Complexation and C-H bond activation of 1,5-cyclooctadiene on triosmium carbonyl clusters

Reaction of Os₃(CO)₁₀(NCMe)₂ and 1,5-cyclooctadiene (C₈H₁₂) affords the diene complex Os₃(CO)₁₀(η⁴-C₈H₁₂) (1) with the two alkene moieties coordinated to an equatorial and an axial positions of one osmium atom. Thermolysis of 1 in refluxing n-hexane results in a vinylic C-H bond activation to form (μ-H)Os₃(CO)₉(μ,η⁴-C₈H₁₁) (2) in good isolated yield. The crystal structures of 1 and 2 have been established by an X-ray diffraction study.     

Synthesis of Mo(CO)2(η-PPh2(o-C6H4)C(O)H)2 and its reaction with C60

Reaction of Mo(CO)₃(NCMe)₃ and PPh₂(o-C₆H₄)C(O)H (abbreviated as PCHO) at room temperature affords Mo(CO)₂(η³-PCHO)₂ (1), while compound 1 and the phosphine-imine complex Mo(CO)₄(η²-PPh₂(o-C₆H₄)CHNMe) (2) are obtained by using Mo(CO)₃(η³-(MeNCH₂)₃) as the reactant. Thermal reaction of 1 with C₆₀ products Mo(CO)₂(η⁴-(PPh₂(o-C₆H₄)CH)₂)(η²-C₆₀) (3) in low yield, apparently through coupling of the formyl moieties. The structures of 1 and 3 have been determined by an X-ray diffraction study. The two aldehyde groups of 1 and C₆₀ ligand of 3 are coordinated to the molybdenum atom in a π-fashion.     

Cyclorhenated compounds derived from 1,4-diaryl-1-azabutadienes: preparation, structures and reactions

PhCH₂Re(CO)₅ reacted with 1,4-diaryl-1-azabutadienes to give cyclometallated (η²-(C,N)-azabutadiene)Re(CO)₄ (4) together with the substituted derivatives (η¹-(N)-azabutadiene)(η²-(C,N)-azabutadiene)Re(CO)₃ (6 and 7) The substituted product was shown by NMR and X-ray crystal structure analysis to be an inseparable mixture of isomers differing in the conformation of the η¹-ligand about the NC bond—trans for (6) and cis for (7). Reaction of the mixture of 6 and 7 from 1,4-diphenyl-1-azabutadiene with phenyl acetylene gave η⁵-(1,2,4-triphenyl-1-aza-cyclohexadienyl)Re(CO)₃.     

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.     

Arenechromiumtricarbonyl complexes of silyl(germyl)(stannyl)- and silyl(germyl)(plumbyl)methanes including the unexpected formation of arenechromiumtricarbonyldimethylsilanol, (η-C6H5)Cr(CO)3SiMe2OH

Treatment of PhMe₂SiCH₂GeMe₃ (1) with t-BuLi followed by addition of Me₃ECl, E = Sn, Pb, results in the formation of phenylsilyl(germyl)stannyl- and phenylsilyl(germyl)plumbyl-methanes, PhMe₂Si(Me₃Ge)(EMe₃)CH, E = Sn (2), Pb (3). The thermal reaction of 1, 2 and 3 with Cr(CO)₆ yields the corresponding aryl-Cr(CO)₃ analogs, {(η⁶-C₆H₅)Cr(CO)₃}Me₂Si(Me₃Ge)CH₂ (4) and {(η⁶-C₆H₅)Cr(CO)₃}Me₂Si(Me₃Ge)(EMe₃)CH, E = Sn (5), Pb (6). The thermal treatment of 2 with Cr(CO)₆ in a wet THF/di-n-butyl ether mixture results in the formation of the arenechromiumtricarbonyl silanol {(η⁶-C₆H₅)Cr(CO)₃}Me₂SiOH (7) which exhibits amphiphilic character, forming H-bonded chains in the solid state in a head-to-head arrangement of the areneCr(CO)₃ units.     

