Structural and kinetic study of reversible CO2 fixation by dicopper macrocyclic complexes. From intramolecular binding to self-assembly of molecular boxes

A study of the reversible CO2 fixation by a series of macrocyclic dicopper complexes is described. The dicopper macrocyclic complexes [Cu2(OH)2(Me2p)](CF3SO3)2, 1(CF3SO3)2, and [Cu2(mu-OH)2(Me2m)](CF3SO3)2, 2(CF3SO3)2, (Scheme 1) containing terminally bound and bridging hydroxide ligands, respectively, promote reversible inter- and intramolecular CO2 fixation that results in the formation of the carbonate complexes [{Cu2(Me2p)}2(mu-CO3)2](CF3SO3)4, 4(CF3SO3)4, and [Cu2(mu-CO3)(Me2m)](CF3SO3)2, 5(CF3SO3)2. Under a N2 atmosphere the complexes evolve CO2 and revert to the starting hydroxo complexes 1(CF3SO3)2 and 2(CF3SO3)2, a reaction the rate of which linearly depends on [H2O]. In the presence of water, attempts to crystallize 5(CF3SO3)2 afford [{Cu2(Me2m)(H2O)}2(mu-CO3)2](CF3SO3)4, 6(CF3SO3)4, which appears to rapidly convert to 5(CF3SO3)2 in acetonitrile solution. [Cu2(OH)2(H3m)]2+, 7, which contains a larger macrocyclic ligand, irreversibly reacts with atmospheric CO2 to generate cagelike [{Cu2(H3m)}2(mu-CO3)2](ClO4)4, 8(ClO4)4. However, addition of 1 equiv of HClO4 per Cu generates [Cu2(H3m)(CH3CN)4]4+ (3), and subsequent addition of Et3N under air reassembles 8. The carbonate complexes 4(CF3SO3)4, 5(CF3SO3)2, 6(CF3SO3)4, and 8(ClO4)4 have been characterized in the solid state by X-ray crystallography. This analysis reveals that 4(CF3SO3)4, 6(CF3SO3)4, and 8(ClO4)4 consist of self-assembled molecular boxes containing two macrocyclic dicopper complexes, bridged by CO32- ligands. The bridging mode of the carbonate ligand is anti-anti-mu-eta1:eta1 in 4(CF3SO3)4, anti-anti-mu-eta2:eta1 in 6(CF3SO3)4 and anti-anti-mu-eta2:eta2 in 5(CF3SO3)2 and 8(ClO4)4. Magnetic susceptibility measurements on 4(CF3SO3)4, 6(CF3SO3)4, and 8(ClO4)4 indicate that the carbonate ligands mediate antiferromagnetic coupling between each pair of bridged CuII ions (J = -23.1, -108.3, and -163.4 cm-1, respectively, H = -JS1S2). Detailed kinetic analyses of the reaction between carbon dioxide and the macrocyclic complexes 1(CF3SO3)2 and 2(CF3SO3)2 suggest that it is actually hydrogen carbonate formed in aqueous solution on dissolving CO2 that is responsible for the observed formation of the different carbonate complexes controlled by the binding mode of the hydroxy ligands. This study shows that CO2 fixation can be used as an on/off switch for the reversible self-assembly of supramolecular structures based on macrocyclic dicopper complexes.     

Peripheral SH-functionalisation of carbosilane dendrimers including the synthesis of the model compound dimethylbis(propanethiol)silane and their interaction with rhodium complexes

Treatment of the allyl-containing compounds Me2Si(CH2CHCH2)2 and MeSi(CH2CHCH2)3 with thioacetic acid in the presence of AIBN gave Me2Si[(CH2)3SC(O)CH3]2 and MeSi[(CH2)3SC(O)CH3]3, respectively, which were reduced with LiAlH4 to the dithiols Me2Si[(CH2)3SH]2(3) and MeSi[(CH2)3SH]3(4). This protocol was applied to the first and second generations of the doubly and triply-branched carbosilane allyl dendrimers, Si[(CH2)3SiMe(CH2CHCH2)2]4(G(1)allyl-8), Si[(CH2)3SiMe{(CH2)3SiMe(CH2CHCH2)2}2]4(G(2)allyl-16), Si[(CH2)3Si(CH2CHCH2)3]4(G(1)allyl-12), and Si[(CH2)3Si{(CH2)3Si(CH2CHCH2)3}3]4(G(2)allyl-36) to give the corresponding SH functionalised surface dendrimers Si[(CH2)3SiMe(CH2CH2CH2SH)2]4(G(1)SH-8), G(2)SH-16, G(1)SH-12, and G(2)SH-36. Reactions of 3 with [M(acac)(diolefin)](M = Rh, Ir; diolefin = 1,5-cyclooctadiene, 2,5-norbornadiene) gave the compounds of the type [M2(mu-Me2Si[(CH2)3S]2)(diolefin)2]n. These diolefin complexes are octanuclear (n= 4) in solution while the complex [Rh2(mu-Me2Si[(CH2)3S]2)(cod)2]n(5) is tetranuclear in the solid state. The structure of 5, solved by X-ray diffraction methods, consists of a 20-membered metallomacrocycle formed by two dimethylbis(propylthiolate)silane moieties bridging four fragments Rh(cod) in a mu2 fashion through the sulfur atoms. Treatment of [Rh(acac)(CO)2] with 3 gave [Rh2(mu-Me2Si[(CH2)3S]2)(CO)4]n, which is a mixture of tetra (n= 2) and octanuclear (n= 4) complexes in a 2 : 1 ratio in solution, while the related complex [Rh2(mu-Me2Si[(CH2)3S]2)(CO)2(PPh3)2]2 is tetranuclear. Reactions of [Rh(acac)(L-L)](L-L = cod, (CO)2, (CO)(PPh3)) with 4 and the dendrimers G(1)SH-8, G(2)SH-16, and G(1)SH-12, gave microcrystalline solids of formulae [Rh3(MeSi[(CH2)3S]3)(L-L)3]n, [Si[(CH2)3SiMe{(CH2)3SRh(cod)}2]4]n([G(1)Rh(cod)-8]n), [Si[(CH2)3Si{(CH2)3SRh(cod)}3]4]n([G(1)Rh(cod)-12]n), etc., which presumably are tridimensional coordination polymers.     

