cp)₂][SO₃CF₃] (M = Fe, R = Me, 4a; M = Fe, R = Xyl, 4b; M = Fe, R = 4-C₆H₄OMe, 4c; M = Ru, R = CH₂C₆H₅, 4d).Compounds 3a, 3d and 3f undergo methylation (by CH₃SO₃CF₃) and protonation (by HSO₃CF₃) at the nitrogen atom, leading to the formation of the cationic complexes [Fe₂{μ-η¹:η³-C_α(N(Me)₃)C_β(H)C_γ(H)(R)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (R = CN, 5a; R = CO₂Me, 5b; R = C₆H₅, 5c) and [Fe₂{μ-η¹:η³-C_α(N(H)(Me)₂)C_β(H)C_γ(H)(R)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (R = CN, 6a; R = CO₂Me, 6b; R = C₆H₅, 6c), respectively.Complex 3a, adds the fragment [Fe(CO)₂(THF)(Cp)]⁺, through the nitrile functionality of the bridging ligand, leading to the formation of the complex [Fe₂{μ-η¹:η³-C_α(NMe₂)C_β(H)C_γ(H)(CNFe(CO)₂Cp)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (9).In an analogous reaction, 3a and [Fe₂{μ-CN(Me)(R)}(μ-CO)(CO)₂(Cp)₂][SO₃CF₃], in the presence of Me₃NO, are assembled to give the tetrameric species [Fe₂{μ-η¹:η³-C_α(NMe₂)C_β(H)C_γ(H)(CN[Fe₂{μ- CN(Me)(R)}(μ-CO)(CO)(Cp)₂])}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (R = Me, 10a; R = Xyl, 10b; R = 4-C₆H₄OMe, 10c).The molecular structures of 3a and 3b have been determined by X-ray diffraction studies.     

Synthesis and protonolysis of neutral aluminum dihydride compounds stabilized by tridentate-substituted pyrrolyl ligands: Synthesis, structural characterization and ring-opening polymerization of ?-caprolactone

A series of aluminum compounds containing tridentate pyrrolyl ligands were obtained from related aluminum dihydride compounds via protonolysis. Treatment of tetranuclear aluminum compound [C₄H₂N{2,5-(CH₂NMe₂)₂}Al₂H₅]₂ (1) with two equivalents of [C₄H₃N{2,5-(CH₂NMe₂)₂}] in methylene chloride at 0 °C led to the formation of [C₄H₂N{2,5-(CH₂NMe₂)₂}]AlH₂ (2). Similarly, when the deuterated aluminum compound 1D was used, the corresponding aluminum compound [C₄H₂N{2,5-(CH₂NMe₂)₂}]AlD₂ (2D) could be isolated. The reaction of 2 with one or two equivalents of phenylethyne, triphenylmethanethiol, 2,6-diisopropylaniline, or triphenylsilanol generated mononuclear aluminum compounds [[C₄H₂N{2,5-(CH₂NMe₂)₂}]AlRR′ (3, R = -CCPh, R′ = H; 4, R = R′ = -CCPh; 5, R = -SCPh₃, R′ = H; 6, R = R′ = -SCPh₃; 7, R = -NH(2,6-ⁱPr₂Ph), R′ = H; 8, R = R′ = -NH(2,6-ⁱPr₂Ph); 9, R = -OSiPh₃, R′ = H; 10, R = R′ = -OSiPh₃). Related Al-D compounds of 3, 5, 7 and 9 were also synthesized and corresponding IR spectroscopic data well matched in comparison of the stretching frequencies of Al-H and Al-D. The molecular structures of 2D, 4, 5, 5D, 7, and 10 have been determined by X-ray crystallography. Compounds 2, 5, and 7 initiated the ring-opening polymerization of ?-caprolactone and produced high-molecular weight of poly-?-caprolactone.     