Reactivity of [CpCr(CO)3]2 towards thione (CS) moieties in some sulfur-containing substrates

The reaction of [CpCr(CO)₃]₂ (Cp = η⁵-C₅H₅) (1) with 1 mol equivalent of 2,5-dimercapto-1,3,4-thiadiazole (DMcTH₂) at ambient temperature led to the isolation of a reddish-brown crystalline solid of CpCr(CO)₃(η¹-DMcTH) (5) and a green solid of CpCr(CO)₃H (2) in yields of ca. 28% and 30%, respectively, along with some [CpCr(CO)₂]₂ (3) and [CpCr(CO)₂]₂S (4). The reaction of 1 with 1 mol equivalent of vinylene trithiocarbonate (SCS(CH)₂S) (VTTC) at 90 °C led to the isolation of a red crystalline solid of CpCr(CO)₂(η²-SCHSC₂H₂) (6) in ca. 15% yield while the reaction of 1 with isopropylxanthic disulfide ((CH₃)₂CHOCS₂)₂ resulted in the formation of CpCr(CO)₂(η²-S₂COCH(CH₃)₂) (8) in ca. 80% yield. The complexes 5, 6 and 8 have been determined by single crystal X-ray diffraction analysis.     

Synthetic, X-ray structural and protonation studies of CpCr(CO)2SPy and CpCr(CO)2SPym (SPy = C5H4NS, SPym = C4H3N2S)

The facile reaction of [CpCr(CO)₃]₂ (Cp = η⁵-C₅H₅) (1) with one mole equivalent of 2,2′-dithiodipyridine ((C₅H₄NS)₂(SPy)₂) at ambient temperature led to the isolation of dark brown crystalline solids of CpCr(CO)₂(η²-SPy) (2) in ca. 72% yield. 2 undergoes quantitative conversion to CpCrCl₂(η¹-SPyH) (3) with HCl. The reaction 1 with one mole equivalent of 2-mercaptopyrimidine (C₄H₃N₂SHHSPym) at ambient temperature led to the isolation of reddish-brown crystalline solids of CpCr(CO)₂(η²-SPym) (4) and green solids of CpCr(CO)₃H (5) in yields of ca. 42% and 46%, respectively. Reaction of 4 with HCl and subsequent workup in acetonitrile resulted in the cleavage of the thiolate ligand, giving the 15-electron chromium(III) species CpCrCl₂(CH₃CN) (6) and free 2-mercaptopyrimidine. The complexes 2-4 have been determined by single X-ray diffraction analysis.     

Synthesis and molecular structure of [Re2(μ:η-C24H18N4)(CO)6] containing the rtct-tetrakis(2-pyridyl)cyclobutandiyl ligand, derived from the reaction of [Re2(CO)8(MeCN)2] and 1,2-bis(2-pyridyl)ethene

The reaction of the labile compound [Re₂(CO)₈(CH₃CN)₂] with trans-1,2-bis(2-pyridyl)ethene (C₁₂H₁₀N₂) at room temperature in tetrahydrofuran affords the compounds [Re₂(μ:η³-C₁₂H₁₀N₂)(CO)₈] (1) and the oxidative addition product [Re₂(μ-H)(μ:η³-C₁₂H₉N₂)(CO)₇] (2). When the reaction is carried out at temperatures of refluxing tetrahydrofuran, besides compounds 1 and 2, the oxidative addition product [Re₂(μ-H)(μ:η⁴-C₁₂H₉N₂)(CO)₆] (3), the insertion product [Re₂(μ:η⁴-C₁₂H₁₀N₂)(CO)₈] (4) and [Re₂(μ:η⁶-C₂₄H₁₈N₄)(CO)₆] (5) are obtained. Compound 5 contains the organic ligand rtct-tetrakis(2-pyridyl)cyclobutandiyl which is derived from a [2 + 2] cycloaddition of 1,2-bis(2-pyridyl)ethene mediated by its coordination to the bimetallic framework. The molecular structures of 1, 2, 4 and 5 were confirmed by X-ray crystallographic studies.     