Sensitivity of silver(I) complexes of a pyrimidine-hydrazone ligand to solvent, counteranion, and metal-to-ligand ratio changes

Metal complexation studies were performed with AgSO(3)CF(3) and AgBF(4) and the ditopic pyrimidine-hydrazone ligand 6-(hydroxymethyl)pyridine-2-carboxaldehyde (2-methylpyrimidine-4,6-diyl)bis(1-methylhydrazone) (1) in both CH(3)CN and CH(3)NO(2) in a variety of metal-to-ligand ratios. The resulting complexes were studied in solution by NMR spectroscopy and in the solid state by X-ray crystallography. Reacting either AgSO(3)CF(3) or AgBF(4) with 1 in either CH(3)CN or CH(3)NO(2) in a 1:1 metal-to-ligand ratio produced a double helicate in solution. This double helicate could be converted into a linear complex by increasing the metal-to-ligand ratio; however, the degree of conversion depended on the solvent and counteranion used. Attempts to crystallize the linear AgSO(3)CF(3) complex resulted in crystals with the dimeric structure [Ag(2)1(CH(3)CN)(2)](2)(SO(3)CF(3))(4) (2), while attempts to crystallize the AgSO(3)CF(3) double helicate from CH(3)CN resulted in crystals of another dimeric complex, [Ag(2)1(SO(3)CF(3))(CH(3)CN)(2)](2)(SO(3)CF(3))(2)·H(2)O (3). The AgSO(3)CF(3) double helicate was successfully crystallized from a mixture of CH(3)CN and CH(3)NO(2) and had the structure [Ag(2)1(2)](SO(3)CF(3))(2)·3CH(3)NO(2) (4). The linear AgBF(4) complex could not be isolated from the double helicate in solution; however, crystals grown from a solution containing both the AgBF(4) double helicate and linear complexes in CH(3)CN had the structure [Ag(2)1(CH(3)CN)(2)](BF(4))(2) (5). The AgBF(4) double helicate could only be crystallized from CH(3)NO(2) and had the structure [Ag(2)1(2)](BF(4))(2)·2CH(3)NO(2) (6).     

Synthesis and structure of new carborane-substituted cyclotriphosphazenes

The reactions of [N(3)P(3)Cl(6)] with one, two, or three equivalents of the difunctional 1,2-closo-carborane C(2)B(10)H(10)[CH(2)OH](2) and K(2)CO(3) in acetone have been investigated. These reactions led to the new spiro-closo-carboranylphosphazenes gem-[N(3)P(3)Cl(6-2n)[(OCH(2))(2)C(2)B(10)H(10)](n)] (n=1 (1), 2 (2)) and the first fully carborane-substituted phosphazene gem-[N(3)P(3)[(OCH(2))(2)C(2)B(10)H(10)](3)] (3). A bridged product, non-gem-[N(3)P(3)Cl(4)[(OCH(2))(2)C(2)B(10)H(10)]] (4), was also detected. The reaction of the well-known spiro derivatives [N(3)P(3)Cl(2)(O(2)C(12)H(8))(2)] and [N(3)P(3)Cl(4)(O(2)C(12)H(8))] with the same carborane-diol and K(2)CO(3) in acetone gave the new compounds gem-[N(3)P(3)(O(2)C(12)H(8))(3-n)[(OCH(2))(2)C(2)B(10)H(10)](n)] (n=1 (5) or 2 (6), respectively), without signs of intra- or intermolecularly bridged species. Upon treatment with NEt(3) in acetone, compound 5 was converted into the corresponding nido-carboranylphosphazene. However, the reaction of gem-[N(3)P(3)(O(2)C(12)H(8))(2)[(OCH(2))(2)C(2)B(10)H(10)]] (5) with NEt(3) in ethanol instead of acetone proceeded in a different manner to give the new compound (NHEt(3))(2)[N(3)P(3)(O(2)C(12)H(8))(2)(O)[OCH(2)C(2)B(9)H(10)CH(2)OCH(2)CH(3)]] (7). For compounds with two 2,2'-dioxybiphenyl units, gem-[N(3)P(3)(O(2)C(12)H(8))(2)[(OCH(2))(2)C(2)B(10)H(10)]] (5), (NHEt(3))[N(3)P(3)(O(2)C(12)H(8))(2)[(OCH(2))(2)C(2)B(9)H(10)]] (8), and (NHEt(3))(2)[N(3)P(3)(O(2)C(12)H(8))(2)(O)[OCH(2)C(2)B(9)H(10)CH(2)OCH(2)CH(3)]] (7), a mixture of different stereoisomers may be expected. However, for 5 and 7 only the meso compounds seem to be formed, with the same (R,S)-configuration as in the precursor [N(3)P(3)Cl(2)(O(2)C(12)H(8))(2)]. The reaction of 5 to give 8 seems to proceed with a change of configuration at one phosphorus center, giving a racemic mixture. The crystal structures of the nido-carboranylphosphazenes 7 and 8 have been confirmed by X-ray diffraction methods.     

Hydrogenation studies involving halobis(phosphine)-rhodium(I) dimers: use of parahydrogen induced polarisation to detect species present at low concentration

