η-Alkynyl and vinylidene transition metal complexes: 10. Reaction of the metal-acetylide [(η-C5H5)(CO)(NO)W---CC---C(CH3)3]Li with 1,2-diiodoethane as electrophile and with various nucleophiles

Treatment of the η¹-acetylide complex [(η⁵-C₅H₅)(CO)(NO)W---CC---C(CH₃)₃]Li (4) with 1,2-diiodoethane in THF at −78 °C, followed by the addition of Li---CC---R [R=C(CH₃)₃, C₆H₅, Si(CH₃)₃, 6a–6c] or n-C₄H₉Li and protonation with H₂O, afforded the corresponding oxametallacyclopentadienyl complexes (η⁵-C₅H₅)W(I)(NO)[η²-O=C(CC---R)CH=CC(CH₃)₃] (7a–7c), 8c and (η⁵-C₅H₅)W(I)(NO)[η²-O=C(n-C₄H₉)CH=CC(CH₃)₃] (9). The formation of these metallafuran derivatives is rationalized by the electrophilic attack of 1,2-diiodoethane onto the metal center of 4 to form first the neutral complex [(η⁵-C₅H₅)(I)(CO)(NO)W---CC---C(CH₃)₃] (5). Subsequent nucleophilic addition of Li---CC---R 6a–6c or n-C₄H₉Li and a reductive elimination step followed by protonation leads to the products 7a–7c and 9. One reaction intermediate could be trapped with CF₃SO₃CH₃ and characterized by a crystal structure analysis. The identity of another intermediate was established by infrared spectroscopic data. The oxametallacyclopentadienyl complex 10 forms in the presence of excess 1,2-diiodoethane through an alternative pathway and crystallizes as a clathrate containing iodine.     

Alkyloxy- and aryloxy-titanocenes: Synthesis, solid-state structure and cyclic voltammetric studies

Alkyloxy- and aryloxy-functionalized titanocenes of type [Ti](Cl)(OR) (R = Me (2), CH₂PPh₂ (3), CH₂Fc (4), C₆H₅ (5), C₆H₄-4-CN (6), C₆H₄-4-NO₂ (7), C₆H₄-4-Me (8), C₆H₄-4-OMe (9), C₆H₄-4-C(O)Me (10), C₆H₄-4-CO₂Me (11), C₆H₄-3-NO₂ (12); [Ti] = (η⁵-C₅H₄SiMe₃)₂Ti; Fc = (η⁵-C₅H₄)(η⁵-C₅H₅)Fe) were synthesized by the reaction of [Ti]Cl₂ (1) with ROH in a 1:1 molar ratio and in presence of Et₂NH. Diaryloxy-titanocenes (e.g., [Ti](OC₆H₄-4-NO₂)₂ (13)) are accessible, when the ratio of 1 and ROH is changed to 1:2. This synthesis methodology also allowed the preparation of dinuclear complexes of composition ([Ti](Cl))₂(μ-OC₆H₄O) (14) and ([Ti](Cl)(μ-OC₆H₄-4))₂ (15) by the reaction of 1 with hydroquinone or 1,1′-dihydroxybiphenyl in a 2:1 stoichiometry.Cyclic voltammetric studies show the characteristic [Ti(IV)/Ti(III)] reductions. It was found that the potentials of the alkyloxy titanocenes 2–4 do not differ, while for the aryloxy-titanocenes 5–15 the reduction potentials correlate linearly with the σ_p/m Hammett substituent constants showing a strong influence of the substituents on the electron density at titanium.The structures of titanocenes 4, 5, 9, and 11–13 in the solid state are reported. Typical for these organometallic sandwich compounds is a distorted tetrahedral coordination geometry around titanium with D1–Ti–D2 angles (D1, D2 = centroids of the cyclopentadienyl ligands) of ca. 130 °. In comparison to FcCH₂O-functionalized 4, for the aryloxy-titanocenes 5, 9, and 11–13 a significant larger Ti–O–C angle was found confirming electronic interactions between the titanium atom and the appropriate aryl group.     

