Rational design and syntheses of 0-D, 1-D, and 2-D metal-organic frameworks (MOFs) from ferrocenedicarboxylate tetrametallic macrocyclic building units and subsidiary ligands

We have designed and synthesized three new metal-1,1′-ferrocenedicarboxylate complexes containing tetrametallic macrocyclic building units, namely, [Cd₂(η²-O₂CFcCO₂-η²)₂(phen)₂(H₂O)₂] · 4CH₃OH (1) (Fc = (η⁵-C₅H₄)Fe(C₅H₄-η⁵), phen = 1,10-phenanthroline), {[Cd(η²-O₂CFcCO₂)(pebbm)(H₂O)] · 2H₂O}_n (2) (pebbm = 1,1′-(1,5-pentanediyl)bis-1H-benzimidazole) and {[Cd(η²-O₂CFcCO₂-η²)(prbbm)(H₂O)] · 3H₂O}_n (3) (prbbm = 1,1′-(1,3-propanediyl)bis-1H-benzimidazole). Compound 1 is a 0-D discrete tetrametallic macrocyclic framework. Compound 2 features an infinite 1-D ribbon of rings structure constructed by the subsidiary ligands pebbm connecting tetrametallic macrocyclic building units. For 3, its tetrametallic macrocyclic building units are linked by the subsidiary ligands prbbm to form a 2-D network structure. The structural features of these complexes indicate that the ferrocenedicarboxylate tetrametallic macrocycle can be used as a successful molecular building unit and the shapes and conformational flexibility of subsidiary ligands play a crucial role in the manipulation of the configuration of the resultant MOFs. Their fluorescence spectra in solid state at room temperature suggest that the fluorescence emissions of 1-3 are ruled by 1,1′-ferrocenedicarboxylate ligand.     

Tetrametallic macrocyclic frameworks constructed from ferrocenedicarboxylato and 2,2-bipyridine: synthesis, molecular structures and characteristics

Four novel tetranuclear macrocyclic compounds [Cd₂(η²-O₂CFcCO₂)₂(2,2^′-bpy)₂(H₂O)₂] · 2H₂O (1), [Zn₂(η²-O₂CFcCO₂)₂(2,2^′-bpy)₂(H₂O)₂] · CH₃OH · H₂O (2), [Co₂(O₂CFcCO₂)₂(2,2^′-bpy)₂(μ₂-OH₂)₂] · CH₃OH · 2H₂O (3), and [Ni₂(O₂CFcCO₂)₂(2,2^′-bpy)₂(μ₂-OH₂)₂] · CH₃OH · 2H₂O (Fc=(η⁵-C₅H₄)Fe(η⁵-C₅H₄) (4) have been synthesized and structurally characterized by single crystal diffraction. The magnetic behaviors for compounds (3) and (4) are studied in the temperature range of 5.0-300 K. The results show that the antiferromagnetic coupling of Co^II-Co^II pairs occurs in (3), and unusual global ferromagnetic coupling between nickel (II) ions exists in (4). The solution-state differential pulse voltammetries of compounds (1)-(4) all show two peaks with large separations (ΔE) that indicate strong interactions between two ferrocene moieties. Their fluorescent and thermal properties were also investigated.     

Cationic olefin Pd(II) complexes bearing α-iminoketone N,O-ligands: synthesis, intramolecular and interionic characterization and reactivity with olefins and alkynes

Complexes [Pd(η¹, η²-5-OMe-C₈H₁₂)(N,O)]BF₄ (N,O=2,6-(i-Pr)₂(C₆H₃)NC(Ph)-C(Ph)O, 1; 2,6-(i-Pr)₂(C₆H₃)NC(Me)-C(Ph)O, 2; 2-benzoylpyridine, 3) were synthesized by the reactions of [Pd(η¹,η²-5-OMe-C₈H₁₂)Cl]₂ with the suitable N,O-ligand. They were tested as catalysts for olefin or alkyne polymerizations. During such reactions 1-3 quantitatively transformed into their η¹,η²-1-OMe-C₈H₁₂ isomers (1a-3a). The same isomerization occurred in methylene chloride, even in the absence of olefins or alkynes, with a much slower rate. All complexes were fully characterized in solution by multinuclear and multidimensional low temperature NMR spectroscopy. The solid state structures of complexes 1 and 1a were investigated by X-ray single crystal studies. ¹⁹F, ¹H-HOESY NMR experiments carried out in methylene chloride-d₂ at 217 K indicated that the anion prefers to locate on the side of N,O-ligand shifted toward the O-arm in 1-1a and 2-2a while it approaches the N-arm in 3 and 3a compounds.     

