大取代茂钼化合物的合成与结构分析

利用芳基锂与6,6-二烷基富烯发生加成反应,制得大取代环戊二烯基负离子.用六羰基钼配位,合成出13个钼-钼双核及5个钼-卤素单核羰基化合物.研究了其IR、^1HNMR、^95MoNMR.测定了[(CH~3)~2C(m-CH~3C~6H~4]Mo(CO)~3Br(1)的晶体结构.该晶体属于单余晶系,晶胞参数为a=1.175(3),b=1.4196(2),c=1.1894(4)nm,β=118.03(2)°,Ⅴ=1.75134nm^3.Z=4,D~0=1.733g/cm^3,F(000)=904,μ=30.0cm^-1,R=0.039,R~W=0.050,空间群为P2~1/α.     

Mono-, di-, and trinuclear luminescent silver(I) and gold(I) N-heterocyclic carbene complexes derived from the picolyl-substituted methylimidazolium salt: 1-methyl-3-(2-pyridinylmethyl)-1H-imidazolium tetrafluoroborate

The N-heterocyclic carbene (NHC) precursor, 1-methyl-3-(2-pyridinylmethyl)-1H-imidazolium tetrafluoroborate, [HCH3im(CH2py)]BF4, reacted with AgBF4 in the presence of aqueous NaOH to produce the silver complex [Ag(CH3im(CH2py))2]BF4 (1) which was then reacted with Au(tht)Cl to form the corresponding gold(I) complex, [Au(CH3im(CH2py))2]BF4 (2). Complex 2 reacted with 1 equiv of AgBF4 to produce the mixed-metal species [AuAg(CH3im(CH2py))2](BF4)2 (3). The reaction of 2 with 1 equiv of Au(tht)Cl followed by metathesis with NaBF4 produces the dimetallic gold complex [Au2(CH3im(CH2py))2](BF4)2 (4). The reaction of [Ag(CH3im(CH2py))2]BF4 (1) with 1 equiv of AgBF4 produces the trinuclear [Ag3(CH3im(CH2py))3(NCCH3)2](BF4)3 (5) complex, which appears to dissociate into a dimetallic complex in solution. Complexes 1-5 were characterized by 1H NMR, 13C NMR, UV-vis, luminescence spectroscopy, elemental analysis, mass spectrometry, and X-ray crystallography. The CH3im(CH2py) ligands in 3 are arranged in a head-to-head fashion spanning a Au-Ag separation of 3.0318(5) A with the carbene portion of the ligand remaining coordinated to the Au(I) center. In 4, the ligands are arranged in a head-to-tail fashion with an Au-Au separation of 3.1730(5) A. In 5, the ligands bridge the nearly symmetrical Ag3 triangular core with short Ag-Ag separations of 2.7765(8), 2.7832(8), and 2.7598(8) A. All of these complexes, including the ligand precursor, are intensely luminescent in solution and the solid state.     

Formation of dinuclear titanium and zirconium complexes by olefin metathesis--catalytic preparation of organometallic catalyst systems

The titanium complex [(C(5)H(4)bond;allyl)TiCl(3)] (2) undergoes olefin metathesis coupling when treated with 3 mol % of [Cl(2)(L(1))(L(2))Ru=CHPh] (L(1)=L(2)=PCy(3), 4 a; L(1)=PCy(3), L(2)=(H(2)IMes), 4 b) to yield the dimetallic complex [Cl(3)Ti(C(5)H(4))-CH(2)CH=CHCH(2)-(C(5)H(4))TiCl(3)] (5). The allyl-substituted titanocene complex [Cp(C(5)H(4)bond;allyl)TiCl(2)] (3) analogously yields the dimetallic system 6 when treated with 4. The ansa-zirconocene complex [Me(2)Si(C(5)H(4))(C(5)H(3)bond;allyl)ZrCl(2)] (7) cleanly yields the analogous dimetallic coupling product 8 (>95 % isomerically pure), when treated with catalytic amounts of 4 b in toluene. Complex 8 gives an active homogeneous ethene or propene polymerization catalyst, especially at elevated temperatures, when treated with excess methylalumoxane.     