Dihalogen-halogenomethyl complexes of indium(III) X2InCH2X (X = Br, I): Simultaneous coordination of soft and hard ligands

Halogenomethyl-dihalogen-indium(III) compounds X₂InCH₂X (X = Br, I) obtained from indium monohalides and methylene dihalides were reacted with the soft donor ligands dialkylsulfides, R₂S (R = CH₃, CH₂Ph) to afford the corresponding dialkylsulfonium methylide complexes of InX₃, X₃InCH₂SR₂ (X = Br, R = CH₃, 1; X = I, R = CH₃, 2; X= I, R = CH₂Ph, 3). Compound 1 was reacted with the hard donor ligands dimethylsulfoxide or triphenylphosphine oxide to give the corresponding 1:1 adduct, Br₃(L)InCH₂S(CH₃)₂ (L = (CH₃)₂SO, 4; L = (C₆H₅)₃PO, 5). Compounds 1-5 were fully characterized in solution by NMR spectroscopy and in the solid state by X-ray methods.     

o-Phenylene-bridged Cp/amido titanium and zirconium complexes and their polymerization reactivity

o-Phenylene-bridged trimethylcyclopentadienyl/amido titanium complexes [(η⁵-2,3,5-Me₃C₅H)C₆H₄NR-κN]TiCl₂ (18, R = CH₃; 19, R = CH₂CH₃; 20, R = CH₂C(CH₃)₃; 21, R = CH₂(C₆H₁₁)) and zirconium complexes {[(η⁵-2,3,5-Me₃C₅H)C₆H₄NR-κN]ZrCl-μCl}₂ (22, R = CH₃; 23, R = CH₂CH₃; 24, R = CH₂C(CH₃)₃; 25, R = CH₂(C₆H₁₁); 26, R = C₆H₁₁; 27, R = CH(CH₂CH₃)₂) are prepared via a key step of the Suzuki-coupling reaction between 2-dihydroxyboryl-3-methyl-2-cyclopenten-1-one (2) and the corresponding bromoaniline compounds. The molecular structures of titanium complexes 18 and 19 and dinuclear zirconium complexes 24 and 26 were confirmed by X-ray crystallography. The Cp(centroid)-Ti-N and Cp(centroid)-Zr-N angles are smaller, respectively, than those observed for the Me₂Si-bridged complex [Me₂Si(η⁵-Me₄C₅)(N^tBu)]TiCl₂ and its Zr-analogue, indicating that the o-phenylene-bridged complexes are more constrained than the Me₂Si-bridged complex. Titanium complex 19 exhibits comparable activity and comonomer incorporation to the CGC ([Me₂Si(η⁵-Me₄C₅)(N^tBu)]TiCl₂) in ethylene/1-octene copolymerization. Complex 19 produces a higher molecular-weight polymer than CGC.     

Bis(2,4,6-triisopropylphenyl)tin(IV) compounds: Synthesis, single-crystal X-ray characterization and reactivity toward ionizing species and polar monomers

The synthesis of new organotin compounds of general formula Tip₂SnRR′ (Tip = 2,4,6-triisopropylbenzene; R = R′ = CH₃ (1); R = R′ = CHCH₂ (2); R = CH₂Ph, R′ = Br (3); R = R′ = CH₂CHCH₂ (4)) is described herein. The compounds have been characterized by ¹H, ¹³C, ¹¹⁹Sn NMR, mass spectroscopy and elemental analysis. Characterization by single-crystal X-ray diffraction analysis has been obtained for compounds 2, 3 and 4. The reactivity with ionizing agents has been studied by NMR spectroscopy. Compounds 2 and 4 underwent alkyl abstraction by [(CH₃CH₂)₃Si]⁺[B(C₆F₅)₄]⁻ affording stable cationic species (2a, 4a). For the cationic specie 4a a π-interaction of the benzyl group to the metal centre was recognized by solution NMR studies. A cationic species (3a) was generated from compound 3 using AgSbF₆ as ionizing agent. The cationic species (2a, 3a) exhibited moderate activity as initiator in the cationic polymerization of 1,4-butadiene and good activity in the ring opening polymerization (ROP) of propylene oxide and ε-caprolactone.     