Amidoamine-based dendrimers with end-grafted Pd-Fe units: Synthesis, characterization and their use in the Heck reaction

The synthesis and characterization of novel amidoamine-based metallodendrimers with heterobimetallic end-grafted amidoferrocenyl-palladium-allyl chloride units is described. Dendrimer (Fe((η⁵-C₅H₄PPh₂)(η⁵-C₅H₄))C(O)HNCH₂CH₂NHC(O)CH₂CH₂)N[CH₂CH₂N(CH₂CH₂C(O)NHCH₂CH₂NH-C(O)(Fe(η⁵-C₅H₄)(η⁵-C₅H₄PPh₂)))₂]₂ (9-Fe) and the corresponding metal species (Fe((η⁵-C₅H₄PPh₂(Pd(η³-C₃H₅)Cl))(η⁵-C₅H₄))C(O)HNCH₂CH₂NHC(O)CH₂CH₂)N[CH₂CH₂N(CH₂CH₂C(O)NHCH₂CH₂NHC(O)(Fe(η⁵-C₅H₄)(η⁵-C₅H₄PPh₂(Pd(η³-C₃H₅)Cl))))₂]₂ (9-Fe-Pd) were prepared by a consecutive divergent synthesis methodology including addition-amidation cycles, standard peptide coupling, and coordination procedures. For comparative reasons also the monomeric and dimeric molecules (Fe(η⁵-C₅H₄PPh₂)(η⁵-C₅H₄C(O)NHⁿC₃H₇)) (5-Fe) and [Fe(η⁵-C₅H₄PPh₂)(η⁵-C₅H₄C(O)NHCH₂)]₂ (6-Fe) as well as N(CH₂CH₂C(O)NHCH₂CH₂NHC(O)(Fe(η⁵-C₅H₄)(η⁵-C₅H₄PPh₂)))₃ (7-Fe) and [CH₂N(CH₂CH₂C(O)NHCH₂CH₂NHC(O)(Fe(η⁵-C₅H₄)(η⁵-C₅H₄PPh₂)))₂]₂ (8-Fe) were prepared from Fe(η⁵-C₅H₄PPh₂)(η⁵-C₅H₄CO₂H) (3). Using [Pd(η³-C₃H₅)Cl]₂ (4) as palladium source heterobimetallic metallodendrimers (Fe(η⁵-C₅H₄PPh₂(Pd(η³-C₃H₅)Cl))(η⁵-C₅H₄C(O)NHⁿC₃H₇)) (5-Fe-Pd), [Fe(η⁵-C₅H₄PPh₂(Pd(η³-C₃H₅)Cl))(η⁵-C₅H₄C(O)NHCH₂)]₂ (6-Fe-Pd), N(CH₂CH₂C(O)NHCH₂CH₂NHC(O)(Fe(η⁵-C₅H₄)(η⁵-C₅H₄PPh₂(Pd(η³-C₃H₅)Cl))))₃ (7-Fe-Pd) and [CH₂N(CH₂CH₂C(O)NHCH₂CH₂NHC(O)(Fe(η⁵-C₅H₄)(η⁵-C₅H₄PPh₂(Pd(η³-C₃H₅)Cl))))₂]₂ (8-Fe-Pd) were synthesized. Additionally, seleno-phosphines of 5-Fe-Se and 9-Fe-Se, respectively, were prepared by addition of elemental selenium to 5-Fe or 9-Fe to estimate their σ-donor properties.The palladium-containing amidoamine supports are catalytically active in the Heck-Mizoroki cross-coupling of iodobenzene with tert-butyl acrylate. The catalytic data are compared to those obtained for the appropriate mononuclear and dinuclear compounds 5-Fe-Pd and 6-Fe-Pd. This comparison confirms a positive cooperative effect. The mercury drop test showed that (nano)particles were formed during catalysis, following on heterogeneous carbon-carbon cross-coupling.     