Dinuclear palladium(II) compounds with bridging cyclometalated phosphines. Synthesis, crystal structure and electrochemical study

The structural characterization of bis-cyclometalated palladium(II) compounds of formula Pd2[(micro-(C6X4)PPh2]2(micro-O2CR)2 [X = H, R = CH3 (3), CF3 (4), C(CH3)3 (5) and C6F5 (6); X = F, R = CH3 (7) and CF3 (8)], has confirmed its paddle wheel structure with two palladium atoms bridged by two acetates and two metalated phosphines in a head-to-tail arrangement. The Pd...Pd distances are in the range 2.6779(16)-2.7229(8) A. Under cyclic voltammetric conditions, compounds 3-6, in CH2Cl2 solution, were found to undergo a reversible oxidation peak in the range of potential values 0.84-1.25 V. A second partially-reversible oxidation is observed at more positive potentials (1.37-1.55 V). For compounds 3-5 in the presence of chlorides, the first oxidation becomes a two-electron process presumably leading to a neutral [Pd(III)-Pd(III)] species with a metal-metal bond.     

Linear trichromium complexes with direct Cr to Cr contacts. 2. Compounds with Cr3(dipyridylamide)4(3+) cores

Seven compounds having in common a Cr3(dpa)4(3+) core (dpa = di(2-pyridyl)amide ion) have been prepared and all shown to have an unsymmetrical chain of three Cr atoms. This chain can be described as a pair of quadruply bonded Cr(II) atoms to which a Cr(III) atom is attached. No symmetrical chain has been found, contrary to a previous preliminary report. The seven compounds have been well characterized crystallographically, and their short and long Cr to Cr distances (A, in parentheses) are: 1 [Cr3(dpa)4Cl2]Cl.2CH2Cl2.THF (2.12, 2.47), 2 [Cr3(dpa)4Cl2]AlCl4.CH2Cl2 (2.011, 2.555), 3 [Cr3(dpa)4Cl2]FeCl4.CH2Cl2 (2.009, 2.562), 4 [Cr3(dpa)4Cl2]I3.THF.2H2O (2.08, 2.49), 5 [Cr3(dpa)4Cl2]PF6.2CH2Cl2 (2.08, 2.48), 6 [Cr3(dpa)4(BF4)F]BF4.2CH2Cl2 (1.900, 2.595), 7 [Cr3(dpa)4ClF]BF4.CH2Cl2.C6H14 (2.039, 2.507). Magnetic susceptibility measurements on 1 and 2 reveal mueff = 3.85 +/- 0.05 muB from 10 to 300 K.     

Electronic structure of iron chlorins: characterization of bis(l-valine methyl ester)(meso-tetraphenylchlorin)iron(III)triflate and bis(l-valine methyl ester)(meso-tetraphenylchlorin)iron(II)

The synthesis and characterization of the two iron chlorin complexes [Fe(III)(TPC)(NH(2)CH(CO(2)CH(3))(CH(CH(3))(2)))(2)]CF(3)SO(3) (1) and Fe(II)(TPC)[(NH(2)CH(CO(2)CH(3))(CH(CH(3))(2))](2) (2) are reported. The crystal structure of complex 1 has been determined. The X-ray structure shows that the porphyrinate rings are weakly distorted. The metal-nitrogen distances to the reduced pyrrole N(4), 2.034(4) A, and to the pyrrole trans to it N(2), 2.012(4) A, are longer than the distances to the two remaining nitrogens [N(1), 1.996(4) A, and N(3), 1.984(4) A], leading to a core-hole expansion of the macrocycle due to the reduced pyrrole. The (1)H NMR isotropic shifts at 20 degrees C of the different pyrrole protons of 1 varied from -0.8 to -48.3 ppm according to bis-ligated complexes of low-spin ferric chlorins. The EPR spectrum of [Fe(TPC)(NH(2)CH(CO(2)CH(3))(CH(CH(3))(2)))(2)]CF(3)SO(3) (1) in solution is rhombic and gives the principal g values g(1) = 2.70, g(2) = 2.33, and g(3) = 1.61 (Sigmag(2) = 15.3). These spectroscopic observations are indicative of a metal-based electron in the d(pi) orbital for the [Fe(TPC)(NH(2)CH(CO(2)CH(3))(CH(CH(3))(2)))(2)]CF(3)SO(3) (1) complex with a (d(xy))(2)(d(xz)d(yz))(3) ground state at any temperature. The X-ray structure of the ferrous complex 2 also shows that the porphyrinate rings are weakly distorted. The metal-nitrogen distances to the reduced pyrrole N(4), 1.991(5) A, and to the pyrrole trans to it N(2), 2.005(6) A, are slightly different from the distances to the two remaining nitrogens [N(1), 1.988(5) A, and N(3), 2.015(5) A], leading to a core-hole expansion of the macrocycle due to the reduced pyrrole.     