Complexes containing the unit Rh2 P PM (M = Cr or Mn, P P = bis(diphenylphosphino) alkane); the independence of the metal centres

Treatment of (η⁵-C₅H₅)₂Rh₂(CO)η¹-Ph₂P(CH₂)_n PPh₂(μ-η¹:η¹-CF₃C₂CF₃) (I) with (η⁵-CH₃C₅H₄)Mn(CO)₂(thf) or Cr(CO)₅(thf) gives the hetero-trinuclear products (η-C₅H₅)₂Rh₂(CO)(μ-CF₃C₂CF₃)μ:η¹:η¹-Ph₂P(CH₂)_nPPh₂(η-CH₃C₅H₃C₄)Mn(CO₂) (II, n = 1–4) and (η⁵-C₅H₅)₂Rh₂(CO)(μ-CF₃C₂CF₃)μ:η¹:η¹-Ph₂P(CH₂)nPPh₂Cr(CO)₅ (IV, n = 1–4) in good yields. In these products, the configuration of the CO and bisphosphine units on the Rh-Rh bond is trans. Related reactions between (η⁵:η⁵-C₅H₄CH₂C₅H₄)Rh₂(CO)η¹-Ph₂P(CH₂)nPPh₂(μ-η¹:η¹- (V) and the same solvated manganese and chromium complexes give (η⁵:η⁵-C₅H₄CH₂C₅H₄)Rh₂(CO)(μ-CF₃C₂CF₃)μ:η¹:η¹-Ph₂P(CH₂) (VI, n = 1, 2 or 4) and (η⁵:η⁵-C₅H₄CH₂C₅H₄)Rh₂(CO)(μ-CF₃C₂CF₃)μ:η¹:η¹-Ph₂P(CH₂) (VIII). The complexes (VI) and (VIII) have a mutually cis arrangement of CO and the bisphosphine on the Rh-Rh bond. Attempts to induce the complexes (IV), (V), (VI), and (VIII) to form clusters by loss of CO and Rh-M bond formation were not successful. Treatment with trimethylamine oxide or sunlight irradiation generally resulted in loss of the hetero-metal and formation of the dirhodium phosphine oxide complexes (III, n = 2 or 4) and (VII, n = 2, 3).     

New dimeric and supramolecular organotin(IV) complexes with a tridentate schiff base as potential biocidal agents

The paper describes the synthesis and structural characterization of six new diorganotin(IV) compounds 1–6, [R₂SnL] and a monoorganotin(IV) derivative, C₄H₉SnClL (7). Here L = N′-(5-bromo-2-oxidobenzylidene)-N-(oxidomethylene)hydrazine ligand with ONO tridentate chelation capability and R = CH₃ (1), C₂H₅ (2), n-C₄H₉ (3), C₆H₅ (4), C₈H₁₇ (5), tert-C₄H₉ (6), The packing diagram offers a supramolecular structure for 1 and a dimeric structure for 4 with distorted square-pyramidal and distorted trigonal geometry, respectively. The different geometry of 1 than 4 can be attributed to the presence of intermolecular non-covalent Sn---O and Sn---H interactions in the former. The antifungal, antibacterial, antiurease and antileishmanial activities of these complexes proved them to be active biologically and may be formulated as new metal-based drugs in future.     

Supramolecular organotin(IV) dithiocarboxylates as potential antimicrobial agents

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

Syntheses, crystal structure and electrochemical characterization of ferrocene-containing nickel(II) complexes with 4,11-dihydro-5,7,12,14-tetramethyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecine

In the title complexes, {[(η-C₅H₅)Fe(η-C₅H₄)(CO)](C₂₂H₂₁N₄)Ni} (1) and {[(η-C₅H₅)Fe(η-C₅H₄)(CO)]₂(C₂₂H₂₀N₄)Ni} (2), one and two electroactive ferrocenes (Fc) were grafted onto the methine of the nickel complex Nitmtaa (H₂tmtaa = 4,11-dihydro-5,7,12,14-tetramethyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecine) through the carbonyl groups. The two new complexes were characterized by IR, UV, MS and NMR spectra as well as by DSC measurements. The crystal structure of 1 was determined. Ni coordinates to four nitrogen atoms of tmtaa, and it is almost in the same plane as the N₄ plane. The mean Ni–N bond distance in the N₄ plane is 1.866 Å. The non-planar, saddle-shaped conformation of H₂tmtaa is almost retained in the nickel complex. The symmetry axis of ferrocene is almost parallel to the N₄ plane in Nitmtaa. The dihedral angle between the N₄ plane in Nitmtaa and the cyclopentadienyl ring in ferrocene is 98.5°. The electrochemistry of 1 and 2 was studied by cyclic voltammetry in CH₂Cl₂/1 × 10⁻¹ M n-Bu₄NClO₄ using a glass carbon working electrode. Because of the electron transfer between the electroactive ferrocene and the completely conjugated system of Nitmtaa, the complexes show novel electrochemical properties and the ferrocenes in 1 and 2 act as electron acceptors.     