1-D Polymeric divalent metal m-ferrocenylbenzoates: Structures, NLO and electrochemical properties

Three 1-D metal-organic polymers containing m-ferrocenylbenzoate components: {[Pb(μ₂-η²-OOCH₄C₆Fc)₂] · (CH₃OH)₂}_n (1), [Zn(OOCH₄C₆Fc)₂(bpe)]_n (2) and [Mn(η²-OOCH₄C₆Fc)₂(4,4′-bpy)]_n (3) were synthesized and structurally characterized. In polymer 1, each m-FcC₆H₄COO⁻ anion adopts a tridentate fashion, bridging the central Pb(II) ions to form a 1-D chain. Polymers 2 and 3 give similar zigzag chain structures. Their third-order NLO properties were investigated with 532 nm laser pulses of 8 ns duration by Z-scan experiment in DMF solution. All of the polymers exhibit good NLO refractive properties with self-focusing behaviors. The third-order NLO refractive indexes n₂ are 2.44 × 10⁻¹¹ esu for 1, 2.33 × 10⁻¹¹ esu for 2, and 2.10 × 10⁻¹¹ esu for 3, respectively. Through quantum chemistry calculations, we conclude that the nonlinear refractive behaviors of the three polymers mainly come of the ferrocenyl units and organic adjuvant ligands; Mn(II) ions and Pb(II) ions have also some influence on NLO properties. The solution-state differential pulse voltammetrys indicate that the half-wave potential of the ferrocenyl moiety in 3 has slightly higher value than those of 1 and 2. This may be because the HOMO orbitals in 1 and 2 are located in the m-FcC₆H₄COO⁻ groups, while in 3 the HOMO orbital is located in the m-FcC₆H₄COO⁻ and Mn(II)groups, the charge transitions of the metal cores may play an important role in the change of the Fe(II)/Fe(III) oxidation potential of 3, so the Fe(II) centers of 1 and 2 are more easily oxidized to Fe(III) centers than that of 3.     

Palladium (II) complexes with mono-oxide 1,1′-bis(diphenylphosphino)metallocene ligands [Fe(η-C5Me4PPh2)(η-C5Me4P{O}Ph2)] and [Os(η-C5H4PPh2)(η-C5H4P{O}Ph2)]

The monoxides [Fe(η⁵-C₅Me₄PPh₂)(η⁵-C₅Me₄P{O}Ph₂)] (1) and [Os(η⁵-C₅H₄PPh₂)(η⁵-C₅H₄P{O}Ph₂)] (2) have been prepared by treatment of the corresponding diphosphines with CCl₄ and methanol.These ligands react with [Pd(PhCN)₂Cl₂] to give dichloride complexes of different structure.The dimeric complex [{Os(η⁵-C₅H₄PPh₂)(η⁵-C₅H₄P{O}Ph₂)}PdCl(μ-Cl)]₂ (4) contains the monodentate P-coordinated osmocene ligand with the free P{O}Ph₂ group, while the octamethylferrocene ligand gives the chelate k²-P,O complex [{Fe(η⁵-C₅Me₄PPh₂)(η⁵-C₅Me₄P{O}Ph₂)}PdCl₂] (3).The structures of 3 and 4 have been determined crystallographically.Treatment of 3 and 4 with silver salts in CH₂Cl₂ or acetonitrile leads to the corresponding dicationic complexes[{M(η⁵-C₅R₄PPh₂)(η⁵-C₅R₄P{O}Ph₂)}Pd(MeCN)_x]²⁺ (5, M = Fe, R = Me; 6, M = Os, R = H). Complex 5 decomposes upon isolation, in contrast 6 is rather stable, probably due to Os-Pd bonding. The dichlorides 3 and 4 catalyze catalytic amination of p-bromotoluene with N-(4-tolyl)morpholine with lower activity than (dppf)PdCl₂, however they perform comparable to (dppf)PdCl₂ activity in coupling of p-bromotoluene with p-methoxyphenyl boronic acid.     

m-Ferrocenylbenzoate-bridged lanthanide coordination polymers: Syntheses, structures, electrochemical and magnetic properties

A series of m-ferrocenylbenzoate [m-ferrocenylbenzoate = m-NaOOCH₄C₆Fc, Fc = (η⁵-C₅H₅)Fe(η⁵-C₅H₄)] lanthanide coordination polymers, namely [Ln(μ₂-OOCH₄C₆Fc)(η²-OOCH₄C₆Fc)(μ₂-η²-OOCH₄C₆Fc)(CH₃OH)₂]_n [Ln = La (1), Pr (2), Nd (3), Sm (4) and Gd (5)], have been synthesized by reactions of m-ferrocenylbenzoate with Ln(NO₃)₃·nH₂O. X-ray crystallographic analyses reveal that 1, 2 and 5 are essentially isostructural with unique one-dimensional linear chain structure. Three types of coordination modes for m-ferrocenylbenzoate are observed in the unit structure which consists of the eight-membered metallacycle Ln₂(COO)₂ and the rhomboid Ln₂O₂. Electrochemical studies indicate that 1-5 exhibit a reversible redox wave of Fe^II/Fe^III and the half-wave potentials of 1-5 are slightly more positive than that of m-ferrocenylbenzoic acid. Magnetic investigations show that an antiferromagnetic interaction between Gd(III) ions exists in 5.     