Synthesis, crystal structures and magnetic behaviour of dimeric and tetrameric gadolinium carboxylates with trichloroacetic acid

The novel gadolinium(III) containing compounds (CH3NH3)2[Gd2(CCl3COO)6(H2O)6](CCl3COO)2.2CCl3COOH (1) and (NH3CH3)2[Gd4(OH)4(CCl3COO)10(H2O)6].2H2O (2) were synthesized and structurally characterized by X-ray crystallography. In the crystal structure of 1 the gadolinium ions are bridged by carboxylate groups to dimers with a Gd3+ -Gd3+ distance of 420.2(3) pm. The compound crystallizes in the triclinic space group P1. In the crystal structure of the Gd3+ ions are bridged by hydroxide ions and carboxylate groups to tetramers with Gd3+ -Gd3+ distances between 380.3(1) and 388.0(1) pm. The compound crystallizes in the triclinic space group P1. The magnetic behaviour of these two compounds as well as of Gd2(CCl3COO)6(bipy)2(H2O)2.4bipy (3) (bipy = 2,2'-bipyridyl) was investigated in the temperature range 1.77-300 K. The magnetic data for these compounds indicate weak antiferromagnetic interactions.     

Divalent molybdenum complexes of the dipyrrolide ligand system. Isolation of a Mo2 unit with a 45 degree twist angle

The preparation of divalent Mo complexes of dipyrrolide dianions was carried out by reacting Mo(2)(acetate)(4) with the dipotassium salts of Ph(2)C(2-C(4)H(3)NH)(2) and 2-[1,1-bis(1H-pyrrol-2-yl)ethyl]pyridine. The two reactions respectively afforded the diamagnetic [[Ph(2)C(C(4)H(3)N)(2)](2)Mo(2)(OAc)(2)[K(THF)(3)][K(THF)]].THF (1) and [[(2-C(5)H(4) N)(CH(3))C(2-C(4)H(3)N)(2)]Mo(OAc)[K(THF)]](2).THF (2). Both compounds retained two acetate units in the dimetallic structure. Conversely, the reaction of Me(8)Mo(2)Li(4)(THF)(4) with Et(2)C(2-C(4)H(3)NH)(2) afforded the paramagnetic dimer [[Et(2)C(C(4)H(3)N)(2)](4)Mo(2)Li(2)][Li(THF)(4)](2).0.5THF (3). The paramagnetism is most likely caused by the 45 degree rotation of the two Mo(dipyrrolide) units with respect to each other and which, in turn, is caused by the presence of two lithium cations in the molecular structure.     