Pentacoordination at antimony in dibenzostibocines via D–Sb transannular interactions (D = O,S): A structural study

Addition of M₂SCN(CH₂R)₂ to D(C₆H₄S)₂SbCl in methylene chloride solution leaded to the formation of the stable compounds D(C₆H₄S)₂SbS₂CN(CH₂R)₂ (D = O, R = Me, 1; D = S, R = Me, 2; R = Ph, 3). The new dibenzostibocines derivatives containing two different types of dithioligands were characterized by elemental analysis and spectroscopic studies (IR, ¹H and ¹³C NMR). Single crystal X-ray diffraction determinations of complexes 1–3 revealed that the antimony atom acts as an acceptor atom exhibiting an intramolecular transannular interaction with the donor D atom, expanding its coordination from three to five and displaying a skew trapezoidal local geometry.     

Novel generation ponytails in fluorous chemistry: Syntheses of primary, secondary, and tertiary (nonafluoro-tert-butyloxy)ethyl amines

(Nonafluoro-tert-butyloxy)ethyl tosylate 4 was prepared in 65% yield from nonafluoro-tert-butanol 1 using commercially available reagents. Further reaction of 4 with HNR¹R² (R¹ = R² = H, CH₃; R¹ = H, R² = CH₃, (CH₂)₃C₈F₁₇, CH₂CH₂OC(CF₃)₃) affords the appropriate (CF₃)₃COCH₂CH₂NR¹R² amines in 20-69% yields. Improved overall yields of [(CF₃)₃COCH₂CH₂]_3−nNR_n to 1 were obtained by the reaction of (CF₃)₃CONa 2 and (XCH₂CH₂)_3−nNR_n (X = Cl, n = 0, 1, 2, R = CH₃; X = CH₃SO₂O, n = 1, R = CH₃SO₂) nitrogen mustards and a similar reactive β-substituted ethyl amine. The title amines are mobile colorless liquids and volatile with steam. The bulky fluorous ponytail (CF₃)₃CO(CH₂)₂ displays high acidic stability and increases fluorous character almost as much as the classical straight-chain C₈F₁₇(CH₂)₃ ponytail.     

Organometallic emitting dyes: Palladium(II) nile red complexes

The Nile Red dye, H(NR), forms cyclometalated R₂-disubstituted-acetylacetonato square planar Pd(II) complexes (1-3; R = CH₃, CF₃, C₆H₅ respectively) whose photophysical properties were tested in cyclohexane, dichloromethane or methanol solutions. In cyclohexane 1-3 emit in the range 580-650 nm with a quantum yield ranging from 0.12 (R = CH₃) to 0.50 (R = CF₃) and lifetimes between 0.88 and 4.46 ns. These complexes form a new family of notably efficient red emitting organometallic dyes which could be of interest for practical applications.     

Zwitterionic diiron vinyliminium complexes: Alkylation, metalation and oxidative coupling at the S and Se functionalities

