Synthesis of ruthenium(II) complexes of tetradentate bis(N-pyridylimidazolylidenyl)methane and their reactivities towards N- donors

A family of hexa-coordinated ruthenium(II) complexes of bis(N-pyridylimidazolylidenyl)methane (L) were prepared and structurally characterized. Carbene transfer reactions of [Ru(p-cymene)Cl(2)](2), [Ru(CO)(2)Cl(2)](n) and RuHCl(CO)(PPh(3))(3) with silver-NHC complexes in situ generated from [H(2)L](PF(6))(2) and Ag(2)O afforded [RuL(CH(3)CN)(2)](PF(6))(2) (1), [Ru(2)L(p-cymene)(2)Cl(2)](PF(6))(2) (2), [RuL(CO)(2)](PF(6))(2) (3) and [RuL(PPh(3))(2)](PF(6))(2) (4), respectively. The reactions of 1 towards several N- and P-donors were studied. The treatment of 1 with 1,10-phenanthroline resulted in the substitution of one pyridine and one acetonitrile molecule affording [RuL(phen)(CH(3)CN)](PF(6))(2) (5) as a mixture of two isomers. Reaction of 1,2-bis(diphenylphosphino)ethane (dppe) and 1 gave [RuL(dppe)(CH(3)CN)(2)](PF(6))(2) (7), in which two pyridines were substituted by a dppe ligand trans to two NHC groups. In contrast, reactions of 1 with ethane-1,2-diamine, propane-1,3-diamine and 3,5-dimethyl-1H-pyrazole led to the substitution of acetonitrile and subsequent N-H addition of the C≡N bond of the coordinated acetonitrile yielding [RuL(ethane-1,2-diamine)(N-(2-aminoethyl)acetimidamide)](PF(6))(2) (8), [RuL(propane-1,3-diamine)(N-(3-aminopropyl)acetimidamide)](PF(6))(2) (9) and RuL(1-(3,5-dimethyl-1H-pyrazol-1-yl)ethanimine)(CH(3)CN)](PF(6))(2) (10), respectively.     

Isolation of (CO)1- and (CO2)1- radical complexes of rare earths via Ln(NR2)3/K reduction and [K2(18-crown-6)2]2+ oligomerization

Deep-blue solutions of Y(2+) formed from Y(NR(2))(3) (R = SiMe(3)) and excess potassium in the presence of 18-crown-6 at -45 °C under vacuum in diethyl ether react with CO at -78 °C to form colorless crystals of the (CO)(1-) radical complex, {[(R(2)N)(3)Y(μ-CO)(2)][K(2)(18-crown-6)(2)]}(n), 1. The polymeric structure contains trigonal bipyramidal [(R(2)N)(3)Y(μ-CO)(2)](2-) units with axial (CO)(1-) ligands linked by [K(2)(18-crown-6)(2)](2+) dications. Byproducts such as the ynediolate, [(R(2)N)(3)Y](2)(μ-OC≡CO){[K(18-crown-6)](2)(18-crown-6)}, 2, in which two (CO)(1-) anions are coupled to form (OC≡CO)(2-), and the insertion/rearrangement product, {(R(2)N)(2)Y[OC(═CH(2))Si(Me(2))NSiMe(3)]}[K(18-crown-6)], 3, are common in these reactions that give variable results depending on the specific reaction conditions. The CO reduction in the presence of THF forms a solvated variant of 2, the ynediolate [(R(2)N)(3)Y](2)(μ-OC≡CO)[K(18-crown-6)(THF)(2)](2), 2a. CO(2) reacts analogously with Y(2+) to form the (CO(2))(1-) radical complex, {[(R(2)N)(3)Y(μ-CO(2))(2)][K(2)(18-crown-6)(2)]}(n), 4, that has a structure similar to that of 1. Analogous (CO)(1-) and (OC≡CO)(2-) complexes of lutetium were isolated using Lu(NR(2))(3)/K/18-crown-6: {[(R(2)N)(3)Lu(μ-CO)(2)][K(2)(18-crown-6)(2)]}(n), 5, [(R(2)N)(3)Lu](2)(μ-OC≡CO){[K(18-crown-6)](2)(18-crown-6)}, 6, and [(R(2)N)(3)Lu](2)(μ-OC≡CO)[K(18-crown-6)(Et(2)O)(2)](2), 6a.     

High-pressure pulse-radiolysis study of the formation and decomposition of complexes with iron-carbon sigma bonds: mechanistic comparison for different metal centers

Volumes of activation for the formation and homolysis of the transient complexes (hedta)Fe(III)-CO(2)(2-) and (hedta)Fe(III)-CH(3)(-) (HOCH(2)CH(2)N(CH(2)CO(2-))CH(2)CH(2)N(CH(2)CO(2-))(2) = hedta) were determined using high-pressure pulse-radiolysis techniques. A comparison of the results with those for analogous complexes with other central transition-metal cations (M(n+)) and ligands (L) points out that (i) the reaction of M(n)L(m) with aliphatic radicals (R(*)) proceeds via an interchange ligand substitution mechanism, i.e. M(n)L(m) + R(*) --> L(m-1)M(n+1)-R + L, (ii) the homolysis of the metal-carbon bonds naturally follows the same mechanism, and (iii) the volume of activation for the homolysis reaction depends strongly on the nature of the central cation, i.e. larger for M(n+1) = Cr(III), Co(III), Ni(III) and smaller for Fe(III). The volume of activation for the reaction (hedta)Fe(III)-CO(2)(2-) + CO(2)(*-) + 2H(+) --> Fe(II)(hedta)(H(2)O)(-) + CO + CO(2) was measured, and the results enable a tentative proposal for the nature of the transition state of this interesting reaction.     