Alcohol adducts of zinc dichloride: Molecular structure of [ZnCl2(THF){1-HOC(C6H11)2-2-NMe2C6H4}]

The aminoalcohols 1-HOCR₂-2-NMe₂C₆H₄ [R = Ph (1), R = C₆H₁₁ (2)] and 1-HOCPh₂CH₂-2-NMe₂C₆H₄ (3) react with ZnCl₂ in tetrahydrofuran to give the alcohol adducts [ZnCl₂(THF){1-HOCR₂-2-NMe₂C₆H₄}] [R = Ph (4), R = C₆H₁₁ (5)] and [ZnCl₂(THF){1-HOCPh₂CH₂-2-NMe₂C₆H₄}] (6). The complexes 4–6 were characterized by ¹H and ¹³C NMR spectroscopy, and 5 was also structurally characterized by X-ray crystallography.     

Formal chromium–chromium triple bonds and bent rings in the binuclear cycloheptatrienylchromium carbonyls (C7H7)2Cr2(CO)n (n = 6, 5, 4, 3, 2, 1, 0): A density functional theory study

Binuclear cycloheptatrienylchromium carbonyls of the type (C₇H₇)₂Cr₂(CO)_n (n = 6, 5, 4, 3, 2, 1, 0) have been investigated by density functional theory. Energetically competitive structures with fully bonded heptahapto η⁷-C₇H₇ rings are not found for (C₇H₇)₂Cr₂(CO)_n structures having two or more carbonyl groups. This result stands in contrast to the related (C_nH_n)₂M₂(CO)_n (M = Mn, n = 6; M = Fe, n = 5; M = Co, n = 4) systems. Most of the predicted (C₇H₇)₂Cr₂(CO)_n structures have bent trihapto or pentahapto C₇H₇ rings and CrCr distances in the range 2.4–2.5 Å suggesting formal triple bonds. In some cases rearrangement of the heptagonal C₇H₇ ring to a tridentate cyclopropyldivinyl or tridentate bis(carbene)alkyl ligand is observed. In addition structures with CO insertion into the C₇H₇–Cr bond are predicted for (C₇H₇)₂Cr₂(CO)_n (n = 6, 4, 2). The global minima found for the (C₇H₇)₂Cr₂(CO)_n derivatives for n = 6, 5, and 4 are (η⁵-C₇H₇)(OC)₂CrCr(CO)₄(η¹-C₇H₇), (η³-C₇H₇)(OC)₂CrCr(CO)₃(η^2,1- C₇H₇), and (η⁵-C₇H₇)₂Cr₂(CO)₄, respectively. The global minima for (C₇H₇)₂Cr₂(CO)_n (n = 3, 2) have rearranged C₇H₇ groups. Singlet and triplet structures with heptahapto η⁷-C₇H₇ rings are found for the dimetallocenes (η⁷-C₇H₇)₂Cr₂(CO) and (η⁷-C₇H₇)₂Cr₂, with the singlet structures being of much lower energies in both cases.     

Lithiated γ-O-functionalized propyl phenyl sulfides and sulfones of the type Li[CH(SOxPh)CH2CH2OR] (x = 0, 2). [Li{CH(SPh)CH2CH2Ot-Bu}(tmeda)] – A structurally characterized organolithium inner complex

Lithiation of O-functionalized alkyl phenyl sulfides PhSCH₂CH₂CH₂OR (R = Me, 1a; i-Pr, 1b; t-Bu, 1c; CPh₃, 1d) with n-BuLi/tmeda in n-pentane resulted in the formation of α- and ortho-lithiated compounds [Li{CH(SPh)CH₂CH₂OR}(tmeda)] (α-2a–d) and [Li{o-C₆H₄SCH₂CH₂CH₂OR)(tmeda)] (o-2a–d), respectively, which has been proved by subsequent reaction with n-Bu₃SnCl yielding the requisite stannylated γ-OR-functionalized propyl phenyl sulfides n-Bu₃SnCH(SPh)CH₂CH₂OR (α-3a–d) and n-Bu₃Sn(o-C₆H₄SCH₂CH₂CH₂OR) (o-3a–d). The α/ortho ratios were found to be dependent on the sterical demand of the substituent R. Stannylated alkyl phenyl sulfides α-3a–c were found to react with n-BuLi/tmeda and n-BuLi yielding the pure α-lithiated compounds α-2a–c and [Li{CH(SPh)CH₂CH₂OR}] (α-4a–b), respectively, as white to yellowish powders. Single-crystal X-ray diffraction analysis of [Li{CH(SPh)CH₂CH₂Ot-Bu}(tmeda)] (α-2c) exhibited a distorted tetrahedral coordination of lithium having a chelating tmeda ligand and a C,O coordinated organyl ligand. Thus, α-2c is a typical organolithium inner complex.Lithiation of O-functionalized alkyl phenyl sulfones PhSO₂CH₂CH₂CH₂OR (R = Me, 5a; i-Pr, 5b; CPh₃, 5c) with n-BuLi resulted in the exclusive formation of the α-lithiated products Li[CH(SO₂Ph)CH₂CH₂OR] (6a–c) that were found to react with n-Bu₃SnCl yielding the requisite α-stannylated compounds n-Bu₃SnCH(SO₂Ph)CH₂CH₂OR (7a–c). The identities of all lithium and tin compounds have been unambiguously proved by NMR spectroscopy (¹H, ¹³C, ¹¹⁹Sn).     