The zwitterionic vinyliminium complex [Fe₂{μ-η¹:η³-C(R′)C(S)CN(Me)(Xyl)}(μ-CO)(CO)(Cp)₂] (2a) (R′ = p-Me-C₆H₄ (Tol), Xyl = 2,6-Me₂C₆H₃) undergoes electrophilic addition at the S atom by HSO₃CF₃, MeSO₃CF₃, SiMe₃Cl, BrCH₂Ph, ICH₂CHCH₂ affording the complexes [Fe₂{μ-η¹:η³-C(Tol)C(SX)CN(Me)(Xyl)}(μ-CO)(CO)(Cp)₂][Y] (X =  H, Y = SO₃CF₃, 4a; X = Me, Y = SO₃CF₃, 4b; X = SiMe₃, Y = Cl, 4c; X = CH₂Ph, Y = Br, 4d; X = CH₂CHCH₂, Y = I, 4e).Compound 2a and the corresponding vinyliminium complexes 2b and 2c (R′ = CH₂OH, 2b; R′ = Me, 2c) react also with etherated BF₃ leading to the formation of the corresponding S-adducts [Fe₂{μ-η¹:η³-C(R′)C(SBF₃)CN(Me)(Xyl)}(μ-CO)(CO)(Cp)₂] (R′ = Tol, 5a; R′ = CH₂OH, 5b; R′ = Me, 5c).In analogous reactions, the zwitterionic vinyliminium complexes undergo S-metalation upon treatment with in situ generated [Fp]⁺[SO₃CF₃]⁻ [Fp = Fe(CO)₂(Cp)], leading to the formation of [Fe₂{μ-η¹:η³-C(R′)C(S-Fp)CN(Me)(Xyl)}(μ-CO)(CO)(Cp)₂][SO₃CF₃](R′ = CH₂OH, 6a; R′ = Me, 6b; R′ = Buⁿ, 6c).Similarly, zwitterionic vinyliminium containing Se in the place of S also undergo Se-electrophilic addition. Thus, the complexes [Fe₂{μ-η¹:η³-C(R′)C(SeX)CN(Me)(R)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (R = X = Me, R′ = Tol, 7a; R = Xyl, R′ = Me, X = Fp⁺, 7b) are obtained upon treatment of the neutral zwitterionic precursors with MeSO₃CF₃ and [Fp][SO₃CF₃], respectively.Alkylation at the S or Se atom of the bridging ligand is also accomplished by CH₂Cl₂, used as solvent, although the reaction is slower compared to more efficient alkylating reagents. The complexes formed by this route are [Fe₂{μ-η¹:η³-C(R′)C(E-CH₂Cl)CN(Me)(R)}(μ-CO)(CO)(Cp)₂][X] [E = S, R = Xyl, R′ = Tol, X = Cl, 8a; E = S, R = Xyl, R′ = Me, X = Cl, 8b; E = Se, R = R′ = Me, X = BPh₄, 8c].Finally, treatment of the zwitterionic vinyliminium complexes with I₂ results in the oxidative coupling with formation of S-S (disulfide) or Se-Se (diselenide) bond. The reactions, performed in the presence of NaBPh₄ afford the tetranuclear complexes [Fe₂{μ-η¹:η³-C(R′)C(E)CN(Me)(R)}(μ-CO)(CO)(Cp)₂]₂[BPh₄]₂ [R = Xyl, R′ = CH₂OH, E = S, 9a; R = Xyl, R′ = Me, E = S, 9b; R = Xyl, R′ = Buⁿ, E = S, 9c; R = Xyl, R′ = Me, E = Se, 9d; R = Me, R′ = Buⁿ, E = Se, 9e].The molecular structures of 4a, 8c and 9e have been determined by X-ray diffraction studies.     

Syntheses, X-ray structures and CVD studies of diorganoalkoxogallanes

Structural studies by X-ray crystallography have been carried out for a range of diorganoalkoxogallanes incorporating donor-functionalized ligands. The compounds [Et₂Ga(μ-OR)]₂ (1, R = CH₂CH₂NMe₂; 2, R = CH(CH₃)CH₂NMe₂; 3, C(CH₃)₂CH₂OMe; 4, R = CH(CH₂NMe₂)₂) adopt dimeric structures with a planar Ga₂O₂ ring, and each gallium atom is coordinated in a distorted trigonal bipyramidal geometry. Low pressure chemical vapor deposition (CVD) of 2 and 4 resulted in the formation of oxygen deficient gallium oxide thin films on glass. However, the reaction of Et₃Ga and ROH (R = CH₂CH₂NMe₂, CH(CH₃)CH₂NMe₂, C(CH₃)₂CH₂OMe, CH(CH₂NMe₂)₂) in toluene under aerosol assisted (AA)CVD conditions afforded stoichiometric Ga₂O₃ thin films on glass. This CVD technique offers a rapid, convenient route to Ga₂O₃, which involves the in situ formation of diethylalkoxogallanes, of the type [Et₂Ga(μ-OR)]₂, the structures of which are described in this paper. The gallium oxide films were deposited at 450 °C and analyzed by scanning electron microscopy (SEM), X-ray powder diffraction, wavelength dispersive analysis of X-rays (WDX), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy.     