Diverse modes of reactivity of dialkyl azodicarboxylates with P(III) compounds: synthesis, structure, and reactivity of products other than the Morrison-Brunn-Huisgen intermediate in a Mitsunobu-type reaction

The reactivity of diethyl azodicarboxylate (DEAD)/diisopropyl azodicarboxylate (DIAD) with P(III) compounds bearing oxygen or nitrogen substituents is explored. Compounds with structures quite different from that of Morrison-Brunn-Huisgen intermediate R'(3)P(+)N(CO(2)R)N(-)(CO(2)R) (1), observed in the Mitsunobu reaction, have been established by using X-ray crystallography and NMR spectroscopy. Thus reactions with X(6-t-Bu-4-Me-C(6)H(2)O)(2)P-NH-t-Bu [X = S (8), CH(2) (9)] or XP(mu-N-t-Bu)(2)P-NH-t-Bu [X = Cl (14) or NH-t-Bu (15)] and DEAD/DIAD lead to phosphinimine-carbamate-type of products X[6-t-Bu-4-Me-C(6)H(2)O](2)P[N-t-Bu][N(CO(2)R)NH(CO(2)R)] [X = S, R = Et (16); X = CH(2), R = Et (17); X = CH(2), R = i-Pr (18)] or XP(mu-N-t-Bu)(2)P(N-t-Bu)[N-(CO(2)-i-Pr)-N(H)(CO(2)-i-Pr) [X = Cl (19), NH-t-Bu (20)]. Treatment of 19 with 2,2,2-trifluoroethanol afforded the product [(CF(3)CH(2)O)P(mu-N-t-Bu)(2)P(+)(NH-t-Bu)[N(CO(2)-i-Pr)(HNCO(2)-i-Pr)]][Cl(-)] (21) whose structure is close to one of the intermediates proposed in the Mitsunobu reaction. The isocyanate CH(2)(6-t-Bu-4-Me-C(6)H(2)O)(2)P-NCO (10) underwent 1,3-(P,C) cycloaddition with DEAD/DIAD to lead to CH(2)(6-t-Bu-4-Me-C(6)H(2)O)(2)P[N(CO(2)R)N(CO(2)R)-C(O)-N] [R = Et (22), i-Pr (23)]. Reaction of 22-23 with 1,1'-bi-2-naphthol or catechol leads to novel tetracoordinate CH(2)(6-t-Bu-4-Me-C(6)H(2)O)(2)P(2,2'-OC(10)H(6)-C(10)H(6)-OH)[NC(O)-(CO(2)R)NH(CO(2)R)] [R = Et (24), i-Pr (25)] or pentacoordinate CH(2)(6-t-Bu-4-Me-C(6)H(2)O)(2)P(1,2-O(2)C(6)H(4))[NHC(O)-N(CO(2)R)NH(CO(2)R)] [R = Et (26), i-Pr (27)] compounds in which the original NCO residue is retained; this mode of reactivity is quite different from that observed for the MBH betaine 1. In 27, the nitrogen, rather than the oxygen, occupies an apical position of the trigonal bipyramidal phosphorus violating the commonly assumed preference rules for apicophilicity. It is shown that the previously reported azide derivative 3, obtained from the reaction of 11 with DIAD, undergoes a Curtius-type rearrangement to lead to the fused cyclodiphosphazane [(CH(2)(6-t-Bu-4-Me-C(6)H(2)O)(2))P(OC(O-i-Pr)NN(CO(2)-i-Pr)N)](2) (28); this compound is in equilibrium with its monomeric form in solution at >300 K. Finally, reaction of S(6-t-Bu-4-Me-C(6)H(2)O)(2)P(OPh) (13) with DIAD gave the hexacoordinate compound S[6-t-Bu-4-Me-C(6)H(2)O](2)P(OPh)[N(CO(2)-i-Pr)NC(O-i-Pr)O] (30) with an intramolecular S-->P bond. X-ray crystallographic evidence for compounds 16, 19, 21, 22, 25, 27, 28, and 30 has been provided.     

Further characterization of Mitsunobu-type intermediates in the reaction of dialkyl azodicarboxylates with P(III) compounds