Reaction of [RhCl(PPh3)2]2 with parahydrogen revealed that the binuclear dihydride [Rh(H)2(PPh3)2mu-Cl)2Rh(PPh3)2] and the tetrahydride complex [Rh(H)2(PPh3)2(mu-Cl)]2 are readily formed. While magnetisation transfer from free H2 into both the hydride resonances of the tetrahydride and [Rh(H)2Cl(PPh3)3] is observable, neither transfer into [Rh(H)2(PPh3)2(mu-Cl)2Rh(PPh3)2] nor transfer between the two binuclear complexes is seen. Consequently [Rh(H)2(PPh3)2(mu-Cl)]2 and [Rh(H)2(PPh3)2(mu-Cl)2Rh(PPh3)2] are not connected on the NMR timescale by simple elimination or addition of H2. The rapid exchange of free H2 into the tetrahydride proceeds via reversible halide bridge rupture and the formation of [Rh(H)2(PPh3)2(mu-Cl)RhCl(H)2(PPh3)2]. When these reactions are examined in CD2Cl2, the formation of the solvent complex [Rh(H)2(PPh3)2(mu-Cl)2Rh(CD2Cl2)(PPh3)] and the deactivation products [Rh(Cl)(H)PPh3)2(mu-Cl)(mu-H)Rh(Cl)(H)PPh3)2] and [Rh(Cl)(H)(CD2Cl2)(PPh3)(mu-Cl)(mu-H)Rh(Cl)(H)PPh3)2] is indicated. In the presence of an alkene and parahydrogen, signals corresponding to binuclear complexes of the type [Rh(H)2(PPh3)2(mu-Cl)(2)(Rh)(PPh3)(alkene)] are detected. These complexes undergo intramolecular hydride interchange in a process that is independent of the concentration of styrene and catalyst and involves halide bridge rupture, followed by rotation about the remaining Rh-Cl bridge, and bridge re-establishment. This process is facilitated by electron rich alkenes. Magnetisation transfer from the hydride ligands of these complexes into the alkyl group of the hydrogenation product is also observed. Hydrogenation is proposed to proceed via binuclear complex fragmentation and trapping of the resultant intermediate [RhCl(H)2PPh3)2] by the alkene. Studies on a number of other binuclear dihydride complexes including [(H)(Cl)Rh(PMe3)2(mu-H)(mu-Cl)Rh(CO)(PMe3)], [(H)2Rh(PMe3)2(mu-Cl)2Rh(CO)(PMe3)] and [HRh(PMe3)2(mu-H)(mu-Cl)2Rh(CO)(PMe3)] reveal that such species are able to play a similar role in hydrogenation catalysis. When the analogous iodide complexes [RhIPPh3)2]2 and [RhI(PPh3)3] are examined, [Rh(H)2(PPh3)2(mu-I)2Rh(PPh3)2], [Rh(H)2(PPh3)2(mu-I)]2 and [Rh(H)2I(PPh3)3] are observed in addition to the corresponding binuclear alkene-dihydride products. The higher initial activity of these precursors is offset by the formation of the trirhodium phosphide bridged deactivation product, [[(H)(PPh3)Rh(mu-H)(mu-I)(mu-PPh2)Rh(H)(PPh3)](mu-I)2Rh(H)2PPh3)2]     

Preparation of tungsten alkyl alkylidene alkylidyne complexes and kinetic studies of their formation

An equilibrium mixture of alkyl alkylidyne W(CH2SiMe3)3(CSiMe3)(PMe3) (1a) and its bis(alkylidene) tautomer W(CH2SiMe3)2(=CHSiMe3)2(PMe3) (1b) has been found to undergo an alpha-hydrogen abstraction reaction in the presence of PMe3 to form alkyl alkylidene alkylidyne W(CH2SiMe3)(=CHSiMe3)(CSiMe3)(PMe3)2 (2). In the presence of PMe3, the formation of 2 follows first-order kinetics, and the observed rate constant was found to be independent of the concentration of PMe3. The activation parameters for the formation of 2 are Delta H = 28.3(1.7) kcal/mol and Delta S = 3(5) eu. In the presence of PMe2Ph, an equilibrium mixture of W(CH2SiMe3)3(CSiMe3)(PMe2Ph) (3a) and its bis(alkylidene) tautomer W(CH2SiMe3)2(=CHSiMe3)2(PMe2Ph) (3b) was similarly converted to W(CH2SiMe3)(=CHSiMe3)(CSiMe3)(PMe2Ph)2 (4). The observed rate of this reaction was also independent of the concentration of PMe2Ph. These observations suggest a pathway in which the tautomeric mixtures 1a,b and 3a,b undergo rate-determining, alpha-hydrogen abstraction, followed by phosphine coordination, resulting in the formation of the alkyl alkylidene alkylidyne complexes 2 and 4.     

Polymetallic clusters of iron(III) with derivatised salicylaldoximes

The synthesis and magnetic properties of the compounds [HNEt(3)][Fe(2)(OMe)(Ph-sao)(2) (Ph-saoH)(2)].5MeOH (1.5MeOH), [Fe(3)O(Et-sao)(O(2)CPh)(5)(MeOH)(2)].3MeOH (2.3MeOH), [Fe(4)(Me-sao)(4)(Me-saoH)(4)] (3), [HNEt(3)](2)[Fe(6)O(2)(Me-sao)(4)(SO(4))(2)(OMe)(4)(MeOH)(2)] (4), [Fe(8)O(3)(Me-sao)(3)(tea)(teaH)(3)(O(2)CMe)(3)] (5), [Fe(8)O(3)(Et-sao)(3)(tea)(teaH)(3)(O(2)CMe)(3)] (6), and [Fe(8)O(3)(Ph-sao)(3)(tea)(teaH)(3)(O(2)CMe)(3)] (7) are reported (Me-saoH(2) is 2'-hydroxyacetophenone oxime, Et-saoH(2) is 2'-hydroxypropiophenone oxime and Ph-saoH(2) is 2-hydroxybenzophenone oxime). 1-7 are the first Fe(III) compounds synthesised using the derivatised salicylaldoxime ligands, R-saoH(2). 1 is prepared by treatment of Fe(2)(SO(4))(3).6H(2)O with Ph-saoH(2) in the presence of NEt(3) in MeOH; 2 prepared by treatment of Fe(ClO(4))(2).6H(2)O with Et-saoH(2) and NaO(2)CPh in the presence of NEt(4)OH in MeOH; 3 prepared by treatment of Fe(ClO(4))(2).6H(2)O with Me-saoH(2) and NaO(2)CCMe(3) in the presence of NEt(4)OH in MeOH; and 4 prepared by treatment of Fe(2)(SO(4))(3).6H(2)O with Me-saoH(2) in the presence of NEt(3) in MeOH. 4 is a rare example of a polynuclear iron complex containing a coordinated SO(4)(2-) ion. Compounds 5-7 are prepared by treatment of Fe(O(2)CMe)(2) with Me-saoH(2) (5), Et-saoH(2) (6), Ph-saoH(2) (7) in the presence of H(3)tea (triethanolamine) in MeOH, and represent the largest nuclearity Fe(III) clusters containing salicyladoxime-based ligands, joining a surprisingly small family of characterised octanuclear Fe complexes. Variable temperature magnetic susceptibilty measurements of 1, 3 and 5-7 reveal all five complexes possess S = 0 spin ground states; 2 possesses an S = 1/2 spin ground state, while 4 has an S = 4 +/- 1 spin ground state.     