Effect of chelating agent on the oxidation rate of PCP in the magnetite/H2O2 system at neutral pH

The complex [Rh(CO)₂Cl]₂ reacts with two molar equivalent of pyridine carboxylic acids ligands Py-2-COOH(a), Py-3-COOH(b) and Py-4-COOH(c) to yield rhodium(I) dicarbonyl chelate complex [Rh(CO)₂(L^/)](1a) {L^/ = η²-(N,O) coordinated Py-2-COO⁻(a^/)} and non-chelate complexes [Rh(CO)₂ClL^//](1b,c) {L^// = η¹-(N) coordinated Py-3-COOH(b), Py-4-COOH(c)}. The complexes 1 undergo oxidative addition (OA) reactions with different electrophiles such as CH₃I, C₂H₅I, C₆H₅CH₂Cl and I₂ to give penta coordinated Rh(III) complexes of the types [Rh(CO)(CORⁿ)XL^/], {n = 1,2,3; R¹ = CH₃(2a); R² = C₂H₅(3a); X = I and R³ = CH₂C₆H₅ (4a); X = Cl}, [Rh(CO)I₂L^/](5a), [Rh(CO)(CORⁿ)ClXL^//] {R¹ = CH₃(6b,c); R² = C₂H₅(7b,c); X = I and R³ = CH₂C₆H₅ (8b,c); X = Cl} and [Rh(CO)ClI₂L^//](9b,c). The complexes have been characterized by elemental analysis, IR and ¹H NMR spectroscopy. Kinetic data for the reaction of 1a–b with CH₃I indicate a first order reaction. The catalytic activity of 1a–c for the carbonylation of methanol to acetic acid and its ester is evaluated and a higher turn over number (TON = 810–1094) is obtained compared with that of the well-known commercial species [Rh(CO)₂I₂]⁻ (TON = 653) at mild reaction conditions (temperature 130 ± 5 °C, pressure 35 ± 5 bar).     

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.     

Preparation of new dinuclear half-titanocene complexes with ortho- and meta-xylene linkages and investigation of styrene polymerization

Half-titanocene is well-known as an excellent catalyst for the preparation of SPS (syndiotactic polystyrene) when activated with methylaluminoxane (MAO). Dinuclear half-sandwich complexes of titanium bearing a xylene bridge, (TiCl₂L)₂{(μ-η⁵, η⁵-C₅H₄-ortho-(CH₂–C₆H₄–CH₂)C₅H₄}, (4 (L = Cl), 7 (L = O-2,6-iPr₂C₆H₃)) and (TiCl₂L)₂{(μ-η⁵, η⁵-C₅H₄-meta-(CH₂–C₆H₄–CH₂)C₅H₄} (5 (L = Cl), 8(L = O-2,6-iPr₂C₆H₃)), have been successfully synthesized and introduced for styrene polymerization. The catalysts were characterized by ¹H- and ¹³C NMR, and elemental analysis. These catalysts were found to be effective in forming SPS in combination with MAO. The activities of the catalysts with rigid ortho- and meta-xylene bridges were higher than those of catalysts with flexible pentamethylene bridges. The catalytic activity of four dinuclear half-titanocenes increased in the order of 4 < 5 < 7 < 8. This result displays that the meta-xylene bridged catalyst is more active than the ortho-xylene bridged and that the aryloxo group at the titanium center is more effective at promoting catalyst activity compared to the chloride group at the titanium center. Temperature and ratio of [Al]:[Ti] had significant effects on catalytic activity. Polymerizations were conducted at three different temperatures (25, 40, and 70 °C) with variation in the [Al]:[Ti] ratio from 2000 to 4000. It was observed that activity of the catalysts increased with increasing temperature, as well as higher [Al]:[Ti]. Different xylene linkage patterns (ortho and meta) were recognized to be a principal factor leading to the characteristics of the dinuclear catalyst due to its different spatial arrangement, causing dissimilar intramolecular interactions between the two active sites.     