W(η-PhCCPh)3(η-Ph2PCCPPh2) as a ligand to prepare homo- and hetero-nuclear cluster complexes

Reaction of W(η²-PhCCPh)₃(NMe₃) (1) and Ph₂PCCPPh₂ (dppa) produces W(η²-PhCCPh)₃(η¹-Ph₂PCCPPh₂) (2), which contains a pendant phosphine group. Treatment of 2 with W(CO)₄(NCMe)₂ yields [W(η²-PhCCPh)₃](μ,η²-Ph₂PCCPPh₂)[W(CO)₄(NCMe)] (3). Compound 2 reacts with Os₃(CO)₁₀(NCMe)₂ to afford Os₃(CO)₁₀[(μ,η²-Ph₂PCCPPh₂)W(η²-PhCCPh)₃]₂ (4), and reacts with Ru₃(CO)₉(NCMe)₃ to afford Ru₃(CO)₉[(μ,η²-Ph₂PCCPPh₂)W(η²-PhCCPh)₃]₃ (5). The crystal structures of 2 and 3 are determined by an X-ray diffraction study.     

Alkynyl Ti-M complexes based on M(CO)4 and MO2 building blocks (M = Mo, W)

The synthesis and properties of heterobimetallic Ti-M complexes of type {[[Ti](μ-η¹:η²-CCSiMe₃)][M(μ-η¹:η²-CCSiMe₃)(CO)₄]} (M = Mo: 5, [Ti] = (η⁵-C₅H₅)₂Ti; 6, [Ti] = (η⁵-C₅H₄SiMe₃)₂Ti; M = W: 7, [Ti] = (η⁵-C₅H₅)₂Ti; 8, [Ti] = (η⁵-C₅H₄SiMe₃)₂Ti) and {[Ti](μ-η¹:η²-CCSiMe₃)₂}MO₂ (M = Mo: 13, [Ti] = (η⁵-C₅H₅)₂Ti; 14, [Ti] = (η⁵-C₅H₄SiMe₃)₂Ti). M = W: 15, [Ti] = (η⁵-C₅H₅)₂Ti; 16, [Ti] = (η⁵-C₅H₄SiMe₃)₂Ti) are reported. Compounds 5-8 were accessible by treatment of [Ti](CCSiMe₃)₂ (1, [Ti] = (η⁵-C₅H₅)₂Ti; 2, [Ti] = (η⁵-C₅H₄SiMe₃)₂Ti) with [M(CO)₅(thf)] (3, M = Mo; 4, M = W) or [M(CO)₄(nbd)] (9, M = Mo; 10, M = W; nbd = bicyclo[2.2.1]hepta-2,5-diene), while 13-16 could be obtained either by the subsequent reaction of 1 and 2 with [M(CO)₃(MeCN)₃] (11, M = Mo; 12, M = W) and oxygen, or directly by oxidation of 5-8 with air. A mechanism for the formation of 5-8 is postulated based on the in-situ generation of [Ti](CCSiMe₃)((η²-CCSiMe₃)M(CO)₅), {[Ti](μ-η¹:η²-CCSiMe₃)₂}-M(CO)₄, and [Ti](μ-η¹:η²-CCSiMe₃)((μ-CCSiMe₃)M(CO)₄) as a result of the chelating effect exerted by the bis(alkynyl) titanocene fragment and the steric constraints imposed by the M(CO)₄ entity.The molecular structure of 5 in the solid state were determined by single crystal X-ray diffraction analysis. In doubly alkynyl-bridged 5 the alkynides are bridging the metals Ti and Mo as a σ-donor to one metal and as a π-donor to the other with the [Ti](CCSiMe₃)₂Mo core being planar.     