Structural characterization of compounds analogous to the proposed intermediates in the Mitsunobu esterification process is achieved by the combined use of NMR spectroscopy and X-ray diffractometric studies. The results show that compounds (t-BuNH)P(mu-N-t-Bu)(2)P[(N-t-Bu)(N-(CO(2)R)-N(H)(CO(2)R))] [R = Et (11), i-Pr (12)], obtained by treating [(t-Bu-NH)P-mu-N-t-Bu](2) (10) with diethylazodicarboxylate (DEAD) or diisopropylazodicarboxylate (DIAD), respectively, have a structure with the NH proton residing between the two nitrogen atoms ((P)N(t-Bu) and (P)N-N(CO(2)Et)); this is the tautomeric form of the expected betaine (t-BuNH)P(mu-N-t-Bu)(2)P(+)[(NH-t-Bu)(N-(CO(2)R)-N(-)(CO(2)R)]. Treatment of ClP(mu-N-t-Bu)(2)P[(N-t-Bu){N-(CO(2)-i-Pr)-N(H)(CO(2)-i-Pr)] (6) with 2,6-dicholorophenol affords (2,6-Cl(2)-C(6)H(3)-O)P(mu-N-t-Bu)(2)P(+)[(NH-t-Bu){N[(CO(2)i-Pr)(HNCO(2)i-Pr)]}](Cl(-))(2,6-Cl(2)-C(6)H(3)-OH) (14) that has a structure similar to that of (CF(3)CH(2)O)P(mu-N-t-Bu)(2)P(+)[(NH-t-Bu){N[(CO(2)i-Pr)(HNCO(2)i-Pr)]}](Cl(-)) (13), but with an additional hydrogen bonded phenol. Both of these have the protonated betaine structure analogous to that of Ph(3)P(+)N(CO(2)R)NH(CO(2)R)(R'CO(2))(-) (2) proposed in the Mitsunobu esterification. Two other compounds, (ArO)P(mu-N-t-Bu)(2)P(+)(NH-t-Bu){N(CO(2)i-Pr)(HNCO(2)i-Pr)}(Cl(-)) [Ar = 2,6-Me(2)C(6)H(3)O- (15) and 2-Me-6-t-Bu-C(6)H(3)-O- (16)], are also prepared by the same route. Although NMR tube reactions of 11 or 12 with tetrachlorocatechol, catechol, 2,2'-biphenol, and phenol revealed significant changes in the (31)P NMR spectra, attempted isolation of these products was not successful. On the basis of (31)P NMR spectra, the phosphonium salt structure (t-BuNH)P(mu-N-t-Bu)(2)P(+)[(HN-t-Bu){N-(CO(2)R)-N(H)(CO(2)R)](ArO(-)) is proposed for these. The weakly acidic propan-2-ol or water did not react with 11 or 12. Treatment of 12 with carboxylic acids/ p-toluenesulfonic acid gave the products (t-BuNH)P(mu-N-t-Bu)(2)P(+)[(HN-t-Bu){N-(CO(2)-i-Pr)-N(H)(CO(2)-i-Pr)](ArCO(2)(-)) [Ar = Ph (18), 4-Cl-C(6)H(4)CH(2) (19), 4-Br-C(6)H(4) (20), 4-NO(2)-C(6)H(4) (21)] and (t-BuNH)P(mu-N-t-Bu)(2)P(+)[(HN-t-Bu){N-(CO(2)-i-Pr)-N(H)(CO(2)-i-Pr)](4-CH(3)-C(6)H(4)SO(3)(-)) (22) that have essentially the same structure as 2. Compound 18 has additional stabilization by hydrogen bonding, as revealed by X-ray structure determination. Finally it is shown that the in situ generated (t-BuNH)P(mu-N-t-Bu)(2)P(+)[(HN-t-Bu){N-(CO(2)Et)-N(H)(CO(2)Et)](4-NO(2)-C(6)H(4)CO(2)(-)) can also effect Mitsunobu esterification. A comparison of the Ph(3)P-DIAD system with the analogous synthetically useful Ph(3)P-dimethyl acetylenedicarboxylate (DMAD) system is made.     

Ortho-hydroxyphenylhydrazo-β-diketones: tautomery, coordination ability, and catalytic activity of their copper(II) complexes toward oxidation of cyclohexane and benzylic alcohols

New hydrazone o-HO-phenylhydrazo-β-diketones (OHADB), R(1)NHN═CR(2)R(3) [R(1) = HO-2-C(6)H(4), R(2) = R(3) = COMe (H(2)L(1), 1), R(2)R(3) = COCH(2)C(Me)(2)CH(2)CO (H(2)L(2), 2), R(2) = COMe, R(3) = COOEt (H(2)L(4), 4); R(1) = HO-2-O(2)N-4-C(6)H(3), R(2)R(3) = COCH(2)C(Me)(2)CH(2)CO (H(2)L(3), 3), R(2) = COMe, R(3) = COOEt (H(2)L(5), 5), R(2)R(3) = COMe (H(2)L(6), 6A)], and their Cu(II) complexes [Cu(2)(CH(3)OH)(2)(μ-L(1))(2)] 7, [Cu(2)(H(2)O)(2)(μ-L(2))(2)] 8, [Cu(H(2)O)(L(3))] 9, [Cu(2)(μ-L(4))(2)](n) 10, [Cu(H(2)O)(L(5))] 11, [Cu(2)(H(2)O)(2)(μ-L(6))(2)] 12A and [Cu(H(2)O)(2)(L(6))] 12B were synthesized and fully characterized, namely, by X-ray analysis (4, 5, 7-12B). Reaction of 6A, Cu(NO(3))(2) and ethylenediamine (en) leads, via Schiff-base condensation, to [Cu{H(2)NCH(2)CH(2)N═C(Me)C(COMe)═NNC(6)H(3)-2-O-4-NO(2)}] (13), and reactions of 12A and 12B with en give the Schiff-base polymer [Cu{H(2)NCH(2)CH(2)N═C(Me)C(COMe)═NNC(6)H(3)-2-O-4-NO(2)}](n) 14. The dependence of the OHADB tautomeric equilibria on temperature, electronic properties of functional groups, and solvent polarity was studied. The OHADB from unsymmetrical β-diketones exist in solution as a mixture of enol-azo and hydrazo tautomeric forms, while in the solid state all the free and coordinated OHADB crystallize in the hydrazo form. The relative stabilities of various tautomers were studied by density functional theory (DFT). 7-14 show catalytic activities for peroxidative oxidation (in MeCN/H(2)O) of cyclohexane to cyclohexanol and cyclohexanone, for selective aerobic oxidation of benzyl alcohols to benzaldehydes in aq. solution, mediated by TEMPO radical, under mild conditions and for the MW-assisted solvent-free synthesis of ketones from secondary alcohols with tert-butylhydroperoxide as oxidant.     