C-C bond formation through olefin-thiocarbyne coupling in diiron complexes

The bridging diiron thiocarbyne complex [Fe₂{μ-CS(Me)}(μ-CO)(CO)₂(Cp)₂][SO₃CF₃] (1) reacts with activated olefins (methyl acrylate, acrylonitrile, styrene, diethyl maleate), in the presence of Me₃NO and NaH, to give the corresponding μ-allylidene complexes [Fe₂{μ-η¹:η³-C_α(SMe)C_β(R′)C_γ(H)(R″)} (μ-CO)(CO)(Cp)₂] (R″ = CO₂Me, R′ = H, 3a; R″ = CN, R′ = H, 3b; R″ = C₆H₅, R′ = H, 3c; R″ = R′ = CO₂Et, 3d). The coupling reaction of olefin with thiocarbyne is regio- and stereospecific, leading to the formation of only one isomer. C-C bond formation occurs between the less substituted alkene carbon and the thiocarbyne. Moreover, olefinic hydrogens of the bridging ligands are mutually trans.The reactions of 3a-b with MeSO₃CF₃ result, selectively, in the formation of the cationic μ-sulphonium allylidene complexes [Fe₂{μ-η¹:η³-C_α(SMe₂)C_β (H)C_γ(H)(R)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (R = CO₂Me, 4a; R = CN, 4b). Compound 4a undergoes displacement of the SMe₂ group by nucleophiles such as NaBH₄, NBu₄CN and NaOMe, affording the complexes [Fe₂{μ-η¹:η³-C_α(R)C_β (H)C_γ(H)(CO₂Me)}(μ-CO)(CO)(Cp)₂] (R = H, 5a; R = CN, 5b; R = OMe, 5c), respectively. The molecular structures of 3a and 5a have been determined by X-ray diffraction studies.     

Allylpalladium (II) complexes with dichalcogenoimidodiphosphinate ligands: Synthesis, structure, spectroscopy and their transformation into palladium chalcogenides

The synthesis, characterization and thermal behavior of new monomeric allylpalladium (II) complexes with dichalcogenoamidodiphosphinate anions are reported. The complexes [R = H, R′ = Prⁱ, E = S (1a); R = H, R′ = Prⁱ, E = Se (1b); R = H, R′ = Ph, E = S (1c); R = H, R′ = Ph, E = Se (1d); R = Me, R′ = Prⁱ, E = S (2a); R = Me, R′ = Prⁱ, E = Se (2b); R = Me, R′ = Ph, E = S (2c); R = Me, R′ = Ph, E = Se (2d)] have been prepared by room temperature reaction of [Pd(η³-CH₂C(R)CH₂)(acac)] (acac = acetylacetonate) with dichalcogenoimidodiphosphinic acids in acetonitrile solution. The complexes have been characterized by multinuclear NMR (¹H, ¹³C{¹H}, ³¹P{¹H}, ⁷⁷Se{¹H}), FT-IR and elemental analyses. The crystal structures of complexes 1a, 1d and 2d have been reported and they consist of a six-membered PdE₂P₂N ring (E = S for 1a and Se for 1d and 2d) and an allyl group, C₃H₄R(R = H for 1a and 1d and Me for 2d). Thermogravimetric studies have been carried out for few representative complexes. The complexes thermally decompose in argon atmosphere to leave a residue of palladium chalcogenides, which have been characterized by PXRD, SEM and EDS.     

Formation and structural characterization of mercury complexes from Te(R)CH2SiMe3 (R = Ph, CH2SiMe3) and HgCl2

The reaction of HgCl₂ and Te(R)CH₂SiMe₃ [R = CH₂SiMe₃ (1), Ph (2)] in ethanol yielded a mononuclear complex [HgCl₂{Te(R)CH₂SiMe₃}₂] (R = Ph, 3a; R = CH₂SiMe₃, 3b). The recrystallization of 3a or 3b from CH₂Cl₂ produced a dinuclear complex [Hg₂Cl₂(μ-Cl)₂{Te(R)CH₂SiMe₃}₂] (R = Ph, 4a; R = CH₂SiMe₃, 4b). When 3a was dissolved in CH₂Cl₂, the solvent quickly removed, and the solid recrystallized from EtOH, a stable ionic [HgCl{Te(Ph)CH₂SiMe₃}₃]Cl·2EtOH (5a·2EtOH) was obtained. Crystals of [HgCl₂{Te(CH₂SiMe)₂}]·2HgCl₂·CH₂Cl₂ (6b·2HgCl₂·CH₂Cl₂) were obtained from the CH₂Cl₂ solution of 3b upon prolonged standing. The complex formation was monitored by ¹²⁵Te-, and ¹⁹⁹Hg NMR spectroscopy, and the crystal structures of the complexes were determined by single crystal X-ray crystallography.