NMR,IR and DFT studies of phenylplatinum complexes with O-monodentate coordinated silsesquioxanate and auxiliary phosphine ligands

The molecular structure and spectroscopic properties of a series of phenylplatinum complexes containing silsesquioxanate and phosphine ligands with general formula trans-[Pt{O₁₀Si₇(R)₇(OH)₂}(Ph)(L)₂] (1: R = cyclo-C₅H₉, L = PEt₃; 2: R = iso-C₄H₉, L = PEt₃; 3: R = CH₃, L = PEt₃; 4: R = cyclo-C₅H₉, L = PMe₃; 5: R = cyclo-C₅H₉, L = PMe₂Ph; 6: R = cyclo-C₅H₉, L = PPh₂Me; 7: R = cyclo-C₅H₉, L = PPh₃) have been investigated by DFT/OPW91/6-31G(d) calculations, ¹H, ¹³C, ²⁹Si and ³¹P NMR and IR spectroscopy. DFT molecular modeling based on available X-ray and NMR data for complexes 1 and 2 allowed deriving structure-NMR spectra correlations. It was found that the alkyl substituents (R) attached to Si atoms, cyclo-C₅H₉, iso-C₄H₉ and CH₃, slightly influence the geometry and multinuclear NMR parameters of the complexes in the series studied. The molecular structures of the Pt(II) complexes with R = cyclo-C₅H₉ (4–7) were predicted by DFT calculations of their simplified models with R = CH₃ (4′?7′). The geometry optimizations of 4′?7′ showed square-planar configuration of Pt(II) center bonded to two trans phosphine ligands, a phenyl group and an O-monocoordinated silsesquioxanate. The structures 4′?6′ are stabilized by two intramolecular hydrogen bonds similar to 1 and 2. A fast conformer exchange process A?B and switching of H-bonds in solution of 1–6 were suggested based on (i) the calculated conformer energies and small barrier of the process, and (ii) the observed single ¹H NMR signal at low magnetic field. The stability of the Pt(II) complexes depends on the nature of the phosphine ligands and decreases in the order PMe₂Ph > PMe₃ > PPh₂Me > PEt₃ > PPh₃. The PPh₃ ligands attached to Pt(II) in 7 cause the largest geometry changes and a new set of weaker hydrogen bonds. The comparison of the calculated NMR and IR parameters with the experimental spectroscopic data reveals good coincidence and thus confirmed the suggested molecular structures.     

Rhodium(I) carbonyl complexes of chalcogen functionalized tripodal phosphines, [CH3C(CH2P(X)Ph2)3] {X = O, S, Se} and their reactivity

The reaction of dimeric rhodium precursor [Rh(CO)₂Cl]₂ with two molar equivalent of 1,1,1-tris(diphenylphosphinomethyl)ethane trichalcogenide ligands, [CH₃C(CH₂P(X)Ph₂)₃](L), where X = O(a), S(b) and Se(c) affords the complexes of the type [Rh(CO)₂Cl(L)] (1a–1c). The complexes 1a–1c have been characterized by elemental analyses, mass spectrometry, IR and NMR (¹H, ³¹P and ¹³C) spectroscopy and the ligands a–c are structurally determined by single crystal X-ray diffraction. 1a–1c undergo oxidative addition (OA) reactions with different electrophiles such as CH₃I, C₂H₅I and C₆H₅CH₂Cl to give Rh(III) complexes of the types [Rh(CO)(COR)ClXL] {R = –CH₃ (2a–2c), –C₂H₅ (3a–3c); X = I and R = –CH₂C₆H₅ (4a–4c); X = Cl}. Kinetic data for the reaction of a–c with CH₃I indicate a first-order reaction. The catalytic activity of 1a–1c for the carbonylation of methanol to acetic acid and its ester is evaluated and a higher turn over number (TON = 1564–1723) is obtained compared to that of the well-known commercial species [Rh(CO)₂I₂]⁻ (TON = 1000) under the reaction conditions: temperature 130 ± 2 °C, pressure 30 ± 2 bar and time 1 h.     