Rhodium pyrazolate complexes as potential CVD precursors

Reaction of 3,5-(CF(3))(2)PzLi with [Rh(μ-Cl)(η(2)-C(2)H(4))(2)](2) or [Rh(μ-Cl)(PMe(3))(2)](2) in Et(2)O gave the dinuclear complexes [Rh(η(2)-C(2)H(4))(2)(μ-3,5-(CF(3))(2)-Pz)](2) (1) and [Rh(2)(μ-Cl)(μ-3,5-(CF(3))(2)-Pz) (PMe(3))(4)] (2) respectively (3,5-(CF(3))(2)Pz = bis-trifluoromethyl pyrazolate). Reaction of PMe(3) with [Rh(COD)(μ-3,5-(CF(3))(2)-Pz)](2) in toluene gave [Rh(3,5-(CF(3))(2)-Pz)(PMe(3))(3)] (3). Reaction of 1 and 3 in toluene (1?:?4) gave moderate yields of the dinuclear complex [Rh(PMe(3))(2)(μ-3,5-(CF(3))(2)-Pz)](2) (4). Reaction of 3,5-(CF(3))(2)PzLi with [Rh(PMe(3))(4)]Cl in Et(2)O gave the ionic complex [Rh(PMe(3))(4)][3,5-(CF(3))(2)-Pz] (5). Two of the complexes, 1 and 3, were studied for use as CVD precursors. Polycrystalline thin films of rhodium (fcc-Rh) and metastable-amorphous films of rhodium phosphide (Rh(2)P) were grown from 1 and 3 respectively at 170 and 130 °C, 0.3 mmHg in a hot wall reactor using Ar as the carrier gas (5 cc min(-1)). Thin films of amorphous rhodium and rhodium phosphide (Rh(2)P) were grown from 1 and 3 at 170 and 130 °C respectively at 0.3 mmHg in a hot wall reactor using H(2) as the carrier gas (7 cc min(-1)).     

Reactivity of alkynes containing alpha-hydrogen atoms with a triruthenium hydrido carbonyl cluster: alkenyl versus allyl cluster derivatives

The reactions of the hydrido-triruthenium cluster complex [Ru3(mu-H)(mu3-kappa(2)-HNNMe2)(CO)9] (1; H2NNMe2 = 1,1-dimethylhydrazine) with alkynes that have alpha-hydrogen atoms give trinuclear derivatives containing edge-bridging allyl or face-capping alkenyl ligands. Under mild conditions (THF, 70 degrees C) the isolated products are as follows: [Ru3(mu3-kappa(2)-HNNMe2)(mu-kappa(3)-1-syn-Me-3-anti-EtC3H3)(mu-CO)2(CO)6] (2) and [Ru3(mu3-kappa(2)-HNNMe2)(mu-kappa(3)-1-syn-Me-3-syn-EtC3H3)(mu-CO)2(CO)6] (3) from 3-hexyne; [Ru3(mu3-kappa(2)-HNNMe2)(mu-kappa(3)-3-anti-PhC3H4)(mu-CO)2(CO)6] (4), [Ru3(mu3-kappa(2)-HNNMe2)(mu-kappa(2)-MeCCHPh)(mu-CO)2(CO)6] (5) and [Ru3(mu3-kappa(2)-HNNMe2)(mu3-kappa(2)-PhCCHMe)(mu-CO)2(CO)6] (6) from 1-phenyl-1-propyne; [Ru3(mu3-kappa(2)-HNNMe2)(mu-kappa(2)-3-anti-PrC3H4)(mu-CO)2(CO)6] (7), [Ru3(mu3-kappa(2)-HNNMe2)(mu3-kappa(2)-BuCCH2)(mu-CO)2(CO)6] (8), and [Ru3(mu3-kappa(2)-HNNMe2)(mu3-kappa(2)-HCCHBu)(mu-CO)2(CO)6] (9) from 1-hexyne; [Ru3(mu3-kappa(2)-HNNMe2)(mu3-kappa(2)-HOH2CCCH2)(mu-CO)2(CO)6] (10) from propargyl alcohol; and [Ru3(mu3-kappa(2)-HNNMe2)(mu3-kappa(2)-MeOCH2CCH2)(mu-CO)2(CO)6] (11) from 3-methoxy-1-propyne. The regioselectivity of these reactions depends upon the nature of the alkyne reagent, which affects considerably the kinetic barriers of important reaction steps and the stability of the final products. It has been established that the face-capped alkenyl derivatives are not precursors to the allyl products, which are formed via edge-bridged alkenyl intermediates. At higher temperature (toluene, 110 degrees C), the complexes that have allyl ligands with an anti substituent are isomerized into allyl derivatives with that substituent in the syn position, for example, 4 into [Ru3(mu3-kappa(2)-HNNMe2)(mu-kappa(3)-3-syn-PhC3H4)(mu-CO)2(CO)6] (14). The diene complex [Ru3(mu-H)(mu3-kappa(2)-HNNMe2)(mu-kappa(4)-trans-EtC4H5)(CO)7] (13) has been obtained from the thermolysis of compounds 2 and 7 at 110 degrees C (3 and [Ru3(mu3-kappa(2)-HNNMe2)(mu-kappa(2)-3-syn-PrC3H4)(mu-CO)2(CO)6] (12) are also formed in these reactions). A DFT theoretical study has allowed a comparison of the thermodynamic stabilities of isomeric compounds and has helped rationalize the experimental results. Mechanistic proposals for the synthesis of the allyl complexes and their isomerization processes are also provided.     