Tethered olefin studies of alkene versus tetraphenylborate coordination and lanthanide olefin interactions in metallocenes

The tethered olefin cyclopentadienyl ligand, [(C(5)Me(4))SiMe(2)(CH(2)CH=CH(2))](-), forms unsolvated metallocenes, [(C(5)Me(4))SiMe(2)(CH(2)CH=CH(2))](2)Ln (Ln = Sm, 1; Eu, 2; Yb, 3), from [(C(5)Me(4))SiMe(2)(CH(2)CH=CH(2))]K and LnI(2)(THF)(2) in good yield. Each complex in the solid state has both tethered olefins oriented toward the Ln metal center with the Ln-C(terminal alkene carbon) distances 0.2-0.3 A shorter than the Ln-C(internal alkene carbon) distances. The olefinic C-C bond distances in 2 and 3, 1.328(4) and 1.328(5) A, respectively, are normal. Like its permethyl analogue, (C(5)Me(5))(2)Sm(THF)(2), complex 1 reductively couples CO(2) to form the oxalate-bridged dimer [[(C(5)Me(4))SiMe(2)(CH(2)CH=CH(2))](2)Sm](2)(mu-eta(2):eta(2)-O(2)CCO(2)), 4, in which the tethered olefins are noninteracting substituents. Complex 1 reacts with AgBPh(4) to form an unsolvated cation that has the option of coordinating [BPh(4)](-) or a pendant olefin, a competition common in olefin polymerization catalysis. The structure of [[(C(5)Me(4))SiMe(2)(CH(2)CH=CH(2))](2)Sm][BPh(4)], 5, shows that both pendant olefins are located near samarium rather than the [BPh(4)](-) counterion.     

Fe(CO)4 and related compounds as isolobal fragments

The M(CO)(4) fragment can be assigned to be isolobal with both CH(3)(+) and CH(2). In order to investigate this ambiguous isolobal assignment, we report calculations on compounds of the type M(CO)(4)L(n), where M is Fe (n = 0), Mn (n = -1), and Co (n = +1) and L is an η(2) ligand with a π bond, generally an alkene. The L's are varied in electron-withdrawing ability, and patterns in computed structural parameters are investigated. We report that the equatorial OC-M-CO angle is sensitive to the electron-withdrawing ability of the alkene just as the isolobal prediction suggests. Other structural parameters that vary monotonically with electron-withdrawing ability of the alkene are the "bending back" of the alkene, the metal-ligand bond distances, and carbon-oxygen bond distances. Changing the metal from neutral Fe to a negatively charged Mn or positively charged Co has the result of increasing and decreasing, respectively, the OC-M-CO angle. Several compounds of Ni(CO)(3)L are also investigated as a further example of the ability of the isolobal concept to yield chemically useful information.     

Carbon Monoxide and Cyanide Ligands in a Classical Organometallic Complex Model for Fe-Only Hydrogenase

The Fe(I) organometallic complex [(μ-SCH(2)CH(2)CH(2)S)Fe(2)(CO)(6)] provides a structural model for the cyano-carbonyl diiron site of Fe-only hydrogenase as characterized by X-ray crystallography (the picture shows the structure (black) of the model overlaid with that of the Fe-Fe dimetallic site in the hydrogenase isolated from Desulfovibrio desulfuricans). Cyanide substitution of CO occurs readily and provides spectroscopic references for the active site.     

Molecularly nonstoichiometric crystals in phosphorus compounds

Molecularly nonstoichiometric crystals obtained as a result of differential occupation of sites with oxygen atom/phosphorus lone pair of electrons or with sulfur/selenium in three sets of phosphorus compounds are described. These are formed by a combination of (a) [CH2(6-t-Bu-4-MeC6H2O)2]PNMe2 (11) and [CH2(6-t-Bu-4-MeC6H2O)2]P(O)NMe2 (13), (b) [CH2(6-t-Bu-4-MeC6H2O)2]P(S)NMe2 (14) and [CH2(6-t-Bu-4-MeC6H2O)2]P(Se)NMe2 (15), and (c) [(2,6-Me2C6H3O)(O)P-micro-N-t-Bu]2 (16) and (2,6-Me2C6H3O)(O)P(micro-N-t-Bu)2P(O-2,6-Me2C6H3) (17). In the case of c, three different types of crystals with varying stoichiometry of 16 and 17 (1:9, 1:1.5, and 1:0.43) are obtained. The results are substantiated by the combined use of 31P NMR spectroscopy and X-ray crystallography. These observations suggest that we should be cautious with regards to the purity of samples when syntheses involving the oxidation of P(III) systems are reported. It is also emphasized that the apparent P-X distances in some of these crystals cannot actually be taken as true bond lengths.     