The synthesis, structure and reactivity of aldehyde substituted η-allylic complexes of molybdenum

Reaction of cis-[Mo(NCMe)₂(CO)₂(η⁵-L)][BF₄] (L=C₅H₅ or C₅Me₅) with 1-acetoxybuta-1,3-diene gives the cationic complexes [Mo{η⁴-syn-s-cis-CH₂CHCHCH(OAc)}(CO)₂(η⁵-L)][BF₄], which, on reaction with aqueous NaHCO₃/CH₂Cl₂, afford good yields of the anti-aldehyde substituted complexes [Mo{η³-exo-anti-CH₂CHCH(CHO)}(CO)₂(η⁵-L)] 2 (L=C₅Me₅), 4 (L=C₅H₅)]. The corresponding η⁵-indenyl substituted complex 5 was prepared by protonation (HBF₄·OEt₂) of [Mo(η³-C₃H₅)(CO)₂(η⁵-C₉H₇)] followed by addition of CH₂=CHCH=CH(OAc) and hydrolysis (aq. NaHCO₃/CH₂Cl₂). An X-ray crystallographic study of complex 2 confirmed the structure and showed that there is a contribution from a zwitterionic form involving donation of electron density from the molybdenum to the aldehyde carbonyl group. Treatment of 2 and 4, in methanol solution, with NaBH₄ afforded the alcohols [Mo{η³-exo-anti-CH₂CHCHCH₂(OH)}(CO)₂(η⁵-L)] [6 (L=C₅H₅), 8 (L=C₅Me₅)]; however, prolonged (30 h) reaction with NaBH₄/MeOH surprisingly gave good yields of the methoxy-substituted complexes [Mo{η³-exo-anti-CH₂CHCHCH₂(OMe)}(CO)₂(η⁵-L)] [7 (L=C₅H₅), 9 (L=C₅Me₅)], the structure of 7 being confirmed by single crystal X-ray crystallography. This methoxylation reaction can be explained by coordination of the hydroxyl group present in 6 and 8 onto B₂H₆ to form the potential leaving group HOBH₃⁻, which on ionisation affords [Mo(η⁴-exo-buta-1-3-diene)(CO)₂(η⁵-L)]⁺ which is captured by reaction with OMe⁻. Complex 8 is also formed in good yield on reaction of 2 with HBF₄·OEt₂ followed by treatment of the resulting cation [Mo{η⁴-exo-s-cis-syn-CH₂CHCHCH(OH)}(CO)₂(η⁵-C₅Me₅)][BF₄] with Na[BH₃CN]. Reaction of 4 with the Grignard reagents MeMgI, EtMgBr or PhMgCl afforded moderate yields of the alcohols [Mo{η³-exo-anti-CH₂CHCHCH(OH)R}(CO)₂(η⁵-C₅H₅)] [11 (R=Me), 12 (R=Et), 13 (R=Ph)]. Similarly, treatment of 2 with MeLi gave the corresponding alcohol 14. An attempt to carry out the Oppenauer oxidation [Al(OPr′)₃/Me₂CO] of 11 resulted in an elimination reaction and the formation of the η³-s-pentadienyl complex [Mo{η³-exo-anti-CH₂CHCH(CHCH₂)}(CO)₂(η⁵-C₅H₅)], which was structurally identified by X-ray crystallography. Interestingly, oxidation of 6 with [Bu₄ⁿN][RuO₄]/morpholine-N-oxide affords the aldehyde complex, 4 in good yield. Finally, reaction of 11 with [NO][BF₄] followed by addition of Na₂CO₃ affords the fur-3-ene complex [Mo{η²-

(H)Me}(CO)(NO)(η⁵-C₅H₅)].     

Syntheses and structures of doubly tucked-in titanocene complexes with tetramethyl(aryl)cyclopentadienyl ligands

Titanocene–bis(trimethylsilyl)ethyne complexes [Ti(η⁵-C₅Me₄R)₂(η²-Me₃SiCCSiMe₃)], where R=benzyl (Bz, 1a), phenyl (Ph, 1b) and p-fluorophenyl (FPh, 1c), thermolyse at 150–160°C to give products of double C---H activation [Ti(η⁵-C₅Me₄Bz){η³:η⁴-C₅Me₃(CH₂)(CHPh)}] (2a), [Ti(η⁵-C₅Me₄Bz){η³:η⁴-C₅Me₂Bz(CH₂)₂}] (2a′), [Ti(η⁵-C₅Me₄Ph){η³:η⁴-C₅Me₂Ph(CH₂)₂}] (2b), and [Ti(η⁵-C₅Me₄FPh){η³:η⁴-C₅Me₂FPh(CH₂)₂}] (2c). In the presence of 2,2,7,7-tetramethylocta-3,5-diyne (TMOD) the thermolysis affords analogous doubly tucked-in compounds bearing one η³:η⁴-allyldiene and one η⁵-C₅Me₄R ligand having TMOD attached by its C-3 and C-6 carbon atoms to the vicinal methylene groups adjacent to the substituent R (R=Bz (3a), Ph (3b), and FPh (3c)). Compound 3a is smoothly converted into air-stable titanocene dichloride [TiCl₂{η⁵-C₅Me₂Bz(CH₂CH(t-Bu)CH=CHCH(t-Bu)CH₂)}(η⁵-C₅Me₄Bz)] (4a) by a reaction with hydrogen chloride. Yields in both series of doubly tucked-in complexes decrease in the order of substituents: BzPh>FPh. Crystal structures of 1c, 2a, 2b, and 3b have been determined.     

