Alan R. Cutler

Facile template synthesis of nickel(II) complexes of dibenzotetraaza[14]annulenes

Preparation des complexes. On constate que ceux avec des substituants sur les cycles benzene sont generalement plus solubles dans les solvants organiques que ceux substitues sur les cycles diimine. Spectres UV

Bimetallic activation of coordinated ligands. Reactions of the Lewis acid (η-C5H5)(CO)3Mo+ PF6− with organo-iron and -molybdenum η1-methoxymethyl and ethyl complexes

Abstract The organometallic Lewis acid Cp(CO) 3 Mo + PF 6 − reacts with organo-iron and -molybdenum methoxymethyl and ethyl complexes via methoxide and/or hydride abstraction. Thus, Cp(CO) 3 MoCH 2 OCH 3 and Cp(CO)(L)FeCH 2 OCH 3 (L = CO, PPh 3 ) produce the corresponding methoxymethylidene salts Mo or FeCHOCH 3 + and Mo or Fe methyl complexes as primary products, the latter resulting from hydride transfer to methylidene intermediates Mo or FeCH 2 + . Analogous ethyl complexes afford the μ-[η 2 - C,O ]propionyl compound [Cp(CO) 2 Mo] 2 C(O)CH 2 CH 3 + and the η 2 -ethylene salt Cp(CO)(PPh 3 )Fe(CH 2 CH 2 ) + as primary products.

The reactions of hydrosilanes with the methoxycarbonyl complexes Cp(L)(CO)MCO2Me(MFe, Ru; LCO,PPh3) and (L)(CO)xMCO2Me(MCo, Mn; LCO, PPh3; x = 3,4, with and without catalysis

The reactivity of selected organotransition metal methoxycarbonyl complexes towards hydrosilanes differs significantly from their acetyl analogs in that hydrosilation does not occur across the methoxycarbonyl ligand. Only hydrosilane/manganese carbonyl precatalyst systems that had proved to be more active towards the acetyl ligand on Cp(L)(CO)MC(O)CH3 (MFe, Ru; LCO,PPh3, PPh3) reacted with the methoxycarbonyl complexes Cp(CO)2MCO2CH3 (1, MFe; 2, MRu). These reactions involving PhSiH3/2–3% (PPh3)(CO)4MnC(O)CH3 for 1 and 2, or PhMe2SiH/2–3% (CO)5MnCH3 for 1 afforded their η4-cyclopentadiene compounds (η4-C5H6)M(CO)3 (MFe,Ru) plus methoxysilanes. Results with PhMe2SiD/3% (CO)5MnCH3 support exo deuteride transfer to the Cp ligand; a mechanism is proposed. The low reactivity of methoxycarbonyl complexes under hydrosilation catalysis conditions also is consistent with the inactivity of PhSiH3 or Ph2SiH2/Rh(PPh3)3Cl towards 1 or 2 and with the inertness of Cp(PPh3)(CO)FeCO2CH3 and Cp∗(CO)2FeCO2CH3 under all attempted hydrosilation conditions. This diminution of hydrosilane reactivity extends to cobalt and manganese carbonyl methoxycarbonyl complexes (L)(CO)xMCO2CH3 (3, MMn, x = 4, LCO; 4, MCo, x = 3, LPPh3; 5, MCo, x = 3, LCO). Although their acetyl analogs (L)(CO)xMC(O)CH3 are sensitive to hydrosilanes, both 3 and 4 are inert towards PhMe2SiH or Ph2SiH2. Treatment of 5 with PhMe2SiH released methyl formate and left the silyl complex (CO)4CoSiMe2Ph, a result that resembles the hydrogenation chemistry of 5.