Reactions of (Me2C)(Me2Si)[(η-C5H3)Mo(CO)3]2 with nitrile and subsequent cleavage of the CN bond by cooperation of molybdenum and ruthenium

Reaction of the doubly bridged dinuclear molybdenum complex (Me₂C)(Me₂Si)[(η⁵-C₅H₃)Mo(CO)₃]₂ (1) with benzonitrile in refluxing xylene afforded complexes (Me₂C)(Me₂Si)[(η⁵-C₅H₃)₂Mo₂(CO)₄(μ-η²-η²(⊥)-NCPh)] (2) (50%) and (Me₂C)(Me₂Si)[(η⁵-C₅H₃)₂Mo₂(CO)₄(μ-η¹-η²-NCPh)] (3) (6%) with different coordination of nitrile. The corresponding μ-η²-η² acetonitrile and propionitrile complexes 4 and 5 could be obtained from the reactions of (Me₂C)(Me₂Si)(C₅H₄)₂ with (RCN)₃Mo(CO)₃ (R = Me, Et) in refluxing xylene. Reactions of 1 with isonitriles generated μ-η¹-η²-CNR (R = ^tBu, Ph, C₆H₁₁) bridged complexes 6-8 in 53-63% yields. Subsequent reaction of 4 with Ru₃(CO)₁₂ yielded two CN bond cleavaged MoRu clusters (Me₂C)(Me₂Si)(η⁵-C₅H₃)₂Mo₂Ru₃(CO)₁₀(μ-CO)(μ₃-CMe)(μ₄-N) (9) (7%) and [(Me₂C)(Me₂Si)(η⁵-C₅H₃)₂]₂Mo₄Ru₆(CO)₁₆(μ-CO)(μ₄-CO)₂(μ₃-η¹-η²-η²-NCMe)(μ₃-CMe)(μ₅-N) (10) (8%). All the new complexes have been fully characterized. The molecular structures of 2, 4, 6, 9, and 10 have been determined by X-ray diffraction analysis.     

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.     

Reactivity of electron-poor decamethyl-1,3-diboraruthenocene with sulfur and phosphorus compounds

Decamethyl-1,3-diboraruthenocene [(η⁵-C₅Me₅)Ru{η⁵-(CMe)₃(BMe)₂}] (1) reacts with cyclo-octasulfur in hexane to give [(η⁵-C₅Me₅){η⁵-(CMe)₃(BMe)₂}RuS] (3), which may also be obtained from 1 and propylene sulfide. 1 reacts with H₂S to form the ruthenathiacarboranyl complex [(η⁵-C₅Me₅)Ru{η⁴-(CMe)₃(BMe)₂S}] (6), for which a nido-structure is proposed. The isomeric compounds 3 and 6 have different stabilities: 3 loses sulfur and unexpectedly the closo-cluster [(η⁵-C₅Me₅)₂Ru₂H(CMe)₃(BMe)₂] (4) is formed with hydrogen bridging the basal and apical Ru centers. Reaction of 1 with carbonylsulfide (COS) yields the dinuclear ruthenium compound [(η⁵-C₅Me₅)Ru{η⁵-(CMe)₃(BMe)₂(S)(COBMe)}]₂ (7) in which two B-O groups bridge two ruthenium complexes. Its formation results from a complex reaction sequence: sulfur inserts into the diborolyl ring and the ligand CO forms an oxygen-boron bridge to a second molecule, followed by insertion of the carbonyl carbon into the double bond of the diboraheterocycle. Carbon disulfide reacts with 1 to give the dinuclear complex 8 with two CS₂ molecules connecting the ruthenium centers. When 1 and P₄ are heated in toluene, the sandwich 9 is obtained by formal insertion of a P-H group into the diborolyl ring of 1 and the triple-decker [{η⁵-(C₅Me₅)Ru}₂{μ-(MeC)₃P(MeB)₂} (10) is detected in the mass spectrum. The phosphaalkyne PCtBu inserts into 1 to give the ruthenaphosphacarborane [(η⁵-C₅Me₅)Ru{(CMe)₂(BMe)(PCtBu)(CMe)(BMe)}] (11) in high yield. Phosphanes react with 1 to give weak donor-acceptor complexes 1 · PH₂R (12) (R=Ph, H). The compositions of the compounds are deduced from spectroscopic and analytical data and are confirmed for 4 and 7 by X-ray structural analyses.     