Cobalt bis(dicarbollide) ions functionalized by CMPO-like groups attached to boron by short bonds; efficient extraction agents for separation of trivalent f-block elements from highly acidic nuclear waste

New boron substituted cobalta bis(dicarbollide)(1-) ion (1) derivatives of formula [(8,8′-(RPhP(O)(CH₂)nC(O)N) < (1,2-C₂B₉H₁₀)₂-3,3′-Co]⁻ (R = Ph or C₈H₁₇, n = 1, 3a, 3b; R = Ph, n = 2, 3c), [(8-(Ph₂P(O)CH₂C(O)NR)(1,2-C₂B₉H₁₀))(1′,2′-C₂B₉H₁₁)-3,3′-Co]⁻ (R = H, C₂H₅, CH₂C₆H₅, 5a-c) and [(8-(²RPhP(O)CH₂C(O)N(¹R)CH₂-1,2-C₂B₉H₁₀))(8′-CH₃O-1′,2′-C₂B₉H₁₀)-3,3′-Co]⁻ (¹R = Benzyl, ²R = Ph or C₈H₁₇, 7a,b) were prepared with the aim to develop a new class of efficient extraction agents for partitioning of polyvalent f-block elements, i.e. lanthanides and actinides from high-level activity nuclear waste. The anionic ligands were characterized by multinuclear NMR spectroscopy and MS, the structures of Cs3a and the calcium complex of 7a were determined by X-ray diffraction analysis. The crystallographic study of the Cs3a proved a formation of linear chains in the structure, where the metal cation is coordinated by oxygen atoms of the CMPO terminal groups. The X-ray structure of the Ca²⁺ complex of the ionic ligand 7a proved a 1:3 metal to ligand ratio. Presented also is the X-ray structure of the starting ammonium compound 6 used in the synthesis of 7a and 7b. With exception of 5c, these anionic ligands are of high extraction efficiency, the highest being found for 7a in low polar solvent mixture hexyl methyl ketone-dodecane 1:1. These properties qualify some of these derivatives for possible technological applications.     

Chiral chelate phosphanes: XI. Application of cyclopentane-based C2 chiral bis(phosphane) ligands C5H8(PR2)2 to Pt---Sn-catalyzed styrene hydroformylation