Mononuclear and dinuclear molybdenum and tungsten complexes of p-tert-butyltetrathiacalix[4]arene and p-tert-butyltetrasulfonylcalix[4]arene: facile cleavage of the calixarene ligand framework by nickel

The reactivity of p-tert-butyltetrathiacalix[4]arene, [S4CalixBut(OH)4], and p-tert-butyltetrasulfonylcalix[4]arene, [(SO2)4CalixBut(OH)4], toward Mo(PMe3)5H2, Mo(PMe3)6, and W(PMe3)4(eta2-CH2PMe2)H has been used to synthesize a series of mononuclear molybdenum and tungsten calixarene compounds that feature both coordinatively saturated and unsaturated metal centers, such as [S4CalixBut(OH)2(O)2]M(PMe3)3H2 (M = Mo, W), [(SO2)4CalixBut(OH)2(O)2]M(PMe3)3H2, [S4CalixBut(OH)2(O)2]Mo(PMe3)3, [(SO2)4CalixBut(OH)2(O)2]Mo(PMe3)3, and [(SO2)4CalixBut(OH)(O)3]M(PMe3)3H. Comparison with the related {[CalixBut(OH)2(O)2]M} complexes indicates that the chemistry of the system is strongly influenced by the nature of the calixarene linker, that is, CH2, S, and SO2. For example, in contrast to the methylene-bridged calixarene system, the thiacalixarene and sulfonylcalixarene systems readily coordinate a second metal center to form homo- and heterodinuclear complexes, namely {[S4CalixBut(O)4]}[M(PMe3)3H2]2, {[(SO2)4CalixBut(O)4]}[Mo(PMe3)3H2]2 and {[S4CalixBut(O)4]}[Mo(PMe3)3H2][W(PMe3)3H2]. Of most interest, incorporation of nickel into [S4CalixBut(OH)2(O)2]M(PMe3)3H2 using Ni(PMe3)4 results in cleavage of a C- bond to give [(SArButOH)(SArButO)3][M(PMe3)3H2][Ni(PMe3)2], an observation that is of relevance to the role that nickel plays in hydrodesulfurization catalysis.     

Dehydration reaction of hydroxyl substituted alkenes and alkynes on the Ru(2)S(2) complex

A variety of inter- and intramolecular dehydration was found in the reactions of [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)(mu-S(2))](CF(3)SO(3))(4) (1) with hydroxyl substituted alkenes and alkynes. Treatment of 1 with allyl alcohol gave a C(3)S(2) five-membered ring complex, [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)[mu-SCH(2)CH(2)CH(OCH(2)CH=CH(2))S]](CF(3)SO(3))(4) (2), via C-S bond formation after C-H bond activation and intermolecular dehydration. On the other hand, intramolecular dehydration was observed in the reaction of 1 with 3-buten-1-ol giving a C(4)S(2) six-membered ring complex, [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2) [mu-SCH(2)CH=CHCH(2)S]](CF(3)SO(3))(4) (3). Complex 1 reacts with 2-propyn-1-ol or 2-butyn-1-ol to give homocoupling products, [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)[mu-SCR=CHCH(OCH(2)C triple bond CR)S]](CF(3)SO(3))(4) (4: R = H, 5: R = CH(3)), via intermolecular dehydration. In the reaction with 2-propyn-1-ol, the intermediate complex having a hydroxyl group, [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)[mu-SCH=CHCH(OH)S]](CF(3)SO(3))(4) (6), was isolated, which further reacted with 2-propyn-1-ol and 2-butyn-1-ol to give 4 and a cross-coupling product, [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)[mu-SCH=CHCH(OCH(2)C triple bond CCH(3))S]](CF(3)SO(3))(4) (7), respectively. The reaction of 1 with diols, (HO)CHRC triple bond CCHR(OH), gave furyl complexes, [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)[mu-SSC=CROCR=CH]](CF(3)SO(3))(3) (8: R = H, 9: R = CH(3)) via intramolecular elimination of a H(2)O molecule and a H(+). Even though (HO)(H(3)C)(2)CC triple bond CC(CH(3))(2)(OH) does not have any propargylic C-H bond, it also reacts with 1 to give [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)[mu-SCH(2)C(=CH(2))C(=C=C(CH(3))(2))]S](CF(3)SO(3))(4) (10). In addition, the reaction of 1 with (CH(3)O)(H(3)C)(2)CC triple bond CC(CH(3))(2)(OCH(3)) gives [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(2)][mu-S=C(C(CH(3))(2)OCH(3))C=CC(CH(3))CH(2)S][Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)]](CF(3)SO(3))(4) (11), in which one molecule of CH(3)OH is eliminated, and the S-S bond is cleaved.     

p-tert-Butylcalix[4]arene complexes of molybdenum and tungsten: reactivity of the calixarene methylene C-H bond and the facile migration of the metal around the phenolic rim of the calixarene

p-tert-Butylcalix[4]arene, [CalixBut(OH)4], reacts with Mo(PMe3)6 and W(PMe3)4(eta2-CH2PMe2)H to yield compounds of composition {[CalixBut(OH)2(O)2]M(PMe3)3H2} which exhibit unprecedented use of a C-H bond of a calixarene methylene group as a binding functionality in the form of agostic and alkyl hydride derivatives. Thus, X-ray diffraction studies demonstrate that, in the solid state, the molybdenum complex [CalixBut(OH)2(O)2]Mo(PMe3)3H2 exists as an agostic derivative with a Mo...H-C interaction, whereas the tungsten complex exists as a metallated trihydride [Calix-HBut(OH)2(O)2]W(PMe3)3H3. Solution 1H NMR spectroscopic studies, however, provide evidence that [Calix-HBut(OH)2(O)2]W(PMe3)3H3 is in equilibrium with its agostic isomer [CalixBut(OH)2(O)2]W(PMe3)3H2. Dynamic NMR spectroscopy also indicates that the [M(PMe3)3H2] fragments of both the molybdenum and tungsten complexes [CalixBut(OH)2(O)2]M(PMe3)3H2 migrate rapidly around the phenolic rim of the calixarene on the NMR time scale, an observation that is in accord with incorporation of deuterium into the methylene endo positions upon treatment of the isomeric mixture of [CalixBut(OH)2(O)2]W(PMe3)3H2 and [Calix-HBut(OH)2(O)2]W(PMe3)3H3 with D2. Treatment of {[CalixBut(OH)2(O)2]W(PMe3)3H2} with Ph2C2 gives the alkylidene complex [CalixBut(O)4]W=C(Ph)Ar [Ar = PhCC(Ph)CH2Ph].     