Programmable self-assembly of homo- or hetero-metallomacrocycles using 4-(1H-pyrazolyl-4-yl)pyridine

The dimetallic [M(2)(bpy)(2)(NO(3))(2)](NO(3))(2) moieties (M = Pd(II) or Pt(II)) react preferentially at the pyrazolyl end of the pyridyl-pyrazole ligand, giving rise to dimetallic corners. Subsequently, the dimetallic corner building blocks featuring two pyridine donors are coordinated by monometallic [M(bpy)(NO(3))(2)] moieties (M = Pd(II) or Pt(II)) to form homo- or hetero-metallomacrocycles.     

Vibrational study of (CH3)4NSbCl6 and [(CH3)4N]2SiF6

(CH3)4NSbCl6 and [(CH3)4N]2SiF6 are face-centred cubic compounds at ambient temperature with a = 11.548 and 11.172 A, respectively. The vibrational spectra of these two compounds are discussed in relation to their crystal structure and other compounds containing (CH3)4N+ ions. The assignment of the observed bands is discussed. The Raman and infrared spectra of [(CH3)4N]2SiF6 show that the cations and anions are not distorted inside the crystals and are weakly hydrogen-bonded to each other. The infrared spectrum of (CH3)4NSbCl6 confirms a cubic structure for this compound at ambient temperature, in which cations are in octahedral environments and can be interpreted as being disordered groups. No evidence could be found for the existence of hydrogen bonding between cations and anions in this compound. The phase transition of (CH3)4NSbCI6 is studied by means of Raman spectroscopy. It is believed to be governed by the reorientational motions of tetramethylammonium cations and may be classified as an 'order-disorder' type.     

Syntheses, structures and properties of a series of non-heme alkoxide-Fe(III) complexes of a benzimidazolyl-rich ligand as models for lipoxygenase

The treatment of Fe(ClO(4))(2)·6H(2)O or Fe(ClO(4))(3)·9H(2)O with a benzimidazolyl-rich ligand, N,N,N',N'-tetrakis[(1-methyl-2-benzimidazolyl)methyl]-1,2-ethanediamine (medtb) in alcohol/MeCN gives a mononuclear ferrous complex, [Fe(II)(medtb)](ClO(4))(2)·?CH(3)CN·?CH(3)OH (1), and four non-heme alkoxide-iron(III) complexes, [Fe(III)(OMe)(medtb)](ClO(4))(2)·H(2)O (2, alcohol = MeOH), [Fe(III)(OEt)(Hmedtb)](ClO(4))(3)·CH(3)CN (3, alcohol = EtOH), [Fe(III)(O(n)Pr)(Hmedtb)](ClO(4))(3)·(n)PrOH·2CH(3)CN (4, alcohol = n-PrOH), and [Fe(III)(O(n)Bu)(Hmedtb)](ClO(4))(3)·3CH(3)CN·H(2)O (5, alcohol = n-BuOH), respectively. The alkoxide-iron(III) complexes all show 1) a Fe(III)-OR center (R = Me, 2; Et, 3; (n)Pr, 4; (n)Bu, 5) with the Fe-O bond distances in the range of 1.781-1.816 ?, and 2) a yellow color and an intense electronic transition around 370 nm. The alkoxide-iron(III) complexes can be reduced by organic compounds with a cis,cis-1,4-diene moiety via the hydrogen atom abstraction reaction.     