Syntheses of 1-alkyl-1,2,4-triazoles and the formation of quaternary 1-alkyl-4-polyfluoroalkyl-1,2,4-triazolium salts leading to ionic liquids

1,2,4-triazole was alkylated (alkyl = methyl, butyl, heptyl, decyl) at N-1 in >90% isolated yields. The resulting 1-alkyl triazoles were quaternized at N-4 in >98% isolated yields using fluorinated alkyl halides with >98% isolated yields, under neat reaction conditions at 100-120 degrees C to form N1-CH(3)-N4-(CH(2))(2)C(m)F(2)(m)(+ 1)-triazolium (Taz) iodide (m = 1, 6), N1-C(4)H(9)-N4-(CH(2))(2)C(m)F(2)(m)(+ 1)-Taz iodide (m = 1, 4, 6), N1-C(7)H(15)-N4-(CH(2))(2)C(m)F(2)(m)(+ 1)-Taz iodide (m = 1, 4, 6), N1-C(10)H(21)-N4-(CH(2))(2)C(m)F(2)(m)(+1)-Taz iodide (m = 1, 4), and N1-C(n)H(2)(n )(+ 1)-N4-(CH(2))(2)F-Taz bromide (n = 4, 7, 10). Single-crystal X-ray analyses confirmed the structure of [1-CH(3)-4-CH(2)CH(2)CF(3)-Taz](+)I(-). It crystallized in the orthorhombic space group Pccn, and the unit cell dimensions were a = 13.8289(9) A, b = 17.3603(11) A, c = 9.0587(6) A (alpha = beta = gamma = 90 degrees ). Metathesis of these polyfluoroalkyl-substituted triazolium halides with other salts led to the formation of quaternary compounds, some of which comprise ionic liquids, namely, [R(R(f))-Taz](+)Y(-) (Y = NTf(2), BF(4), PF(6), and OTf), in good isolated yields without the need for further purification: N1-CH(3)-N4-(CH(2))(2)C(m)F(2)(m)( +) (1)-Taz Y (m = 1, 6; Y = NTf(2)), N1-C(4)H(9)-N4-(CH(2))(2)C(m)F(2)(m)(+ 1)-Taz Y (m = 1, 4, 6; Y = NTf(2)), N1- C(7)H(15)-N4-(CH(2))(2)C(m)F(2)(m)(+ 1)-Taz Y (m = 1, 4, 6; Y = NTf(2)), N1-C(10)H(21)-N4-(CH(2))(2)C(m)F(2)(m)(+1)-Taz Y (n = 1, 4; Y = NTf(2)), N1-C(n)H(2)(n )(+ 1)-N4-(CH(2))(2)F-Taz Y (n = 7, 10; Y = NTf(2)), N1-C(10)H(21)-N4-(CH(2))(2)F-TazY (Y = OTf), N1-C(7)H(15)-N4-(CH(2))(2)F-TazY (Y = BF(4)), N1-C(4)H(9)-N4-(CH(2))(2)C(m)F(2)(m) (+ 1)-Taz Y (m = 4, 6; Y = PF(6)), N1-C(7)H(15)-N4-(CH(2))(2)C(4)F(9)-Taz Y (Y = PF(6)), N1-C(4)H(9)-N4-(CH(2))(2)C(m)F(2)(m)(+ 1)-Taz Y (m = 4, 6; Y = OTf). All new compounds were characterized by (1)H, (19)F, and (13)C NMR and MS spectra and elemental analyses. T(g)s and T(m)s of ionic liquids were determined by DSC.     

Electron-transfer-catalyzed rearrangement of unsymmetrically substituted diiron dithiolate complexes related to the active site of the [FeFe]-hydrogenases

Novel asymmetrically substituted azadithiolate compounds [Fe2(CO)4(kappa2-dppe){micro-SCH2N(R)CH2S}] (R=iPr, 1a; CH2CH2OCH3, 1b; CH2C6H5, 1c) have been synthesized by treatment of [Fe2(CO)6(micro-adt)] [adt=SCH2N(R)CH2S, with R=iPr, CH2CH2OCH3, CH2C6H5] with dppe (dppe=Ph2PCH2CH2PPh2) in refluxing toluene in the presence of Me3NO. 1a-c have been characterized by single-crystal X-ray diffraction analyses. The electrochemical investigation of 1a-c and of [Fe2(CO)4(kappa2-dppe)(micro-pdt)] (1d) [pdt=S(CH2)3S] in MeCN- and THF-[NBu4][PF6] has demonstrated that the electrochemical reduction of 1a-d gives rise to an Electron-transfer-catalyzed (ETC) isomerization to the symmetrical isomers 2a-d where the dppe ligand bridges the iron centers. Compounds 2a-d were characterized by IR and NMR spectroscopy, elemental analysis, and X-ray crystallography for 2a.     

The synthesis, structure and dynamic behaviour of disubstituted alkenylphosphine derivatives of [Rh6(CO)16

A series of [Rh(6)(CO)(16)] substituted derivatives containing Ph(2)P(alkenyl) ligands has been synthesized starting from the [Rh(6)(CO)(16-x)(NCMe)(x)](x= 1, 2) clusters and Ph(2)P((CH(2))(n)CH=CH(2))(n= 2, 3) phosphines. It was shown that the terminal alkenyl substituents in these phosphines easily undergo isomerization in the coordination sphere of the hexarhodium complexes to give the allyl -CH(2)CH=C(H)R (R = Me and Et) fragments coordinated through the double bond of the rearranged organic moieties. The solid-state structure of two clusters, [Rh(6)(CO)(14)(mu2,kappa3-Ph(2)PCH(2)CH=C(H)CH(3))](4) and [Rh(6)(CO)(14)(mu2,kappa3-Ph(2)PCH(2)CH=C(H)CH(2)CH(3))](8), was established by X-ray crystallography. Solution structures of the products obtained were also characterized by IR and NMR ((1)H, (31)P, (1)H-(1)H COSY and (1)H-(1)H NOE) spectroscopy. It was shown that 4 and 8 exist in solution as mixtures of three isomers (A, B and C), which differ in the conformation of the coordinated allyl fragment. A similar (two species, A and B) equilibrium was found to occur in the solution of the [Rh(6)(CO)(14)(mu2,kappa3-Ph(2)PCH(2)CH=CH(2))](2) cluster. The dynamic behaviour of 2, 4 and 8[Rh(6)(CO)(14)(mu2,kappa3-Ph(2)PCH=CH(2))] has been studied using VT (31)P and (1)H-(1)H NOESY NMR spectroscopy, rate constants and activation parameters of the (A<-->B) isomerization processes were determined. It was shown that the most probable mechanism of this isomerization involves a dissociative [Rh6(CO)(14)(kappa1-Ph(2)P(alkenyl))] intermediate and re-coordination of the double bond to the same metal atom where the process started from. The conversion of the A and B species in and into the third isomer very likely occurs through the transfer of an allyl hydrogen atom onto the rhodium skeleton to give eventually cis conformation of the coordinated allyl fragment.     