Unusual equilibria involving group 4 amides, silyl complexes, and silyl anions via ligand exchange reactions

Silyl anion SiButPh2- (2) was found to substitute an amide ligand in Zr(NMe2)4 (3) to give the disilyl complex Zr(NMe2)3(SiButPh2)2- (1a) and Zr(NMe2)5- (1b) in THF. The reaction is reversible, and nucleophilic amide NMe2- attacks the Zr-SiButPh2 bonds in 1a or Zr(NMe2)3(SiButPh2) in the reverse reaction, leading to an unusual ligand exchange equilibrium 2 3 + 2 2 right harpoon over left harpoon 1a + 1b (eq 1). The silyl anion 2 selectively attacks the -N(SiMe3)2 ligand in Zr(NMe2)3[N(SiMe3)2] (6) to give 1a and N(SiMe3)2- (7). Reversible reaction occurs as well, where 7 selectively substitutes the silyl ligand in Zr(NMe2)3(SiButPh2)2- (1a) or Zr(NMe2)3(SiButPh2), giving the equilibrium 6 + 2 2 right harpoon over left harpoon 1a + 7 (eq 3). The thermodynamics of these equilibria has been studied: For eq 1, DeltaH degrees = -8.3(0.2) kcal/mol, DeltaS degrees = -23.3(0.9) eu, and DeltaG degrees 298K = -1.4(0.5) kcal/mol at 298 K; for eq 3, DeltaH degrees = -1.61(0.12) kcal/mol, DeltaS degrees = -2.6(0.5) eu, and DeltaG degrees 298K = -0.8(0.3) kcal/mol. In both equilibria, the enthalpy changes for the forward reactions outweigh the entropy changes, and therefore the substitutions of amide ligands in Zr(NMe2)4 (3) and Zr(NMe2)3[N(SiMe3)2] (6) to afford the disilyl complex 1a are thermodynamically favored. The following equilibria were also observed and studied: Zr(NMe2)3[N(SiMe3)2] (6) + Si(SiMe3)3- (9) right harpoon over left harpoon Zr(NMe2)3[Si(SiMe3)3] (10) + N(SiMe3)2- (7) and Zr(NMe2)4 (3) + 9 right harpoon over left harpoon 10 + Zr(NMe2)5- (1b).     

Synthesis and characterization of ionic liquids containing copper, manganese, or zinc coordination cations

Copper-, manganese-, and zinc-based ionic liquids (Cu{NH(2)CH(2)CH(2)OH}(6)[CH(3)(CH(2))(3)CH(C(2)H(5))CO(2)](2) (2), Cu{NH(CH(2)CH(2)OH)(2)}(6)[CH(3)(CH(2))(3)CH(C(2)H(5))CO(2)](2) (3A), Cu{NH(CH(2)CH(2)OH)(2)}(6)[CF(3)SO(3)](2) (3B), Cu{NH(CH(2)CH(2)OH)(2)}(6)[(CF(3)SO(2))(2)N](2) (3C), Mn{NH(CH(2)CH(2)OH)(2)}(6)[CF(3)SO(3)](2) (4), and Zn{NH(2)CH(2)CH(2)OH}(6)[CF(3)SO(3)](2) (5)) are synthesized in a single-step reaction. Infrared data suggest that ethanolamine preferentially coordinates to the metal center through the amine group in 2 and the hydroxyl group in 5. In addition, diethanolamine coordinates through the amine group in 3A, 3C, and 4 and the hydroxyl group in 3B. The compounds are viscous (>1000 cP) at room temperature, but two (3C and 4) display specific conductivities that are reasonably high for ionic liquids (>20 mS cm(-1)). All of the compounds display a glass transition (T(g)) below -50 °C. The cyclic voltammograms (CVs) of 2, 3A, 3B, and 3C display a single quasi-reversible wave associated with Cu(II)/Cu(I) reduction and re-oxidation while 5 shows a wave attributed to Zn(II)/Zn(0) reduction and stripping (re-oxidation). Compound 4 is the first in this new family of transition metal-based ionic liquids (MetILs) to display reversible Mn(II)/Mn(III) oxidation and re-reduction at 50 mV s(-1) using a glassy carbon working electrode.     

Reactions of tris(amino)phosphines with arylsulfonyl azides: product dependency on tris(amino)phosphine structure

The Staudinger reaction of N(CH2CH2NR)3P [R = Me (1), Pr (2)] with 1 equiv of N3SO2C6H4Me-4 gave the ionic phosphazides [N(CH2CH2NR)3PN][SO2C6H4Me-4] [R = Me (3), R = Pr (5a)], and the same reaction of 2 with N3SO2C6H2Me3-2,4,6 gave the corresponding aryl sulfinite 5b. On the other hand, the reaction of 1 with 0.5 equiv of N3SO2Ar (Ar = C6H4Me-4) furnished the novel ionic phosphazide [[N(CH2CH2NMe)3P]2(mu-N3)][SO2Ar] (6). Data that shed light on the mechanistic pathway leading to 3 were obtained by low temperature 31P NMR spectroscopy. A crystal and molecular structure analysis of the phosphazide sulfonate [N(CH2CH2NMe)3PN3][SO3C6H4Me-4] (4), obtained by atmospheric oxidation of 3, indicated an ionic structure, the cationic part of which is stabilized by a transannular P-N bond. A crystal and molecular structure analysis of 6 also indicated an ionic structure in which the cation features two untransannulated N(CH2CH2NMe)3P cages bridged by an azido group in an eta 1: mu: eta 1 fashion. The reaction of P(NMe2)3 with N3SO2Ar (Ar = C6H4Me-4) in a 1:0.5 molar ratio furnished [[(Me2N)3P]2(mu-N3)][SO2-Ar] (11) in quantitative yield. On the other hand, the same reaction involving a 1:1 molar ratio of P(NMe2)3 and N3SO2Ar produced a mixture of 11, [(Me2N)3PN3][SO2Ar] (12), and the iminophosphorane (Me2N)3P=NSO2Ar (10). In contrast, the bicyclic tris(amino)phosphines MeC(CH2NMe)3P (7) and O=P(CH2NMe)3P (8) reacted with N3SO2-Ar (Ar = C6H4Me-4) to give the iminophosphorane MeC(CH2NMe)3P=NSO2Ar (14) (structured by X-ray means) and O=P(CH2NMe)3P=NSO2Ar (16) via the intermediate phosphazides MeC(CH2NMe)3PN3SO2Ar (13) and O=P(CH2NMe)3PN3SO2Ar (15), respectively. The variety of products obtained from the reactions of arylsulfonyl azides with proazaphosphatranes (1 and 2), acyclic P(NMe2)3, bicyclic tris(amino)phosphines 7 and 8 are rationalized in terms of steric and basicity variations among the phosphorus reagents.     