Synthesis, X-ray diffraction studies, and DFT calculations on hexacoordinated germanium derivatives: the case of germaspirobis(ocanes)

Synthesis of the title compounds, viz. [RN(CH2CHR'O)2]2Ge (1, R = Me, R' = H; 2, R = Me, R' = Ph; 3, R = Ph, R' = H), by the reaction of 2 equiv of corresponding dialkanolamines RN(CH2CHR'OH)2 (4, R = Me, R' = H; 5, R = Me, R' = Ph; 6, R = Ph, R' = H) with (AlkO)4Ge is reported. Composition and structures of all novel compounds were established by 1H and 13C NMR spectroscopy and mass spectrometry as well as elemental analysis data. The single-crystal X-ray diffraction of 2 has clearly indicated the presence of two transannular interactions Ge<--N in the compound. N atoms are cis-orientated. The compound 3 possesses long Ge...N distances. The structural data obtained from geometry optimizations by DFT calculations on 1-3 reproduces experimental results. Both cis- and trans-isomers were studied, and cis-configuration was found to be more thermodynamically stable for all three compounds. The transition states for possible cis <--> trans rearrangement processes in 1-3 were calculated. The properties of the Ge-O and Ge<--N bonds in 1-3 were analyzed by the AIM approach. The interactions between the Ge atom and N atoms as well as O atoms possess predominantly ionic character.     

Electrical conductivity and luminescence in coordination polymers based on copper(I)-halides and sulfur-pyrimidine ligands

The solvothermal reactions between pyrimidinedisulfide (pym(2)S(2)) and CuI or CuBr(2) in CH(2)Cl(2):CH(3)CN lead to the formation of [Cu(11)I(7)(pymS)(4)](n) (pymSH = pyrimidine-2(1H)-thione) (1) and the dimer [Cu(II)(μ-Br)(Br)L](2) (L = 2-(pyrimidin-2-ylamino)-1,3-thiazole-4-carbaldehyde) (2). In the later reaction, there is an in situ S-S, S-C(sp(2)), and C(sp(2))-N multiple bond cleavage of the pyrimidinedisulfide resulting in the formation of 2-(pyrimidin-2-ylamino)-1,3-thiazole-4-carbaldehyde. Interestingly, similar reactions carried out just with a change in the solvent (H(2)O:CH(3)CN instead of CH(2)Cl(2):CH(3)CN) give rise to the formation of coordination polymers with rather different architectures. Thus, the reaction between pym(2)S(2) and CuI leads to the formation of [Cu(3)I(pymS)(2)](n) (3) and [CuI(pym(2)S(3))] (pym(2)S(3) = pyrimidiltrisulfide) (4), while [Cu(3)Br(pymS)(2)](n) (5) is isolated in the reaction with CuBr(2). Finally, the solvothermal reactions between CuI and pyrimidine-2-thione (pymSH) in CH(2)Cl(2):CH(3)CN at different ratios, 1:1 or 2:1, give the polymers [Cu(2)I(2)(pymSH)(2)](n) (6) and [Cu(2)I(2)(pymSH)](n) (7), respectively. The structure of the new compounds has been determined by X-ray diffraction. The studies of the physical properties of the novel coordination polymers reveal that compounds 3 and 5 present excellent electrical conductivity values at room temperature, while compounds 1, 3, and 5-7 show luminescent strong red emission at room temperature.     

Synthesis and characterization of zinc AP-MOCVD precursors and their utility in the growth of ZnO

A novel beta-ketoimine, 4-N-(n-butylamino)-3-penten-2-one (1), and beta-enaminoester, Ethyl 3-N-(isopropylamino)-2-butenoate (2), were synthesized by the reaction of the 2,4-pentanedione or ethyl 3-oxo butanoate with the n-butyl and isopropyl amine, respectively. The isolated free ligands 1 and 2 were reacted with diethylzinc to afford Zn(CH3C(NCH2CH2CH2CH3)CHCOCH3)2 (3) and Zn(CH3C(NCH(CH3)2)CHC(O)OCH2CH3)2 (4) respectively. The isolated zinc complexes, 3 and 4, were characterized by elemental analysis, NMR, and MALDI-TOFMS. The molecular structure of 3 and 4 were determined via single crystal X-ray diffraction which revealed both compounds to be four coordinate, monomeric and homoleptic in the solid state. TG analysis showed the air stable compounds to be thermally robust as they both sublimed in a one-step process at atmospheric pressure. The compounds were utilized in the growth of ZnO via AP-MOCVD in the absence of additional oxidant. The carbon content of the film grown from 3 as determined by XPS was 26.2% while that of the film grown by 4 was 8.71%.     