Synthesis, characterization and properties of some metal(II) 5-(nicotinamido)isophthalate complexes

Four new complexes, {[M(NAIP)(H₂O)₄]·2H₂O}_n (M = Co (1), M = Mn (2)), {[Zn(NAIP)]·0.5H₂O}_n (3) and {Cd(NAIP)(H₂O)₂]·1.5H₂O}_n (4) [H₂NAIP = 5-(nicotinamido)-isophthalic acid] have been prepared and structurally characterized. The ligand NAIP²⁻ exhibits different coordination modes and leads to the formation of various architectures. Complexes 1 and 2 show a one-dimensional (1D) zigzag chain, where hydrogen-bonding interactions further link these chains to a three dimensional (3D) supramolecular structure. For complex 3, a 3D coordination network with a four-coordinated Zn(II) and NAIP²⁻ as a SBU was observed. Complex 4 presents a three-connected 2-fold interpenetrated 3D network with a (10, 3)-b net topology. Their luminescent and magnetic properties have been investigated in the solid state.     

Hydrothermal synthesis, crystal structures and fluorescence properties of three novel frameworks constructed with mixed ligands of isophthalic acid (1,3-BDC) and 2,3-di-2-pyridylquinoxaline (Dpdq): [M(1,3-BDC)(Dpdq)(H2O)m] · nH2O (M = Co, Cd or Zn)

Three novel metal-organic frameworks [M(1,3-BDC)(Dpdq)(H₂O)_m] · nH₂O, (M = Co^II (1), Cd^II (2) or Zn^II (3); m = 0, 1; n = 0, 1, 2, respectively) have been obtained from hydrothermal reactions of three different metal(II) nitrates with the same mixed ligands [isophthalic acid (1,3-BDC) and 2,3-di-2-pyridylquinoxaline (Dpdq)], and structurally characterized by elemental analyses, IR spectroscopy, and single-crystal X-ray diffraction analyses. Single-crystal X-ray analyses show that each pair of metal ions are bridged by various coordination modes of 1,3-BDC ligands to form left- and right-handed helical chains in 1, linear chains in 2, and double chains in 3, respectively. N-containing flexible ligand Dpdq takes a chelating coordination mode acting as terminal ligand. In the compound 1, adjacent left- and right-handed helical chains are packed through hydrogen bonds to form a two-dimensional (2-D) structure. In the compounds 2 and 3, adjacent chains are further linked by hydrogen bonds and/or π-π stacking interactions to form a three-dimensional (3-D) distorted hexagon meshes supramolecular framework for 2 and a ZnS-related three-dimensional (3-D) topology for 3, respectively. The different structures of compounds 1-3 illustrate that the influence of the metal ions in the self-assembly of polymeric coordination architectures. In addition, compounds 2 and 3 exhibit blue emission in the solid state at room temperature.     

Synthesis and characterization of the cluster complexes containing tetrahedral FeCrCo(μ3-S) cluster cores generated by isolobal displacement reactions. Crystal structures of (η-RC5H4)FeCrCo(μ3-S)(CO)8 (R=H, CO2Et) and FeCo2(μ3-S)2(CO)9

The monoanions (η⁵-RC₅H₄)(CO)₃Cr⁻ (1, R=H; 2, R=Me; 3, R=CO₂Et) reacted with tetrahedral cluster FeCo₂(μ₃-S)(CO)₉ to give single isolobal displacement products (η⁵-RC₅H₄)FeCrCo(μ₃-S)(CO)₈ (4, R=H; 5, R=Me; 6, R=CO₂Et) in 86-89% yields, whereas monoanion (η⁵-RC₅H₄)(CO)₃Cr⁻ (7, R=C(O)Me) reacted with FeCo₂(μ₃-S)(CO)₉ to afford the expected single isolobal displacement product (η⁵-RC₅H₄)FeCrCo(μ₃-S)(CO)₈ (8, R=C(O)Me) in 5% yield and an unexpected square pyramidal cluster FeCo₂(μ₃-S)₂(CO)₉ (9) in 45% yield. Similarly, the dianions [η⁵-C₅H₄CH₂(CH₂OCH₂)_nCH₂C₅H₄-η⁵][(CO)₃Cr⁻]₂ (10, n=1; 11, n=2; 12, n=3) reacted with two molecules of FeCo₂(μ₃-S)(CO)₉ to produce double isolobal displacement products [η⁵-C₅H₄CH₂(CH₂OCH₂)_nCH₂C₅H₄-η⁵][FeCrCo(μ₃-S)(CO)₈]₂ (13, n=1; 14, n=2; 15, n=3) in 32-36% yields, while treatment of dianion [η⁵-C₅H₄C(O)CH₂]₂[(CO)₃Cr⁻]₂ (16) with two molecules of FeCo₂(μ₃-S)(CO)₉ gave the unexpected square pyramidal cluster FeCo₂(μ₃-S)₂(CO)₉ (9) in 42% yield and the corresponding double isolobal displacement product [η⁵-C₅H₄C(O)CH₂]₂[FeCrCo(μ₃-S)(CO)₈]₂ (17) in 8% yield. Products 4-6, 8, 9, 13-15 and 17 were characterized by elemental analyses, IR and ¹H NMR spectroscopy, as well as for 4, 6 and 9 by X-ray diffraction techniques.     