Ethynylferrocene insertion into Fe-C bond in bridging aminocarbyne diiron complexes: New triiron vinyliminium complexes

The μ-aminocarbyne complexes [Fe₂{μ-CN(Me)(R)}(μ-CO)(CO)(NCMe)(Cp)₂][SO₃CF₃] (R = Me, 1a; Xyl, 1b; Xyl = 2,6-Me₂C₆H₃) react with ethynylferrocene to give the corresponding bridging vinyliminium complexes [Fe₂{μ-η¹:η³-CN(Me)(R)CHC(Fc)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (R = Me, 2a; R = Xyl, 2b). Insertion of the ethynylferrocene in the metal-carbyne bond is regiospecific, and leads to the formation of only one isomer.Complexes 2a and 2b undergo hydride addition (by NaBH₄) affording the enaminoalkylidene complex [Fe₂{μ-η¹:η³-C(H)(N(Me)₂)CHC(Fc)}(μ-CO)(CO)(Cp)₂] (3a) and the bis-alkylidene [Fe₂{μ-η¹:η²-C(N(Me)(Xyl))CH₂C(Fc)}(μ-CO)(CO)(Cp)₂] (3b), respectively. Upon treatment with NaH, compounds 2a and 2b undergo fragmentation, affording the 1-metalla-2-aminocyclopenta-1,3-dien-5-one complexes [Fe(CO)(Cp){C(N(Me)(R))}CHC(Fc)C(O)}] (R = Me, 4a; R = Xyl, 4b).The molecular structures of 2b, 3b and 4b have been determined by X-ray diffraction studies.     

Os(CO)2(η-SC5H4N(O))(η-SC5H4N): structural evidence for the transformation of pyridine-2-thione N-oxide to pyridine-2-thiolate in osmium complexes

The reaction of Os₃(CO)₁₂ with an excess of 1-hydroxypyridine-2-thione and Me₃NO gives three mononuclear osmium complexes Os(CO)₂(η²-SC₅H₄N(O))₂ (1), Os(CO)₂(η²-SC₅H₄N(O))(η²-SC₅H₄N) (2), and Os(CO)₂(η²-SC₅H₄N)₂ (3). The results of single-crystal X-ray analyses reveal that complex 1 contains two O,S-chelate pyridine-2-thione N-oxide (PyOS) ligands, whereas complex 2 contains one O,S-chelate PyOS and one N,S-chelate pyridine-2-thiolate group. The unique structure of 2 provides evidence of the pathway for this transformation. When this reaction was monitored by ¹H NMR spectroscopy the triosmium complexes Os₃(CO)₁₀(μ-H)(μ-η¹-S-C₅H₄N(O)) (4) and Os₃(CO)₉(μ-H)(μ-η¹:η²-SC₅H₄N(O)) (5) were identified as intermediates in the formation of the mononuclear final products 1-3. The proposed pathway is further supported by the observation of several dinuclear osmium intermediates by electrospray ionization mass spectrometry. In addition, the reaction of Os₃(CO)₁₂ with 1-hydroxypyridine-2-thione in the absence of Me₃NO at 90 °C generated mononuclear complex 2 as the major product along with smaller amounts of complexes 1 and 3. These results suggest that the N-oxide facilitates the decarbonylation reaction. Crystal data for 1: monoclinic, space group C2/c, a = 26.9990(5) Å, b = 7.6230(7) Å, c = 14.2980(13) Å, β = 101.620(2)°, V = 2882.4(4) ų, Z = 8. Crystal data for 2: monoclinic, space group C2/c, a = 5.7884(3) Å, b = 13.9667(7) Å, c = 17.2575(9) Å, β = 96.686(1)°, V = 1385.69(12) ų, Z = 4.     