C-H cleavage and double alkyl additions to the disulfido ligand in dicyanido-bridged Ru2S2 complexes

Novel dicyanido-bridged dicationic RuIIISSRuIII complexes [{Ru(P(OCH3)3)2}2(mu-S2)(mu-X)2{mu-m-C6H4(CH2CN)2}](CF3SO3)2 (4, X=Cl, Br) were synthesized by the abstraction of the two terminal halide ions of [{RuX(P(OCH3)3)2}2(mu-S2)(mu-X)2] (1, X=Cl, Br) followed by treatment with m-xylylenedicyanide. 4 reacted with 2,3-dimethylbutadiene to give the C4S2 ring-bridged complex [{Ru(P(OCH3)3)2}2{mu-SCH2C(CH3)=C(CH3)CH2S}(mu-X)2{mu-m-C6H4(CH2CN)2}](CF3SO3)2 (6, X=Cl, Br). In addition, 4 reacted with 1-alkenes in CH3OH to give alkenyl disulfide complexes [{Ru(P(OCH3)3)2}2{mu-SS(CH2C=CHR)}(mu-Cl)2{mu-m-C6H4(CH2CN)2}](CF3SO3) (7: R=CH2CH3, 9: R=CH2CH2CH3) and alkenyl methyl disulfide complexes [{Ru(P(OCH3)3)2}2{mu-S(CH3)S(CH2C=HR)}(mu-Cl)2{mu-m-C6H4(CH2CN)2}](CF3SO3)2 (8: R=CH2CH3, 10: R=CH2CH2CH3) via the activation of an allylic C-H bond followed by the elimination of H+ or condensation with CH3OH. Additionally, the reaction of 4 with 3-penten-1-ol gave [{Ru(P(OCH3)3)2}2{mu-SS(CH2C=CHCH2OH)}(mu-Cl)2{mu-m-C6H4(CH2CN)2}](CF3SO3) (11) via the elimination of H+ and [{Ru(P(OCH3)3)2}2(mu-SCH2CH=CHCH2S)(mu-Cl)2{mu-m-C6H4(CH2CN)2}](CF3SO3)2 (12) via the intramolecular elimination of a H2O molecule. 12 was exclusively obtained from the reaction of 4 with 4-bromo-1-butene.     

Methyl Tin(IV) derivatives of HOTeF(5) and HN(SO(2)CF(3))(2): a solution multinuclear NMR study and the X-ray crystal structures of (CH(3))(2)SnCl(OTeF(5)) and [(CH(3))(3)Sn(H(2)O)(2)][N(SO(2)CF(3))(2)

The new tin(IV) species (CH(3))(2)SnCl(OTeF(5)) was prepared via either the solvolysis of (CH(3))(3)SnCl in HOTeF(5) or the reaction of (CH(3))(3)SnCl with ClOTeF(5). It was characterized by NMR and vibrational spectroscopy, mass spectrometry, and single crystal X-ray diffraction. (CH(3))(2)SnCl(OTeF(5)) crystallizes in the monoclinic space group P2(1)/n (a = 5.8204(8) A, b =10.782(1) A, c =15.493(2) A, beta = 91.958(2) degrees, V = 971.7(2) A(3), Z = 4). NMR spectroscopy of (CH(3))(3)SnX, prepared from excess Sn(CH(3))(4) and HX (X = OTeF(5) or N(SO(2)CF(3))(2)), revealed a tetracoordinate tin environment using (CH(3))(3)SnX as a neat liquid or in dichloromethane-d(2) (CD(2)Cl(2)) solutions. In acetone-d(6) and acetonitrile-d(3) (CD(3)CN) solutions, the tin atom in (CH(3))(3)SnOTeF(5) was found to extend its coordination number to five by adding one solvent molecule. In the strong donor solvent DMSO, the Sn-OTeF(5) bond is broken and the (CH(3))(3)Sn(O=S(CH(3))(2))(2)(+) cation and the OTeF(5)(-) anion are formed. (CH(3))(3)SnOTeF(5) and (CH(3))(3)SnN(SO(2)CF(3))(2) react differently with water. While the Te-F bonds in the OTeF(5) group of (CH(3))(3)SnOTeF(5) undergo complete hydrolysis that results in the formation of [(CH(3))(3)Sn(H(2)O)(2)](2)SiF(6), (CH(3))(3)SnN(SO(2)CF(3))(2) forms the stable hydrate salt [(CH(3))(3)Sn(H(2)O)(2)][N(SO(2)CF(3))(2)]. This salt crystallizes in the monoclinic space group P2(1)/c (a = 7.3072(1) A, b =13.4649(2) A, c =16.821(2) A, beta = 98.705(1) degrees, V = 1636.00(3) A(3), Z = 4) and was also characterized by NMR and vibrational spectroscopy.     

Tetranuclear clusters containing a CrIII-doped MnIII4O2 core: syntheses, structures, and magnetic properties

The oxidation of MnII carboxylates by (NBu4)Cr2O7 in the presence of different phosphonic acids and chelating ligands results in six CrIII-doped tetranuclear manganese clusters formulated [Mn3CrO2(O2CCH3)4(O3PC5H4N)2(bpy)2] (1), [Mn3CrO2(O2CCH3)4(O3PC5H4N)2(phen)2] (2), [Mn3CrO2(O2CPh)4(O3PC5H4NO)2(phen)2] (3), [Mn3CrO2(O2CPh)4(O3PC6H11)2(bpy)2] (4), [Mn 3CrO2(O2CPh)4(O3PC6H11)2(phen) 2] (5), and [Mn3CrO2(O2CCH3)4(O3PC6H11)2(bpy)2] (6). Single-crystal X-ray analyses reveal that all the compounds contain similar [M4O2]8+ cores with the four metal sites arranged in planar topologies. The metal ions within the core are bridged by both carboxylate and phosphonate ligands. Temperature-dependent magnetic measurements show that in all cases dominant antiferromagnetic interactions are propagated between the metal centers. The ac magnetic measurements on compounds 5 and 6 reveal that both the in-phase and the out-of-phase signals are frequency dependent, characteristic of single-molecule magnet behaviors.     