Synthesis and reactivity of [(η-[32](1,3)Cyclophane)Mn(CO)3][BF4]

The manganese cyclophane complex, [(η⁶-[3₂](1,3)cyclophane)Mn(CO)₃][BF₄] 2, was prepared by the reaction of [[3₂](1,3)cyclophane] 1 with Mn(CO)₅FBF₃. Reaction of 2 with NaBH₃CN yielded the cyclohexadienyl manganese complex [(η⁵-6H-[3₂](1,3)cyclophane)Mn(CO)₃] 3. Interestingly, treatment of 3 with Mn(CO)₅FBF₃ gave the bis-manganese complex (η⁶,η⁵-6H-[3₂](1,3)cyclophane)[Mn(CO)₃]₂[BF₄] 4. When NaBH₃CN was treated with 4, [(η⁵,η⁵-6H,6^′H-[3₂](1,3)cyclophane)Mn(CO)₃] 5 was isolated as yellow crystals. The structure of compounds 2 and 3 were determined by single-crystal X-ray crystallography.     

Synthesis, crystal structure and magnetic properties of three polynuclear manganese compounds bearing ferrocenecarboxylato ligands

The reactions of sodium ferrocenecarboxylate (FcCO₂Na) and Mn(ClO₄)₂ · 6H₂O in methanol in the presence of ancillary ligands of 1,10-phenanthroline (phen) or 2,2′-bipyridine (2,2′-bpy) produce three discrete polynuclear complexes bearing ferrocenecarboxylato ligands: [Mn₂(FcCO₂)₃(phen)₂](ClO₄) · 2CH₂Cl₂ (1), [Mn₃(FcCO₂)₆(2,2′-bpy)₂] · 2H₂O (2) and [Mn₄O₂(FcCO₂)₇(2,2′-bpy)₂]ClO₄ · 2CH₂Cl₂ · 6H₂O (3). It is shown that their composition and skeletons are tuned by the ancillary ligands and the ratios of starting materials. In dimanganese complex 1, both Mn(II) ions are pentacoordinated in a distorted trigonal bipyramidal geometry and bridged by three ferrocenecarboxylato ligands in a distorted syn-syn bridging mode, which is rare in triply carboxylato-bridged dimanganese complexes. Compound 2 presents a linear trinuclear [Mn₃(μ₂-η¹:η¹-O₂CFc)₄(μ₂-η¹:η²-O₂CFc)₂] core, in which six ferrocencarboxylato ligands show two different bridging modes. The cationic Mn₄O₂ core of 3 has a butterfly structure, in which two Mn(III) ions at “body” sites are bridged by an additional ferrocenecarboxylato ligand and they are further connected to the Mn(III) ions at “wing-tip” sites by ferrocenecarboxylato ligands. Magnetic susceptibilities of 1 and 2 were measured. Both of them mediate a weak antiferromagnetic coupling between the Mn(II) ions bridged by ferrocenecarboxylato ligands.     

Synthesis, characterization and crystal structures of a new 2-ferrocenylnaphthoxazole and its mercurated derivatives

A new ferrocenylnaphthoxazole [(η⁵-C₅H₅)Fe{(η⁵-C₅H₄)C(O)N(C₁₀H₆)}] (1) was synthesized under mild conditions. Two mercurated derivatives: ortho-mercurated product [HgCl{(η⁵-C₅H₅)Fe[(η⁵-C₅H₃)C(O)N(C₁₀H₆)]}] (2) and the product mercurated on the unsubstituted Cp ring [HgCl{(η⁵-C₅H₄)Fe[(η⁵-C₅H₄)C(O)N(C₁₀H₆)]}] (3) were obtained by the reaction of 1 with mercuric acetate. All the new compounds 1, 2 and 3 were characterized by elemental analyses, IR, NMR, MS spectra and X-ray crystal structure analysis. The crystal structure of 1 extended into a 2D supramolecular network through the intermolecular π-π stacking interaction between the Cp ring and naphthoxazole ring. In the crystal of 2, there exist bridged Cl-Hg bonds, CH(Cp) ? Cl and CH? Hg hydrogen bonds, π-π stacking interactions, which facilitate construction of this complex into a 3D supramolecular structure.     