The activation and transformations of acenaphthylene by osmium carbonyl cluster complexes

The reaction of Os₃(CO)₁₀(NCMe)₂ (1) with an excess of acenaphthylene at room temperature provided the complex Os₃(CO)₁₀(μ-H)(μ-η²-C₁₂H₇) (2). Compound 2 contains a σ-π coordinated acenaphthyl ligand bridging an edge of the cluster. Compound 2 was converted to the complex Os₃(CO)₉(μ-H)₂(μ₃-η²-C₁₂H₆) (3) when heated to reflux in a cyclohexane solution. Compound 3 contains a triply bridging acenaphthyne ligand. Compound 3 reacts with acenaphthylene again at 160 °C to yield four new cluster complexes: Os₄(CO)₁₂(μ₄-η²:η²-C₁₂H₆) (4); Os₂(CO)₆(μ-η⁴-C₂₄H₁₂) (5); Os₃(CO)₉(μ-H)(μ₃-η⁴-C₂₄H₁₃) (6); and Os₂(CO)₅(μ-η⁴-C₂₄H₁₂)(η²-C₁₂H₈) (7). All compounds were characterized crystallographically. Compound 4 is a butterfly cluster of four osmium atoms bridged by a single acenaphthyne ligand. Compounds 5 and 7 are dinuclear osmium clusters containing metallacycles formed by the coupling of two equivalents of acenaphthyne. Compound 6 is a triosmium cluster formed by the coupling of an acenaphthyne ligand to an acenapthyl group that is coordinated to the cluster through a combination of σ and π-bonding.     

Mono and dinuclear half-sandwich platinum group metal complexes bearing pyrazolyl-pyrimidine ligands: Syntheses and structural studies

Reactions of 0.5 eq. of the dinuclear complexes [(η⁶-arene)Ru(μ-Cl)Cl]₂ (arene = η⁶-C₆H₆, η⁶-p-ⁱPrC₆H₄Me) and [(Cp∗)M(μ-Cl)Cl]₂ (M = Rh, Ir; Cp∗ = η⁵-C₅Me₅) with 4,6-disubstituted pyrazolyl-pyrimidine ligands (L) viz. 4,6-bis(pyrazolyl)pyrimidine (L1), 4,6-bis(3-methyl-pyrazolyl)pyrimidine (L2), 4,6-bis(3,5-dimethyl-pyrazolyl)pyrimidine (L3) lead to the formation of the cationic mononuclear complexes [(η⁶-C₆H₆)Ru(L)Cl]⁺ (L = L1, 1; L2, 2; L3, 3), [(η⁶-p-ⁱPrC₆H₄Me)Ru(L)Cl]⁺ (L = L1, 4; L2, 5; L3, 6), [(Cp∗)Rh(L)Cl]⁺ (L = L1, 7; L2, 8; L3, 9) and [(Cp∗)Ir(L)Cl]⁺ (L = L1, 10; L2, 11; L3, 12), while reactions with 1.0 eq. of the dinuclear complexes [(η⁶-arene)Ru(μ-Cl)Cl]₂ and [(Cp∗)M(μ-Cl)Cl]₂ give rise to the dicationic dinuclear complexes [{(η⁶-C₆H₆)RuCl}₂(L)]²⁺ (L = L1, 13; L2, 14; L3, 15), [{(η⁶-p-ⁱPrC₆H₄Me)RuCl}₂(L)]²⁺ (L = L1, 16; L2, 17; L3, 18), [{(Cp∗)RhCl}₂(L)]²⁺ (L = L1, 19; L2, 20; L3, 21) and [{(Cp∗)IrCl}₂(L)]²⁺ (L = L1 22; L2, 23; L3 24). The molecular structures of [3]PF₆, [6]PF₆, [7]PF₆ and [18](PF₆)₂ have been established by single crystal X-ray structure analysis.     