Modulation of metal-metal separations in a series of Ag(I) and intensely blue photoluminescent Cu(I) NHC-bridged triangular clusters

A series of picolyl-substituted NHC-bridged triangular complexes of Ag(I) and Cu(I) were synthesized upon reaction of the corresponding ligand precursors, [Him(CH(2)py)(2)]BF(4) (1a), [Him(CH(2)py-3,4-(OMe)(2))(2)]BF(4) (1b), [Him(CH(2)py-3,5-Me(2)-4-OMe)(2)]BF(4) (1c), [Him(CH(2)py-6-COOMe)(2)]BF(4) (1d), and [H(S)im(CH(2)py)(2)]BF(4) (1e), with Ag(2)O and Cu(2)O, respectively. Complexes [Cu(3)(im(CH(2)py)(2))(3)](BF(4))(3) (2a), [Cu(3)(im(CH(2)py-3,4-(OMe)(2))(2))(3)](BF(4))(3) (2b), [Cu(3)(im(CH(2)py-3,5-Me(2)-4-OMe)(2))(3)](BF(4))(3), (2c), [Ag(3)(im(CH(2)py-3,4-(OMe)(2))(2))(3)](BF(4))(3), (3b), [Ag(3)(im(CH(2)py-3,5-Me(2)-4-OMe)(2))(3)](BF(4))(3) (3c), [Ag(3)(im(CH(2)py-6-COOMe)(2))(3)](BF(4))(3) (3d), and [Ag(3)((S)im(CH(2)py)(2))(3)](BF(4))(3) (3e) were easily prepared by this method. Complex 2e, [Cu(3)((S)im(CH(2)py)(2))(3)](BF(4))(3), was synthesized by a carbene-transfer reaction of 3e, [Ag(3)((S)im(CH(2)py)(2))(3)](BF(4))(3), with CuCl in acetonitrile. The ligand precursor 1d did not react with Cu(2)O. All complexes were fully characterized by NMR, UV-vis, and luminescence spectroscopies and high-resolution mass spectrometry. Complexes 2a-2c, 2e, and 3b-3e were additionally characterized by single-crystal X-ray diffraction. Each metal complex contains a nearly equilateral triangular M(3) core wrapped by three bridging NHC ligands. In 2a-2c and 2e, the Cu-Cu separations are short and range from 2.4907 to 2.5150 ?. In the corresponding Ag(I) system, the metal-metal separations range from 2.7226 to 2.8624 ?. The Cu(I)-containing species are intensely blue photoluminescent at room temperature both in solution and in the solid state. Upon UV excitation in CH(3)CN, complexes 2a-2c and 2e emit at 459, 427, 429, and 441 nm, whereas in the solid state, these bands move to 433, 429, 432, and 440 nm, respectively. As demonstrated by (1)H NMR spectroscopy, complexes 3b-3e are dynamic in solution and undergo a ligand dissociation process. Complexes 3b-3e are weakly photoemissive in the solid state.     

Solid state coordination chemistry of metal oxides: structural consequences of fluoride incorporation into the oxovanadium-copper-bisterpy-{O3P(CH2)nPO3}4- system, n= 1-5 (bisterpy = 2,2':4',4":2",2"'-quaterpyridyl-6', 6"-di-2-pyridine)

Hydrothermal reactions of a vanadate source, an appropriate Cu(II) source, bisterpy and an organodiphosphonate, H2O3P(CH2)nPO3H2(n= 1-5), in the presence of HF, yielded a family of materials of the type oxyfluorovanadium/copper-bisterpy/organodiphosphonate. Under similar reaction conditions, variations in diphosphonate tether length n provided the one-dimensional [{Cu2(bisterpy)}V2F2O2{HO3PCH2PO3}{O3PCH2PO3}](1) and [{Cu2(bisterpy)}V2F4O4{HO3P(CH2)2PO3H}](3), the two-dimensional [{Cu2(bisterpy)}V2F2O2(H2O)2{HO3P(CH2)2PO3}2] x 2H2O (2 x 2H2O), [{Cu2(bisterpy)(H2O2}V2F2O2{O3P(CH2)3PO3}{HO3P(CH2)3PO3H}(4) and [{Cu2(bisterpy)}V4F4O4(OH)(H2O){HO3P(CH2)5PO3}{O3P(CH2)5PO3}] x H2O (9 x H2O) and the three-dimensional [{Cu2(bisterpy)}3V8F6O17{HO3P(CH2)3PO3}4]0.8H2O (5 x 0.8H2O), [{Cu2(bisterpy)}V4F2O6{O3P(CH2)4PO3}2](8) and [{Cu2(bisterpy)(H2O)}2V8F4O8(OH)4{HO3P(CH2)5PO3H}2{O3P(CH2)5PO)}3] x 4.8H2O (10 x 4.8H2O). In addition, two members of the oxovanadium/Cu2(bisterpy)/organodiphosphonate family [{Cu2(bisterpy)}V2O4{HO3P(CH2)3PO3}2](6) and [{Cu2(bisterpy)}3V4O8(OH)2{O3P(CH2)3PO3}2{HO3P(CH2)3PO3}2] x 5H2O (7 x 5H2O) cocrystallized from the reaction mixture which provided 5. The overall architectures reveal embedded substructures based on V/P/O(F) clusters, chains, networks, and frameworks. In contrast to the oxovanadium/Cu2(bisterpy)/ organodiphosphonate family, several of the materials of this study also exhibit the direct condensation of vanadium polyhedra to produce binuclear and/or tetranuclear building units.