Synthesis and carbonylation of some α-alkoxyalkyl cobalt complexes, [RCH(or′)CO(CO)3PPh3] (R = H, CH3; R′ = Me, Et)

Abstract Cobalt α-alkoxyalkyl compounds [ROCH2Co(CO)3PPh3] (R = Me, Et) and [CH3(EtO)CHCo(CO)3PPh3] have been synthesized and transformed to their acyl derivatives, [R′CH(OR)C(O)Co(CO)3PPh3] 9R′ = H, CH3), using 1 atm. of CO. The α-ethoxyethyl complex [CH3(EtO)CHCo(CO)3PPh3] was generated by treating the acetyl compound [CH3C(O)Co(CO)3PPh3] with triethyloxonium hexafluorophosphate in CH2Cl2 and then reducing with LiHBEt3. The thermal instability of the resulting [CH3(EtO) CHCo(CO)3PPh3] compound precluded its full characterization, although it transformed into its acyl derivative in 82% isolated yield. The ethoxycarbene intermediate [CH3(EtO)C=Co(CO)3PPh3]+PF6−, the two alkoxymethyl complexes and the three acyl complexes have been characterized by elemental analysis and IR and NMR (1H, 13C, 31P) spectroscopy. Attempts to convert the α-alkoxyacyl complex [ROCH2C(O)Co(CO)3PPh3] and [CH3(EtO)CHC(O)Co(CO)3PPh3] into their alkoxycarbene compounds with a variety of alkylating agents instead afforded [CO(CO)3(PPh3)2]+.

Carbon dioxide activation as an η1-C metallocarboxylate: metallocarboxylate ester derivatives as a C1 template in co-ordinated ligand reactions

In tetrahydrofuran the reaction between Fp2Mg [Fp = Fe(CO)2(η-C5H5)] and CO2 gives the symmetrical metallocarboxylate (FpCO2)2Mg, which can be alkylated to give the ester FpCO2Me; its activated ester FpC(OMe)2+ serves as a C1 template for reduction to FpCH2OMe.

Reactions of carbon disulfide and carbon dioxide adducts (η-C5H5)(CO)2FeCX2− with organoiron electrophiles

Abstract Reactions of FpCS2−K+ (1) and FpCO2−Na+ (and Li+) (2) (Fp = η5-C5H5)(CO)2Fe) with organoiron electrophiles FpX (X = I, OSO2CF3, HgCl), (η5-C5H5)L(CO)FeI (L = P(OPh3), PPh3), and (η5-C5H5)(CO)Fe(CH3CN)2+PF6− are contrasted. Treatment of the CS2 adduct 1 with the bis-acetonitrile salt gives the η(η1-C: η2-S,S′)-CS2 complex FpC (S)SF e(CO)Cp, (4). Photolysis of the known η(η1-C: η1-S)-CS2 compound FpC(S)SFp (3) only generates traces of 4, in contrast. Treating the CO2 adduct 2 with the iron electrophiles Cp(L)(CO)FeI affords Fp2, with only trace amounts of FpFe(CO)(L)Cp (for L = PPh3 and P(OPh)3) evident. No η(η1-C: η1-O) bimetallocarboxylate intermediates FpC(O)OFe(L)(CO)Cp are detected. In contrast, Fp−Na+ upon treatment with (η5-C5H5)L(CO)FeI gives 1/1 mixtures of Fp2 and FpFe(CO)(L)Cp (for L = PPh3 and P(OPh)3). The bisacetonitrile electrophile and 2 afford initially the mixed dimer FpFe(CH3CN)(CO)-Cp, which degrades to Fp2 at room temperature. Organic carboxylates RCO2−M+ (R = Ph, CH2Ph, and t-Bu; M+ = Li+, Na+, K+) do not react with (η5-C5H5)(CO)Fe(CH3CN)2+; and photolysis of Fp(acetate) produces only Fp2, not an (η2-O,O′) acetate complex (η5-C5H5)(CO)Fe OC(O) CH3.