Carbon-rich organometallic materials derived from 4-ethynylphenylferrocene

Using 4-ethynylphenylferrocene (1) as the building block, a new series of rigid-rod alkynylferrocenyl precursors consisting of fluoren-9-one unit, 2-bromo-7-(4-ferrocenylphenylethynyl)fluoren-9-one (2a), 2,7-bis(4-ferrocenylphenylethynyl)fluoren-9-one (2b), 2-trimethylsilylethynyl-7-(4-ferrocenylphenylethynyl)fluoren-9-one (3) and 2-ethynyl-7-(4-ferrocenylphenylethynyl)fluoren-9-one (4) have been prepared in moderate to good yields. The acetylene complex 4 is a useful precursor for the synthesis of well-defined carbon-rich ferrocenyl heterometallic complexes, trans-[(η⁵-C₅H₅)Fe(η⁵-C₅H₄)C₆H₄CCRCCPt(PEt₃)₂Ph] (5), trans-[(η⁵-C₅H₅)Fe(η⁵-C₅H₄)C₆H₄CCRCCPt(PBu₃)₂CCRC≡CC₆H₄(η⁵-C₅H₄)Fe(η⁵-C₅H₅)] (6), trans-[(η⁵-C₅H₅)Fe(η⁵-C₅H₄)C₆H₄CCRCCM(dppm)₂Cl] (M=Ru (7), Os (8)) (R=fluoren-9-one-2,7-diyl). All new complexes have been characterized by FTIR, NMR and UV-Vis spectroscopies and fast atom bombardment mass spectrometry (FABMS). The molecular structures of 1, 2a, 4, 6 and 8 have been determined by single-crystal X-ray studies where an ironiron through-space distance of nanosized dimension (ca. 42 Å) is observed in the trimetallic molecular rod 6. The electronic absorption, luminescence and electrochemical properties of these carbon-rich molecules were investigated and the data were correlated with the theoretical results obtained by the method of density functional theory.     

Synthesis and characterization of the first transition-metal fullerene complexes containing bis(η-benzene)chromium moieties

While photochemical reaction of C₆₀ with an equimolar amount of Mo(CO)₄(η⁶-Ph₂PC₆H₅)₂Cr (1) in toluene at room temperature produced bimetallic Mo/Cr fullerene complex fac/mer-(η²-C₆₀)Mo(CO)₃[(η⁶-Ph₂PC₆H₅)₂Cr] (2) in 87% yield, the thermal reaction of an equimolar mixture of C₆₀, M(dba)₂ (M = Pd, Pt; dba = dibenzylideneacetone) and (η⁶-Ph₂PC₆H₅)₂Cr (3) in toluene at room temperature afforded bimetallic M/Cr fullerene complexes (η²-C₆₀)M[(η⁶-Ph₂PC₆H₅)₂Cr] (4, M = Pd; 5, M = Pt) in 88% and 92% yields, respectively. Products 2, 4 and 5 are the first transition-metal fullerene complexes containing bis(η⁶-benzene)chromium moieties. While 2, 4 and 5 were characterized by elemental analysis and spectroscopy, the crystal molecular structures of 4 along with the starting materials 1 and 3 have been determined by X-ray diffraction techniques.     

Iridium(I) complex of chelating pyridine-2-thiolate ligand: Synthesis, reactivity, and application to the catalytic E-selective terminal alkyne dimerization via C-H activation

A novel iridium(I) complex bearing a chelate-coordinated pyridine-2-thiolate ligand [Ir(η²-SNC₅H₄)(PPh₃)₂] (2) was prepared by the reaction of iridium ethylene complex [IrCl(C₂H₄)(PPh₃)₂] (1) with lithium salt of pyridine-2-thiol (Li[SNC₅H₄]). On the treatment of iridium(I) complex 2 with chloroform, iridium(III) dichloro-complex [IrCl₂(η²-SNC₅H₄)(PPh₃)₂] (3) was formed. Reactions of complex 2 with methyldiphenylsilane, acetic acid, and p-tolylacetylene afforded iridium(III) hydride complexes [IrH(SiMePh₂)(η²-SNC₅H₄)(PPh₃)₂] (4), [IrH(O₂CCH₃)(η²-SNC₅H₄)(PPh₃)₂] (5), and [IrH(CC(p-tolyl))(η²-SNC₅H₄)(PPh₃)₂] (6), respectively. Complex 2 catalyzed dimerization of terminal alkynes leading to enynes (7) with high E-selectivity via C-H bond activation.     

