Preparation and characterization of an isometallabenzene with the structure of a 1,2,4-cyclohexatriene

The elongated dihydrogen complex [Os{C6H4C(O) CH3}(eta2-H2)(H2O)(PiPr3)2]BF4 reacts with phenylacetylene and HBF4.OEt2 to give the unsaturated compound [Os{(E)-CH=CHPh}(CCPh)(CCH2Ph)(PiPr3)2]BF4 containing alkenyl, alkynyl, and carbyne ligands. The addition of sodium chloride to this compound leads to the cyclic allene Os{=C=C(Ph)CH(Ph)CH=C(CH2Ph)}Cl(PiPr3)2, which is the first isometallabenzene with the structure of a 1,2,4-cyclohexatriene.     

Two generalizable routes to terminal carbido complexes

Desulfurization of the thiocarbonyl ligand in square pyramidal [Ru(CS)Cl2(PCy3)2] (1-S) via sulfur atom abstraction using [Mo(H)(eta2-Me2CNAr)(N[i-Pr]Ar)2] forms [Ru(C)Cl2(PCy3)2] (1) cleanly over several hours in benzene; isolated yield is 55%. Complex 1 is also formed in 87% isolated yield upon reaction of [Ru(CHR)(PCy3)2Cl2] (R = p-C6H4Me, 2; Ph, 3) with vinyl acetate in dichloromethane. Complex 1-S is re-formed quantitatively from 1 upon treatment with elemental sulfur in CH2Cl2, but is prepared most conveniently by treatment of crude [Ru(CS)Cl2(PPh3)2(OH2)] with excess PCy3 in toluene. Nearly quantitative conversion of 1 to [Ru(CO)Cl2(PCy3)2] (1-O) occurs upon addition of dimethyldioxirane solution in acetone to 1 dissolved in CH2Cl2 at ca. -90 degrees C.     

New highly stable metallabenzenes via nucleophilic aromatic substitution reaction

Treatment of the ruthenabenzene [Ru{CHC(PPh(3))CHC(PPh(3))CH}Cl(2)(PPh(3))(2)]Cl (1) with excess 8-hydroxyquinoline in the presence of CH(3)COONa under air atmosphere produced the S(N)Ar product [(C(9) H(6)NO)Ru{CHC(PPh(3))CHC(PPh(3))C}(C(9)H(6)NO)(PPh(3))]Cl(2) (3). Ruthenabenzene 3 could be stable in the solution of weak alkali or weak acid. However, reaction of 3 with NaOH afforded a 7:1 mixture of ruthenabenzenes [(C(9)H(6)NO)Ru{CHC(PPh(3))CHCHC}(C(9)H(6)NO)(PPh(3))]Cl (4) and [(C(9)H(6)NO)Ru{CHCHCHC(PPh(3))C}(C(9)H(6)NO)(PPh(3))]Cl (5), presumably involving a P-C bond cleavage of the metallacycle. Complex 3 was also reactive to HCl, which results in a transformation of 3 to ruthenabenzene [Ru{CHC(PPh(3))CHC(PPh(3))C}Cl(2)(C(9)H(6)NO)(PPh(3))]Cl (6) in high yield. Thermal stability tests showed that ruthenabenzenes 4, 5, and 6 have remarkable thermal stability both in solid state and in solution under air atmosphere. Ruthenabenzenes 4 and 5 were found to be fluorescent in common solvents and have spectral behaviors comparable to those organic multicyclic compounds containing large π-extended systems.     

Ruthenium(II) and ruthenium(IV) complexes containing kappa1-P-, kappa2-P,O-, and kappa3-P,N,O-iminophosphorane-phosphine ligands Ph2PCH2P[=NP(=O)(OR)2]Ph2 (R = Et,Ph): synthesis,reactivity, theoretical studies,and catalytic activity in transfer hydrogenation of cyclohexanone