Copper(I) as a phosphine abstractor from (η-C5H5)(CO)(PPh3)FeCOCH3

Abstract The CuI complex Cu(CH3CN)4+PF6− chemoselectively abstracts phosphine from Cp(CO)(PPh3FeCOCH3 and produces Cp(CO)2FeCH3 in good yield. No evidence for electrophilic CuI coordinating the acetyl ligand on Cp(CO)(L)FeCOCH3 (L = CO, PPh3), however, was obtained Reactions of CuI and Cp(CO)(PPh3)FeCH3, with and without the presence of CO, also were examined. With CO, this methyl complex first gives its acetyl derivative Cp(CO)(PPh3)FeCOCH3 (1 atm CO in CH2Cl2 solution, 5 min), and after excess CO is removed (it otherwise blocks further reaction), Cp(CO)2FeCH3 forms.

Synthesis and solution dynamics of [Cp(CO)2Fe]2(CH=CH2)+BF4−, a μ-(η1:η2) vinyl complex not containing a metal-metal bond

Abstract Treatment of FpCHCH2 with the Lewis acid precursor Fp(THF)+BF4− affords the stable, fully characterized μ(η1:η2) vinyl complex (Fp-CHCH2)Fp+BF4− (3) [Fp  Fe(CO)2(η5-C5H5)]. Its IR and 1H, 13C NMR spectral data are consistent with an unsymmetrical 3p-complex [as established for vinyl ether compounds Fp(CH2=CHOR)+] between Fp-CHCH2 and the second Fp group, in which positive charge is extensively delocalized over both iron centers. The spectroscopically distinct Fp centers interchange, although this μ-vinyl ligand oscillation is very slow on the NMR time scale at room temperature. Results of 1H NMR magnetization transfer studies (using both spin saturation transfer and inversion transfer experimental procedures with the Cp resonances) converge on a first-order exchange rate constant kAB = 0.045–0.049 s− at 25°C. The calculated ΔG‡ = 19.3 kcal/mol is 2–3 kcal/mol greater than the estimated minimum ΔG‡ value for the known μ-vinyl compound [Cp(CO)Fe]2(μ-CO)(μ-η1:η2-CHCH2+ (1) that retains an iron-iron bond.

Bimetallic acetyl complexes: (η5-indenyl)2(CO)3Fe2(COCH3)− and (η5-indenyl)(η5-Cp)(CO)3Fe2(COCH3)−: their role in a novel carbonylation reaction

Abstract Treating alkly(η5-indenyl) iron complexes In(CO)2FeR (R  CH3, CH2OCH3) with either nucleophilic metalate Cp(CO)2Fe−Na+ (CP  η5-C5H5) or In(CO)2Fe−Na+ affords stable bimetallic complexes In(CO)Fe (η-CO)2Fe(In)- (COCH3)−Na+ (3) and (In)(Cp)(CO)3Fe2(COR)−Na+ (4, R  CH3; 9, R  CH2OCH3). The fully characterized PPN+ salts 3 and 4 (PPN  Ph3PNPPh3) both retain cis-structures having terminal (η1) acyl ligands. Compound 4 exists as a 1 1 mixture of isomers corresponding to the acetyl group at alternate iron centers: results of 1H NMR magnetization transfer experiments further established that these isomers slowly equilibrate at room temperature. X-ray structural determination of 4PPN+ showed that it crystallizes as the isomer having the acetyl coordinated on the CpFe end. These binuclear acyl products readily fragment (1 atm CO, R′X) into mononuclear acyl products, Cp(CO)2FeCOCH3 and Cp(CO)2FeCOCH2-OCH3 from 4 and 9, respectively, and In(CO)2FeCOCH3 from 3. By-products include In(CO)2FeR′ (R′  CH3, CH3CH2, Ph3Sn) and, depending on the reaction conditions, binuclear vinylidene compounds. A reaction pathway is proposed that accounts (by invoking reversible η5/η3-In ligand shifts) for the regioselective cleavage and carbonylation of 4 and 9 to their mononuclear Cp(CO)2Fe-acyl products.

Preparation of Some Organoiron Alkoxycarbene Salts

Abstract Convenient preparations of the organoiron alkoxycarbene salts (C5H5)(CO)(L)FeC(OR)R′+PF6 − (L=CO, PPh3; R=CH3, CH2CH3; R′=CH3, Ph), using dialkoxycarbenium ions to alkylate the requisite organoiron acyl complexes, are described.