Chiral bidentate aminophosphine ligands: synthesis, coordination chemistry and asymmetric catalysis

Chiral aminophosphines Ph2PN(R)(CH2)nN(R)PPh2 1-4 [n= 2, R = CH(CH3)(Ph) 1; n= 3, R = CH(CH2CH3)(Ph) 2, n= 2, R = CH(CH3)(1-naphthyl) 3; n= 2, R = CH(CH3)(C6H11) 4] were synthesized by the reaction of ClPPh2 with the appropriate easily accessible enantiopure amine building blocks. For compounds 1 and 2, the corresponding selenides 5 and 6 were prepared to determine the electronic character of the phosphine moieties. By reaction of 1 with either PdCl2(cod) or PdCl(CH3)(cod) the cis-complexes 7 and 8 were obtained. The molecular structure for complex 7, cis-[PdCl2(1)], was determined by X-ray crystallography. Reaction of PtCl2(cod) with 1 or 2 yielded the corresponding monomeric cis-isomers 9 and 10. The rhodium derivative [RhCl(CO)(1)] (11) was obtained as a mixture of cis and trans-isomers. Preliminary results in the rhodium catalyzed hydroformylation of styrene and vinyl acetate, with ee's up to 51% and high regioselectivities, showed the potential of these chiral aminophosphines for homogeneous catalysis.     

Synthesis of Fischer type-carbene complexes containing a coordinated thioimidate structural motif

This paper describes a tandem strategy to synthesize a series of new Fischer carbene complexes [(CO)(4)M[double bond, length as m-dash]C[N-(CH(2))(4)-]CH[double bond, length as m-dash]C(NRR')(SR'); M = Cr, W; R = Ar, R' = Me, -(CH(2))(2)-] with a thioimide or thiazoline fragment, in which the sulfur or nitrogen atom is coordinated to a metal center, depending on the nature of alkylating groups included as R'. We have trapped by protonation the proposed intermediate as the thioamide 12 [(CO)(5)W[double bond, length as m-dash]C[N-(CH(2))(4)-]CH(2)C(S)NHPh], which reveals the pathway of this reaction.     

Olefin metatheses in metal coordination spheres: versatile new strategies for the construction of novel monohapto or polyhapto cyclic, macrocyclic, polymacrocyclic, and bridging ligands

The broad applicability of the title reaction is established through studies of neutral and charged, coordinatively saturated and unsaturated, octahedral and square planar rhenium, platinum, rhodium, and tungsten complexes with cyclopentadienyl, phosphine, and thioether ligands which contain terminal olefins. Grubbs' catalyst, [Ru(=CHPh)(PCy3)2(Cl)2], is used at 2-9 mol% levels (0.0095-0.00042 M, CH2-Cl2). Key data are as follows: [(eta5-C5H4(CH2)6CH=CH2)Re(NO)(PPh3)-(CH3)], intermolecular metathesis (95 %); [(eta5-C5H5)Re(NO)(PPh3)(E(CH2CH=CH2)2)]+ TfO (E=S, PMe, PPh), formation of five-membered heterocycles (96-64%; crystal structure E = PMe); [(eta5-C5Me5)Re(NO)(PPh((CH2)6CH=CH2)2)(L)]n+ nBF4-(L/n = CO/1, Cl/0), intramolecular macrocyclization (94-89%; crystal structure L= Cl); fac-[(CO)3Re(Br)(PPh2(CH2)6CH=CH2)2] and cis-[(Cl)2Pt(PPh2(CH2)6CH=CH2)2], intramolecular macrocyclizations (80-71%; crystal structures of each and a hydrogenation product); cis-[(Cl)2Pt(S(R)(CH2)6CH= CH2)2], intra-/intermolecular macrocyclization (R=Et, 55%/24%; tBu, 72%/ <4%); trans-[(Cl)(L)M(PPh2(CH2)6CH=CH2)2] (M/L = Rh/CO, Pt/C6F5) intramolecular macrocyclization (90-83%; crystal structure of hydrogenation product, M=Pt); fac-[W(CO)3(PPh((CH2)6CH=CH2)2)3], intramolecular trimacrocyclization (83 %) to a complex mixture of triphosphine, diphosphine/ monophosphine, and tris(monophosphine) complexes, from which two isomers of the first type are crystallized. The macrocycle conformations, and basis for the high yields, are analyzed.     