Transition metal cyclopentadienyl complexes bearing perfluoro-4-tolyl substituents

Depending on the ratio of starting materials and the reaction conditions, perfluorotoluene (C₆F₅CF₃) reacts with sodium cyclopentadienide (NaCp; Cp = C₅H₅) and excess sodium hydride to afford, after acidic aqueous workup, moderate to high yields of mono-, bis-, tris-, and tetrakis(perfluoro-4-tolyl)cyclopentadiene (1, 2, 3, and 4, respectively). Treatment of 1 with excess NaH in THF afforded sodium (perfluoro-4-tolyl)cyclopentadienide (5) in 90% yield. Reaction of FeBr₂ with 2 equiv. of 5 afforded a 68% yield of (η⁵-C₅H₄C₇F₇)₂Fe (6). Reaction of ZrCl₄(THF)₂ with 2 equiv. of 5 afforded a 58% yield of (η⁵-C₇F₇C₅H₄)₂ZrCl₂ (7). Reaction of Mn(CO)₅Br with 5 afforded a 74% yield of (η⁵-C₇F₇C₅H₄)Mn(CO)₃ (8). Treatment of 3b with NaH and then with Mn(CO)₅Br in DME afforded a 26% yield of [η⁵-1,2,4-(C₇F₇)₃C₅H₂]Mn(CO)₃ (9). Treatment of 3b with NaH and then with FeBr₂ in DME afforded a trace yield of [η⁵-1,2,4-(C₇F₇)₃C₅H₂]₂Fe (10), which was not fully characterized. Dienes 2a, 3a, and 3b and metal complexes 7, 8, and 9 were structurally characterized by single-crystal X-ray diffraction. Infrared spectroscopic analysis of the substituted CpMn(CO)₃ complexes showed a linear increase of 5 cm⁻¹ in the A-symmteric stretching frequency for each C₇F₇ substituent, compared to the analogous value of 4 cm⁻¹ reported earlier for each pentafluorophenyl (C₆F₅) substituent. Solution voltammetric analysis of the substituted ferrocene 6 revealed a shift in the E_1/2 of 465 mV relative to ferrocene, compared to the analogous value of about 340 mV for 1,1′-bis(pentafluorophenyl)ferrocene.     

Oxalate-bridged dirhenium(I) hexacarbonyl complexes: synthesis, reactions, and crystal structures

The complex [{Re(CO)₅}₂(μ,η¹:η¹-C₂O₄)] 1 undergoes thermal decarbonylation to give [Re₂(CO)₆(C₂O₄)]_n, which reacts with triphenylphosphine and trans-1,2-bis(diphenylphosphino)ethylene (dppene) to give anti-[Re₂(PPh₃)₂(CO)₆(μ,η²:η²-C₂O₄)] 2 and [Re₂(μ-dppene)(CO)₆(μ,η²:η²-C₂O₄)] 4, respectively. Complex 2 is oxidized on prolonged exposure to air (1 week) to form anti-[Re₂(OPPh₃)₂(CO)₆(μ,η²:η²-C₂O₄)] 3. In the presence of excess dppene, the complex [Re₂(μ-dppene)₂(CO)₆(μ,η¹:η¹-C₂O₄)] 5 is also formed alongside 4. With the chelating diphosphine 1,3-bis(diphenylphosphino)propane (dppp), the complex [(η²-dppp)Re(CO)₃(μ,η¹:η¹-C₂O₄)Re(CO)₃(η²-dppp)] 6 is formed. The structures of 3 and 4 have been determined by X-ray crystallography. The dppene ligand in complex 4 adopts an unusual “syn” conformation wherein the two phosphorus lone pairs of electrons are eclipsed, thus forming an “A-frame” type of bridge.     

Carbonyl complexes of manganese, rhenium and molybdenum with 2-pyridylimino acid ligands

[MBr(CO)₃{κ²(N,O)-pyca}] [M = Mn(1a), Re(1b), pyca = pyridine-2-carboxaldehyde] and [MoCl(η³-C₃H₄Me-2)(CO)₂{κ²(N,O)-pyca}] (1c) react with aminoacid β-alanine to give the corresponding iminopyridine complexes 2a-2c. The same method affords the iminopyridine derivatives from γ-aminobutyric acid (GABA) (3a-3c) and 3-aminobenzoic acid (4a-4c). For complexes 2a-2c, 3a, 3c and 4a, the solid state structures have been determined by X-ray crystallography, revealing interesting differences in their hydrogen-bonding patterns in solid state.