Synthesis and vibrational circular dichroism of enantiopure chiral oxorhenium(V) complexes containing the hydrotris(1-pyrazolyl)borate ligand

The infrared and vibrational circular dichroism (VCD) spectra of six chiral oxorhenium(V) complexes, bearing a hydrotris(1-pyrazolyl)borate (Tp) ligand, have been investigated. These complexes are promising candidates for observation of parity violation (symmetry breaking due to the weak nuclear force). New chiral oxorhenium complexes have been synthesized, namely, [TpReO(eta2-O(CH3)CH2CH2O-O,O)] (4a and 4b) diastereomers and [TpReO(eta2-N(CH3)CH2CH2O-N,O)] (5) and [TpReO(eta2-N(tBu)CH2CH2O-N,O)] (6) enantiomers. All compounds could be obtained in enantiomerically pure form by using either column chromatography or HPLC over chiral columns. VCD spectroscopy of these compounds and of [TpReO(eta2-N(CH3)CH(CH3)CH(Ph)O-N,O)] (2) and [TpReO(eta2-N(CH2)3CHCO2-N,O)] (3) (with chiral bidentate ligands derived, respectively, from ephedrine and proline) were studied. This allowed the absolute configuration determination of all compounds together with their conformational analysis, by comparing calculated and experimental spectra. This is the first VCD study of rhenium complexes which further demonstrates the applicability of VCD spectroscopy in determining the chirality of inorganic complexes.     

Olefin metathesis as an inorganic synthetic tool: cross and ring closing metathesis reactions of diruthenium-bound omega-alkene-alpha-carboxylates

Diruthenium compounds containing one omega-alkene-alpha-carboxylate ligand, Ru2Cl(D(3,5-Cl2Ph)F)3(O2C(CH2)nCH=CH2) (n=1 (1a) and 2 (1b)), were prepared from the reaction between Ru2Cl(D(3,5-Cl2Ph)F)3(O2CCH3) (D(3,5-Cl2Ph)F=N,N'-bis(3,5-dicholorophenyl)formamidinate) and the corresponding omega-alkene-alpha-carboxylic acid. Compounds 1a and 1b both underwent olefin cross metathesis reactions catalyzed by (Cy3P)2Cl2Ru(=CHPh) to afford the dimerized compounds [Ru2Cl(D(3,5-Cl2Ph)F)3]2(mu-O2C(CH2)nCH=CH(CH2)nCO2) (n=1 (2a) and 2 (2b)). Similarly, diruthenium compounds containing two omega-alkene-alpha-carboxylate ligands, cis-Ru2Cl(D(3,5-Cl2Ph)F)2(O2C(CH2)nCH=CH2)2 (n=1 (3a), 2 (3b), and 3 (3c)), were prepared by substituting the acetate ligands in cis-Ru2Cl(D(3,5-Cl2Ph)F)2(O2CCH3)2 with the corresponding omega-alkene-alpha-carboxylate ligands. Compounds 3 exhibited different reactivity under olefin metathesis conditions: both 3b and 3c underwent the intramolecular ring closing reaction quantitatively to afford compounds cis-Ru2(D(3,5-Cl2Ph)F)2(mu-O2C(CH2)nCH=CH2(CH2)nCO2)Cl with n=2 (4b) and 3 (4c), respectively, but 3a displayed no metathesis reactivity. Molecular structures of compounds 1a/1b, 2a/2b, 3a/3b, and 4b were established via X-ray diffraction studies, confirming the formation of cross and ring closing metathesis products. Voltammograms of compounds 2 are nearly identical to those of compounds 1, indicating the absence of electronic interactions mediated by the tether derived from olefin metathesis.