Acrylonitrile insertion reactions of cationic palladium alkyl complexes

The reactions of acrylonitrile (AN) with "L(2)PdMe+" species were investigated; (L(2) = CH(2)(N-Me-imidazol-2-yl)(2) (a, bim), (p-tolyl)(3)CCH(N-Me-imidazol-2-yl)(2) (b, Tbim), CH(2)(5-Me-2-pyridyl)(2) (c, CH(2)py'(2)), 4,4'-Me(2)-2,2'-bipyridine (d), 4,4'-(t)Bu(2)-2,2'-bipyridine (e), (2,6-(i)Pr(2)-C(6)H(3))N=CMeCMe=N(2,6-(i)Pr(2)-C(6)H(3)) (f)). [L(2)PdMe(NMe(2)Ph)][B(C(6)F(5))(4)] (2a-c) and [{L(2)PdMe}(2)(mu-Cl)][B(C(6)F(5))(4)] (2d-f) react with AN to form N-bound adducts L(2)Pd(Me)(NCCH=CH(2))(+) (3a-f). 3a-e undergo 2,1 insertion to yield L(2)Pd{CH(CN)Et}+, which form aggregates [L(2)Pd{CH(CN)Et}](n)(n)(+) (n = 1-3, 4a-e) in which the Pd units are proposed to be linked by PdCHEtCN- - -Pd bridges. 3f does not insert AN at 23 degrees C. 4a-e were characterized by NMR, ESI-MS, IR and derivatization to L(2)Pd{CH(CN)Et}(PR(3))+ (R = Ph (5a-e), Me (6a-c)). 4a,b react with CO to form L(2)Pd{CH(CN)Et}(CO)+ (7a,b). 7a reacts with CO by slow reversible insertion to yield (bim)Pd{C(=O)CH(CN)Et}(CO)+ (8a). 4a-e do not react with ethylene. (Tbim)PdMe+ coordinates AN more weakly than ethylene, and AN insertion of 3b is slower than ethylene insertion of (Tbim)Pd(Me)(CH(2)=CH(2))(+) (10b). These results show that most important obstacles to insertion polymerization or copolymerization of AN using L(2)PdR+ catalysts are the tendency of L(2)Pd{CH(CN)CH(2)R}+ species to aggregate, which competes with monomer coordination, and the low insertion reactivity of L(2)Pd{CH(CN)CH(2)R}(substrate)+ species.     

Reactions of hydridoirida-β-diketones with amines or with 2-aminopyridines: formation of hydridoirida-β-ketoimines, PCN terdentate ligands, and acyl decarbonylation

The hydridoirida-β-diketone [IrHCl{(PPh(2)(o-C(6)H(4)CO))(2)H}] (1) reacts with benzylamine (C(6)H(5)CH(2)NH(2)) to give the hydridoirida-β-ketoimine [IrHCl{(PPh(2)(o-C(6)H(4)CO))(PPh(2)(o-C(6)H(4)CNCH(2)C(6)H(5)))H}] (2), stabilized by an intramolecular hydrogen bond. 2 reacts with water to undergo hydrolysis and amine coordination giving hydridodiacylamino [IrH(PPh(2)(o-C(6)H(4)CO))(2)(C(6)H(5)CH(2)NH(2))] (3). Cyclohexylamine or dimethylamine lead to hydridodiacylamino [IrH(PPh(2)(o-C(6)H(4)CO))(2)L] (4-5). In chlorinated solvents hydridodiacylamino complexes undergo exchange of hydride by chloride to afford [IrCl(PPh(2)(o-C(6)H(4)CO))(2)L] (6-9). The reaction of 1 with hydrazine (H(2)NNH(2)) gives hydridoirida-β-ketoimine [IrHCl{(PPh(2)(o-C(6)H(4)CO))(PPh(2)(o-C(6)H(4)CNNH(2)))H}] (10), fluxional in solution with values for ΔH(?) of 2.5 ± 0.3 kcal mol(-1) and for ΔS(?) of -32.9 ± 3 eu. A hydrolysis/imination sequence can be responsible for fluxionality. 2-Aminopyridines (RHNC(5)H(3)R'N) react with 1 to afford cis-[IrCl(PPh(2)(o-C(6)H(4)CO))(PPh(2)(o-C(6)H(4)CHNRC(5)H(3)R'N))] (R = R' = H (11), R = CH(3), R' = H (12), R = H, R' = CH(3) (13)) containing new terdentate PCN ligands in a facial disposition and cis phosphorus atoms as kinetic products. The formation of 11-13 requires imination of the hydroxycarbene moiety of 1, coordination of the nitrogen atom of pyridine to iridium, and iridium to carbon hydrogen transfer. In refluxing methanol, complexes 11-13 isomerize to afford the thermodynamic products 14-16 with trans phosphorus atoms. Chloride abstraction from complexes [IrCl(PPh(2)(o-C(6)H(4)CO))(PPh(2)(o-C(6)H(4)CHNRC(5)H(4)N))] (R = H or CH(3)) leads to decarbonylation of the acylphosphine chelating group to afford cationic complexes [Ir(CO)(PPh(2)(o-C(6)H(4)))(PPh(2)(o-C(6)H(4)CHNRC(5)H(4)N))]A, 17 (R = H, A = ClO(4)) and 18 (R = CH(3), A = BF(4)) as a cis/trans = 4:1 mixture of isomers. Single crystal X-ray diffraction analysis was performed on 6, 9, 13, and 14.     

Syntheses of novel exo and endo isomers of ansa-substituted fluorophosphazenes and their facile transformations into spiro isomers in the presence of fluoride ions