Treatment of [(1,5-C₈H₁₂)PtCl(X)] (X=Cl, CH₃, CH₂CMe₃) with C₂ chiral cyclopentane-1,2-diyl-bis(phosphanes) C₅H₈(PR₂)₂, either as racemic mixtures or as resolved enantiomers, afforded the chelate complexes [C₅H₈(PR₂)₂Pt(Cl)(X)] (X=Cl: R=Ph (1), N-pip (2), OPh (3); X=CH₃: R=Ph (4), N-pip (5), OPh (6); X=CH₂CMe₃: R=Ph (7), N-pip (8), OPh (9); ‘N-pip’=N(CH₂)₅), (+)-[(1R,2R)-C₅H₈{P(OPh)₂}₂PtCl₂] [(R,R)-3], (−)-[(1S,2S)-C₅H₈{P(OPh)₂}₂PtCl₂] [(S,S)-3], (−)-[(1R,2R)-C₅H₈(PPh₂)₂Pt(Cl)(X)], and (+)-[(1S,2S)-C₅H₈(PPh₂)₂Pt(Cl)(X)] (X=CH₃: (R,R)-4, (S,S)-4; X=CH₂CMe₃: (R,R)-7, (S,S)-7). Reacting 4, 6, and 7 with AgO₃SCF₃ led to triflate derivatives [C₅H₈(PR₂)₂Pt(X)(OSO₂CF₃)] [X=CH₃: R=Ph (11), OPh (12); X=CH₂CMe₃: R=Ph (13)] with covalently bonded OSO₂CF₃ ligands. The unusual Pt₂ complex [μ-Cl{C₅H₈(PPh₂)₂PtCH₃}₂]O₃SCF₃ (14) containing an unsupported single Pt---Cl---Pt bridge was also isolated. In the presence of SnCl₂, complexes 1, 3, 4, 6, 7, and 9 are catalysts for the hydroformylation of styrene forming 2- and 3-phenylpropanal together with ethylbenzene. Except for 1, they also catalyze the consecutive hydrogenation of the primary propanals to alcohols. High regioselectivities towards 2-phenylpropanal (branched-to-normal ratios ≥91:9) were obtained in hydroformylations catalyzed by 3 and 4, for which the influence of varied CO/H₂ partial pressures, catalyst-to-substrate ratios and different reaction temperatures and times on the outcome of the catalytic reaction was also studied. When tin-modified complexes (R,R)-3, (S,S)-3, and (S,S)-4 were used as optically active Pt(II) catalysts, an only low stereoselectivity for asymmetric hydroformylation (e.e.<18%) was observed. The Pt---Sn complexes [C₅H₈(PR₂)₂Pt(CH₃)(SnCl₃)] [R=Ph (15), OPh (17)], resulting from SnCl₂ insertion into the Pt---Cl bonds of 4 or 6, undergo rapid degradation in solution, forming mixtures composed of [C₅H₈(PR₂)₂Pt(X)(Y)] with R=Ph or OPh and X/Y=Cl/SnCl₃ (16, 18), Cl/Cl (1, 3), and SnCl₃/SnCl₃ (19, 20), respectively. In the presence of SnCl₂, triflate complex 11 also becomes a catalyst for styrene hydroformylation and consecutive hydrogenation of the aldehydes to alcohols. The crystal structures of 11 complexes — 2, 5, 7, 8, 9, 10 (the previously prepared [C₅H₈{P(N-pip)₂}₂Pt(CH₂CMe₃)₂]), 13, 14, 16, (R,R)-3, and (S,S)-3 — were determined by X-ray diffraction.     

Massenspektrometrische Untersuchungen an Organophosphorverbindungen. II—Elektronenstoßinduzierte Fragmentierungen von Tetraorganodiphosphandisulfiden

The behaviour under electron impact (70 eV) which includes some rearrangement processes of some tetraorganodiphosphanedisulfides R₂P(S)-P(S)R₂ (R ? CH₃, C₂H₅, n-C₃H₇, n-C₄H₉, C₃H₅, C₆H₅) and CH₃RP(S)–P(S)CH₃R (R ? C₂H₅, n-C₃H₇, n-C₄H₉, C₆H₅, C₆H₅, C₆H₅,CH₂) is reported and discussed. Fragmentation patterns which are consistent with direct analysis of daughter ions and defocusing metastable spectra are given. The atomic composition of many of the fragment ions was determined by precise mass measurements. In contrast to compounds R₃P(S) loss of sulphur is not a common process here. The first step in the fragmentation of these compounds is cleavage of one P–C bond and loss of a substituent R?. The second step is elimination of RPS leading to [R₂PS]⁺ from which the base peaks in nearly all the spectra arise. The phenyl substituted compounds give spectra with very abundant [(C₆H₅)₃P]^+. and [(C₆H₅)₂CH₃P]^+. ions respectively, resulting from [M]^+. by migration of C₆H₅. Rearrangement of [M]^+. to a 4-membered P-S ring system prior to fragmentation is suggested.     

Reactions of nucleophilic addition of primary amines to the nitrilium derivative of the <Emphasis Type="Italic">closo</Emphasis>-decaborate anion [2-B<Subscript>10</Subscript>H<Subscript>9</Subscript>(N≡CCH<Subscript>3</Subscript>)]<Superscript>−</Superscript>

Compounds (Bu₄N)[2-B₁₀H₉{NH=C(NHR)CH₃}]⁻ are obtained by reactions of the tetrabutylammonium salt of the [2-B₁₀H₉(N≡CCH₃)]⁻ anion with aliphatic and aromatic primary amines RNH₂ (R = n-C₃H₇, n-C₄H₉, cyclo-C₅H₉, C₆H₅, cyclo-C₆H₁₁, n-C₆H₁₃, C₇H₇, C₈H₈NH₂, C₆H₄NO₂, and C₁₈H₃₇) and identified by IR, ESI/MS, and NMR (¹H, ¹¹B, and ¹³C) spectroscopy. The structures of the amidine-type derivatives [2-B₁₀H₉{Z-NH=C(NH-cyclo-C₅H₉)CH₃}]⁻ and [2-B₁₀H₉{Z-NH=C(NH-C₇H₇)CH₃}]⁻ are determined by X-ray diffraction.