Syntheses and structures of iron carbonyl complexes derived from N-(5-methyl-2-thienylmethylidene)-2-thiolethylamine and N-(6-methyl-2-pyridylmethylidene)-2-thiolethylamine

The reaction of N-(5-methyl-2-thienylmethylidene)-2-thiolethylamine (1) with Fe₂(CO)₉ in refluxing acetonitrile yielded di-(μ₃-thia)nonacarbonyltriiron (2), μ-[N-(5-methyl-2-thienylmethyl)-η¹:η¹(N);η¹:η¹(S)-2-thiolatoethylamido]hexacarbonyldiiron (3), and N-(5-methyl-2-thienylmethylidene)amine (4). If the reaction was carried out at 45 °C, di-μ-[N-(5-methyl-2-thienylmethylidene)-η¹(N);η¹(S)-2-thiolethylamino]-μ-carbonyl-tetracarbonyldiiron (5) and trace amount of 4 were obtained. Stirring 5 in refluxing acetonitrile led to the thermal decomposition of 5, and ligand 1 was recovered quantitatively. However, in the presence of excess amount of Fe₂(CO)₉ in refluxing acetonitrile, complex 5 was converted into 2-4. On the other hand, the reaction of N-(6-methyl-2-pyridylmethylidene)-2-thiolethylamine (6) with Fe₂(CO)₉ in refluxing acetonitrile produced 2, μ-[N-(6-methyl-2-pyridylmethyl)-η¹ (N_py);η¹:η¹(N); η¹:η¹(S)-2-thiolatoethylamido]pentacarbonyldiiron (7), and μ-[N-(6-methyl-2-pyridylmethylidene)-η²(C,N);η¹:η¹(S)-2- thiolethylamino]hexacarbonyldiiron (8). Reactions of both complex 7 and 8 with NOBF₄ gave μ-[(6-methyl-2-pyridylmethyl)-η¹(N_py);η¹:η¹(N);η¹:η¹(S)-2-thiolatoethylamido](acetonitrile)tricarbonylnitrosyldiiron (9). These reaction products were well characterized spectrally. The molecular structures of complexes 3, 7-9 have been determined by means of X-ray diffraction. Intramolecular 1,5-hydrogen shift from the thiol to the methine carbon was observed in complexes 3, 7, and 9.     

1-Methylimidazolin-2-yl functionalized cyclopentadienyl complexes of titanium and zirconium. Crystal structure of {[η:η-κN-C5H4CPh2CH2-(1-Me-C3H4N2)]ZrCl2}2(μ-Cl)2

The novel bidentate ligand, C₅H₄CPh₂CH₂-(1-Me-C₃H₄N₂) (3), has been prepared and characterized as its lithium salt LiC₅H₄CPh₂CH₂-(1-Me-C₃H₄N₂) (3-Li). Cyclopentadiene HC₅H₄CPh₂CH₂-(1-Me-C₃H₄N₂) (3-H) has been obtained from 6,6-diphenylfulvene and 1,2-dimethylimidazoline (1). In THF-d₈ solution in the presence of 1, (1-methylimidazoline-2-yl)methyllithium (2) has been proved to undergo gradual conversion into a dilithium derivative of N¹-methyl-N²-[(1E,2E)-1-methyl-2-(1-methylimidazolidine-2-idene)ethylidene]ethane-1,2-diamine (2a). In a solution, cyclopentadiene 3-H has been shown to undergo isomerization into 3-{N-[2-(N-methylamino)ethyl]amino}-1,1-diphenyl-1,2-dihydropentalene (4) and, further, into a mixture of 4 and two rotameric 3-[N-(2-aminoethyl)-N-methylamino]-1,1-diphenyl-1,2-dihydropentalenes (5a) and (5b). Treatment of the lithium salt 3-Li with Me₃SiCl has lead to 3-{N-[2-(N-trimethylsilylamino)ethyl]amino}-1,1-diphenyl-1,2-dihydropentalene (6) as the dominant component in the reaction mixture. In the latter case the expected Me₃Si-C₅H₄CPh₂CH₂-(1-Me-C₃H₄N₂) (3-Si) was not observed. Stannylation of 3-Li with 1 equiv. of Me₃SnCl has resulted in formation of a mixture of Me₃Sn-C₅H₄CPh₂CH₂-(1-Me-C₃H₄N₂) (3-Sn), (Me₃Sn)₂-C₅H₃CPh₂CH₂-(1-Me-C₃H₄N₂) (3-Sn₂), and cyclopentadiene 3-H in a ca. 2:1:1 molar ratio. Monocyclopentadienyl complexes {[η⁵:η¹-κN-C₅H₄CPh₂CH₂-(1-Me-C₃H₄N₂)]MCl₃ (M = Ti (7), Zr (8)) have been prepared starting from the organotin and organolithium compounds 3-Sn and 3-Li, respectively. The dynamic behavior of complexes 7 and 8 has been investigated by means of variable-temperature NMR spectroscopy in solutions. The molecular structures of the dihydropentalene 4, binuclear complex {[η⁵:η¹-κN-C₅H₄CPh₂CH₂-(1-Me-C₃H₄N₂)]ZrCl₂}₂(μ-Cl)₂8, and a coordination dimer of the dilithium salt 2a have been established by X-ray diffraction analysis. In the crystal structure of the 2a-dimer, the shortest known Li-Li contact has been found.     