Reactions of the dilithiated diols RCH2P(S)(CH2OLi)2 [R = Fc (1), Ph (2) (Fc = ferrocenyl)] with N3P3F6 in equimolar ratios at -80 degrees C result exclusively in the formation of two structural isomers of ansa-substituted compounds, endo-RCH2P(S)(CH2O)2[P(F)N]2(F2PN) [R = Fc (3a), Ph (4a)] and exo-RCH2P(S)(CH2O)2[P(F)N]2(F2PN) [R = Fc (3b), Ph (4b)], which are separated by column chromatography. Increasing the reaction temperature to -40 degrees C results in more of the exo isomers 3b and 4b at the expense of the endo isomers. The formation of the ansa-substituted compounds is found to depend on the dilithiation of the diols, as a reaction of the silylated phosphine sulfide FcCH2P(S)(CH2OSiMe3)2 (5) with N3P3F6 in the presence of CsF does not yield either 3a or 3b but instead gives the spiro isomer [FcCH2P(S)(CH2O)2 PN](F2PN)2 (6) as the disubstitution product of N3P3F6. The ansa isomers 3a and 3b are transformed into the spiro compound 6 in the presence of catalytic amounts of CsF at room temperature in THF, while 4a and 4b are transformed into the spiro compound [PhCH2P(S)(CH2O)2PN](F2PN)2 (7) under similar conditions. The novel conversions of ansa-substituted phosphazenes into spirocyclic phosphazenes were monitored by time-dependent 31P NMR spectroscopy. The effect of temperature on a transformation was studied by carrying out reactions at various temperatures in the range from -60 to +33 degrees C for 3b. In addition, compounds 3a, 3b, 4a, and 6 were structurally characterized. In the case of the ansa compounds, the nitrogen atom flanked by the bridging phosphorus sites was found to deviate significantly from the plane defined by the five remaining atoms of the phosphazene ring.     

Reactions of [Et(4)N](3)[Sb{Fe(CO)(4)}(4)] with Alkyl Halides and Dihalides: Formation of the Alkyl- and the Dialkylantimony-Iron Carbonyl Complexes

The reactions of [Et(4)N](3)[Sb{Fe(CO)(4)}(4)] (1) with RX (R = Me, Et, n-Pr; X = I) in MeCN form the monoalkylated antimony complexes [Et(4)N](2)[RSb{Fe(CO)(4)}(3)] (R = Me, 2; R = Et, 4; R = n-Pr, 6) and the dialkylated antimony clusters [Et(4)N][R(2)Sb{Fe(CO)(4)}(2)] (R = Me, 3; R = Et, 5; R = n-Pr, 7), respectively. When [Et(4)N](3)[Sb{Fe(CO)(4)}(4)] reacts with i-PrI, only the monoalkylated antimony complex [Et(4)N](2)[i-PrSb{Fe(CO)(4)}(3)] (8) is obtained. The mixed dialkylantimony complex [Et(4)N][MeEtSb{Fe(CO)(4)}(2)] (9) also can be synthesized from the reaction of 2 with EtI. While the reaction with Br(CH(2))(2)Br produces [Et(4)N](2)[BrSb{Fe(CO)(4)}(3)] (10), treatment with Cl(CH(2))(3)Br forms the monoalkylated product [Et(4)N](2)[Cl(CH(2))(3)Sb{Fe(CO)(4)}(3)] (11) and a dialkylated novel antimony-iron complex [Et(4)N][{&mgr;-(CH(2))(3)}Sb{Fe(CO)(4)}(3)] (12). On the other hand, the reaction with Br(CH(2))(4)Br forms the monoalkylated antimony product and the dialkylated antimony complex [Et(4)N][{&mgr;-(CH(2))(4)}Sb{Fe(CO)(4)}(2)] (13). Complexes 2-13 are characterized by spectroscopic methods or/and X-ray analyses. On the basis of these analyses, the core of the monoalkyl clusters consists of a central antimony atom tetrahedrally bonded to one alkyl group and three Fe(CO)(4) fragments and the dialkyl products are structurally similar to the monoalkyl clusters, with the central antimony bonded to two alkyl groups and two Fe(CO)(4) moieties in each case. The dialkyl complex 3 crystallizes in the monoclinic space group P2(1)/c with a = 13.014(8) ?, b = 11.527(8) ?, c = 17.085(5) ?, beta = 105.04(3) degrees, V = 2475(2) ?(3), and Z = 4. Crystals of 12 are orthorhombic, of space group Pbca, with a = 14.791(4) ?, b = 15.555(4) ?, c = 27.118(8) ?, V = 6239(3) ?(3), and Z = 8. The anion of cluster 12 exhibits a central antimony atom bonded to three Fe(CO)(4) fragments with a -(CH(2))(3)- group bridging between the Sb atom and one Fe(CO)(4) fragment. This paper discusses the details of the reactions of [Et(4)N](3)[Sb{Fe(CO)(4)}(4)] with a series of alkyl halides and dihalides. These reactions basically proceed via a novel double-alkylation pathway, and this facile methodology can as well provide a convenient route to a series of alkylated antimony-iron carbonyl clusters.     

Tautomerization of methyldiazene to formaldehyde-hydrazone in ruthenium and osmium complexes

Mixed-ligand hydrazine complexes [M(CO)(RNHNH2)P4](BPh4)2 (1, 2) [M = Ru, Os; R = H, CH3, C6H5; P = P(OEt)3] with carbonyl and triethyl phosphite were prepared by allowing hydride [MH(CO)P4]BPh4 species to react first with HBF4.Et2O and then with hydrazines. Depending on the nature of the hydrazine ligand, the oxidation of [M(CO)(RNHNH2)P4](BPh4)2 derivatives with Pb(OAc)4 at -30 C gives acetate [M(kappa1-OCOCH3)(CO)P4]BPh4 (3a), phenyldiazene [M(CO)(C6H5N=NH)P4](BPh4)2 (3c, 4c), and methyldiazene [M(CO)(CH3N=NH)P4](BPh4)2 (3b, 4b) derivatives. Methyldiazene complexes 3b and 4b undergo base-catalyzed tautomerization of the CH3N=NH ligand to formaldehyde-hydrazone NH2N=CH2, giving the [M(CO)(NH2N=CH2)P4](BPh4)2 (5, 6) derivatives. Complexes 5 and 6 were characterized spectroscopically and by the X-ray crystal structure determination of the [Ru(CO)(NH2N=CH2)[P(OEt)3]4](BPh4)2 (5) derivative. Acetone-hydrazone [M(CO)[NH2N=C(CH3)2]P4](BPh4)2 (7, 8) complexes were also prepared by allowing hydrazine [M(CO)(NH2NH2)P4](BPh4)2 derivatives to react with acetone.     

Synthesis and properties of rhenium carbonyl complexes of alpha,alpha'-bis[(1-pyrenyl)pyrazol-1-yl]alkane ligands

The reaction between (1-acetyl)pyrene and dimethylformamide dimethylacetal followed by condensation of the resulting product mixture with hydrazine affords 3(5)-(1-pyrenyl)pyrazole (2) in good yield. The easily separable bis[(1-pyrenyl)pyrazole]methane derivatives CH(2)(3-pz(pyrene))(2) (3a, pz = pyrazolyl ring) and CH(2)(3-pz(pyrene))(5-pz(pyrene)) (3b) were prepared by metathetical reactions between pyrazole and CH(2)Cl(2), while CH((n)()Pr)(pz(pyrene))(2) (4) was prepared by transamination of 2 with butyraldehyde diethylacetal. Compounds 2-4 are luminescent under irradiation with UV light and have pyrenyl monomer-based emissions centered near 400 nm. Compounds 3a and 4 each react with Re(CO)(5)Br in a 1:1 molar ratio to form highly insoluble complexes Re(CO)(3)Br[(pz(pyrene))(2)CH(2)] (5) and Re(CO)(3)Br[(pz(pyrene))(2)CH((n)()Pr)] (6). Complex Re(CO)(3)Br[(pz)(2)CMe(2)] (7) was also prepared. X-ray structural studies of 6 show extensive pi-stacking of pyrenyl groups to form two-dimensional sheets. Pulsed field gradient spin-echo NMR (PGSE-NMR) experiments show that the complexes are monomeric in tetrachloroethane. Variable-temperature, difference NOE and 2-D NMR experiments demonstrate that isomers are present in solution that differ by restricted rotation about the pyrazolyl-pyrenyl bond. The pyrenyl-based emissions centered near 400 nm are quenched by complexation to the Re(CO)(3)Br moiety in 5 and 6.     

羰基铁-硫醇-三乙胺反应体系的研究, μ-酰基与μ-烯基铁硫配合物的合成系脱羰反应动力学

本文由反式巴豆酰氯与活性中间物[(μ-CO)(μ-R1S)Fe2(CO)6]ˉEt3N^+反应, 合成了两个新的μ-酰基铁硫配合物(μ-R1S)(μ-CH5CH=CHCO)Fe2(CO)6(R1=Et, Bu^t)和三个新的μ-烯基铁硫配合物(μ-R1S)(μ-CH3CH=CH)Fe2(CO)6(R1=Et, Bu^+, CH2=CHCH2), 此外还研究了μ-酰基配合物脱羰生成μ-烯基配合物的反应动力学, 证明为一级反应, 并求得在一定条件下的速率常数和半衰期。     

Syntheses of highly unsaturated isocyanides via organometallic pathways

The carbon carbon coupling reaction by nucleophilic attack of (CO)(5)Cr(CN-CF=CF(2)) 1 by lithium or Grignard compounds 2a-i yields the isocyanide complexes (CO)(5)Cr(CN-CF=CF-R) 3a-i (a R = CH=CH(2), b R = CH=CF(2), c R = C≡CH, d R = C≡C-SiMe(3), e R = C≡C-Ph, f R = C≡C-C(6)F(4)OMe, g R = C≡C-C(6)H(3)(CF(3))(2), h R = C(6)F(5), i R = C(6)H(3)(CF(3))(2)) as mixtures of E and Z isomers. The dinuclear complexes 5a-c are obtained from the reaction of 1 with the dilithio or dimagnesium compound 4a-c as the Z,Z-, E,Z- and E,E-isomers, respectively. (CO)(5)Cr(CN-CF=CF-C≡C-C≡C-CF=CF-NC)Cr(CO)(5)7 is obtained as a mixture of Z,Z-, Z,E- and E,E-isomers from (CO)(5)Cr(CN-CF=CF-C≡C-H 3d by Eglington-Glaser coupling. (CO)(5)Cr(CN-CF=CF-C≡C-CF=CF-NC)Cr(CO)(5)6 and (CO)(5)Cr(CN-CF=CF-C=C-C≡C-CF=CF-NC)Cr(CO)(5)7 react with octacarbonyldicobalt forming the cluster compounds Z,Z-[{η(2)-μ(2)-(CO)(5)Cr(CN-CF=CF-C≡C-CF=CF-NC)Cr(CO)(5)}Co(2)(CO)(6)] Z,Z-8, E,Z-[{η(2)-μ(2)-(CO)(5)Cr(CN-CF=CF-C≡C-CF=CF-NC)Cr(CO)(5)}Co(2)(CO)(6)] E,Z-8 and E,E-[{η(2)-μ(2)-(CO)(5)Cr(CN-CF=CF-C≡C-CF=CF-NC)Cr(CO)(5)}Co(2)(CO)(6)] E,E-8 and Z,Z-[{η(2)-μ(2)-(CO)(5)Cr(CN-CF=CF-C≡C-C≡C-CF=CF-NC)Cr(CO)(5)}{Co(2)(CO)(6)}(2)] Z,Z-9, E,Z-[{η(2)-μ(2)-(CO)(5)Cr(CN-CF=CF-C≡C-C≡C-CF=CF-NC)Cr(CO)(5)}{Co(2)(CO)(6)}(2)] E,Z-9 and E,E-[{η(2)-μ(2)-(CO)(5)Cr(CN-CF=CF-C≡C-C≡C-CF=CF-NC)Cr(CO)(5)}{Co(2)(CO)(6)}(2)] Z,Z-9, respectively. The crystal and molecular structures of E-3d, Z-3h, Z,Z-8, E,Z-8 and Z,Z-9 were elucidated by single-crystal X-ray crystallography.