The effect that 6-tert-butoxyhexyl functionalization has on ethylene polymerization in ansa-zirconocene dichlorides

Ethylene polymerization studies have been carried out with novel precatalysts of the type: [(η⁵-C₁₃H₈)-X(t-BuOC₆H₁₂)Me-(η⁵-C₅H₄)]ZrCl₂ [X=C [1a], Si [2a]], [(η⁵-C₁₃H₈)-XMe₂-(η⁵-(t-BuOC₆H₁₂C₅H₃))] ZrCl₂ [X=C [3a], Si [4a]] in the presence of excess methylalumoxane (MAO) to compare their catalytic activity and to delineate the effect of the 6-t-butoxyhexyl functionality on ethylene polymerization. The precatalysts [1a] and [2a] with the bridge functionality showed higher activity in ethylene polymerization than the corresponding complexes [3a] and [4a] which have it on the Cp ring moiety. On the other hand the silyl bridged complexes [2a] and [4a] produced a higher molecular weight polyethylene than the carbon-bridged one, regardless of the location of functional group.     

Formation of ferraboranes from pentaborane(9) or BH3 · thf and an electron-rich cyclopentadienyl iron phosphine hydride

[(η⁵-C₅R₅)Fe(PMe₃)₂H] (R = H, Me) can be made in good yields in a simple one-pot reaction between FeCl₂, PMe₃, C₅R₅H (R = H, Me) and Na/Hg in thf. Reaction of [(η⁵-C₅H₅)Fe(PMe₃)₂H] with pentaborane(9) gives the known metallaborane [(η⁵-C₅H₅)-nido-2-FeB₅H₁₀] (1) in improved yield as well as the new metallaboranes [(η-C₅H₅)-nido-2-FeB₅H₈{μ-5,6-Fe(η⁵-C₅H₅)(PMe₃)(μ-6,7-H)}] (2), [(η-C₅H₅)(PMe₃)-arachno-2-FeB₃H₈] (3), [(η⁵-C₅H₅)₂-capped-nido-2,3-Fe₂B₄H₈] (4), [(η⁵-C₅H₅)-nido-2-FeB₄H₇(PMe₃)] (5) and [(η⁵-C₅H₅)-nido-2-FeB₅H₈(PMe₃)] (6). Reaction of [(η⁵-C₅Me₅)Fe(PMe₃)₂H] with pentaborane(9) gives predominantly [(η⁵-C₅Me₅)-nido-2-FeB₅H₁₀] (7) and [(η⁵-C₅Me₅)(PMe₃)-arachno-2-FeB₃H₈] (8). Reaction of [(η⁵-C₅H₅)Fe(PMe₃)₂H] with 2 equiv. of BH₃ · thf gives low yields of ferrocene and compound 3. Compound 7 thermally isomerises to the apical isomer [(η⁵-C₅H₅)-nido-2-FeB₅H₁₀] (9) in low yield. Compounds 1 and 7 deprotonate cleanly in the presence of KH at the unique B-H-B bridge to give [(η⁵-C₅H₅)-nido-2-FeB₅H₉⁻][K⁺] (10) and [(η⁵-C₅Me₅)-nido-2-FeB₅H₉⁻][K⁺] (11) respectively, whilst 6 deprotonates more slowly at one of two equivalent B-H-B bridges to give the fluxional anion [(η⁵-C₅H₅)-nido-2-FeB₅H₇(PMe₃)⁻] (12).