[(Ru(eta(6)-p-cymene)(mu-Cl)Cl)(2)] and [(Ru(eta(3):eta(3)-C(10)H(16))(mu-Cl)Cl)(2)] react with Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2) (R = Et (1a), Ph (1b)) affording complexes [Ru(eta(6)-p-cymene)Cl(2)(kappa(1)-P-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))] (R = Et (2a), Ph (2b)) and [Ru(eta(3):eta(3)-C(10)H(16))Cl(2)(kappa(1)-P-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))] (R = Et (6a), Ph (6b)). While treatment of 2a with 1 equiv of AgSbF(6) yields a mixture of [Ru(eta(6)-p-cymene)Cl(kappa(2)-P,O-Ph(2)PCH(2)P[=NP(=O)(OEt)(2)]Ph(2))][SbF(6)] (3a) and [Ru(eta(6)-p-cymene)Cl(kappa(2)-P,N-Ph(2)PCH(2)P[=NP(=O)(OEt)(2)]Ph(2))][SbF(6)] (4a), [Ru(eta(6)-p-cymene)Cl(kappa(2)-P,O-Ph(2)PCH(2)P[=NP(=O)(OPh)(2)]Ph(2))][SbF(6)] (3b) and [Ru(eta(3):eta(3)-C(10)H(16))Cl(kappa(2)-P,O-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))][SbF(6)] (R = Et (7a), Ph (7b)) are selectively formed from 2b and 6a,b. Complexes [Ru(eta(6)-p-cymene)(kappa(3)-P,N,O-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))][SbF(6)](2) (R = Et (5a), Ph (5b)) and [Ru(eta(3):eta(3)-C(10)H(16))(kappa(3)-P,N,O-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))][SbF(6)](2) (R = Et (8a), Ph (8b)) have been prepared using 2 equiv of AgSbF(6). The reactivity of 3-5a,b has been explored allowing the synthesis of [Ru(eta(6)-p-cymene)X(2)(kappa(1)-P-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))] (R = Et, Ph; X = Br, I, N(3), NCO (9-12a,b)). The catalytic activity of 2-8a,b in transfer hydrogenation of cyclohexanone, as well as theoretical calculations on the models [Ru(eta(6)-C(6)H(6))Cl(kappa(2)-P,N-H(2)PCH(2)P[=NP(=O)(OH)(2)]H(2))]+ and [Ru(eta(6)-C(6)H(6))Cl(kappa(2)-P,O-H(2)PCH(2)P[=NP(=O)(OH)(2)]H(2))]+, has been also studied.     

Dihydrogen activation by a diruthenium analogue of the Fe-only hydrogenase active site

The photochemical reaction of Ru2(S2C3H6)(CO)4(PCy3)2 (1) and H2 gives the dihydride Ru2(S2C3H6)(mu-H)(H)(CO)3(PCy3)2 (2). NMR and crystallographic studies reveal mutually trans basal phosphine ligands and both bridging and terminal hydrides. Ru2(S2C2H4)(CO)4(PCy3)2 behaves similarly. Other HX substrates undergo photoaddition to 1, affording Ru2(S2C3H6)(mu-H)(X)(CO)3(PCy3)2 for X = OTs (3a), Cl (3b), and SPh (3c). Treatment of Ru2(S2C3H6)(mu-H)(H)(CO)3(PCy3)2 with [H(OEt2)]BArF4 (ArF = B(C6H3-3,5-(CF3)2) in CD2Cl2 gives [Ru2(S2C3H6)(mu-H)(CO)3(PCy3)2(H2)]+ (4), which catalyzes H2-D2 exchange. The reaction of 2 with [D(OEt2)]BArF4 gave [Ru2(S2C3H6)(mu-H)(CO)3(PCy3)2(HD)]+ (JH-D = 31 Hz). These studies provide the first models for the Fe-only hydrogenases that bear dihydrogen and terminal hydrido ligands.     

Simply assembled and recyclable polymer-supported olefin metathesis catalysts

Polymer-supported ruthenium catalysts (PCy(3))(2)Ru(=C(H)Ph)Cl(2), (PCy(3))Ru(IMes)(=C(H)Ph)Cl(2), and (PCy(3))Ru(SIMes)(=C(H)Ph)Cl(2), where IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene and SIMes = 1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene, have been prepared and found to be effective "boomerang" catalysts for ring-closing metathesis. They are recyclable, show comparable or better reactivity than their homogeneous counterparts, tolerate functional groups, and perform very well with dienes and moderately well with highly hindered substrates.     

Ruthenium mediated C-H activation of 2-(arylazo)phenols: characterization of an intermediate and the final organoruthenium complex

Reaction of 2-(arylazo)phenols with [Ru(PPh(3))(2)(CO)(2)Cl(2)] affords a family of organometallic complexes of ruthenium(II) of type [Ru(PPh(3))(2)(CO)(CNO-R)], where the 2-(arylazo)phenolate ligand (CNO-R; R = OCH(3), CH(3), H, Cl, and NO(2)) is coordinated to the metal center as tridentate C,N,O-donor. Another group of intermediate complexes of type [Ru(PPh(3))(2)(CO)(NO-R)(H)] has also been isolated, where the 2-(arylazo)phenolate ligand (NO-R) is coordinated to the metal center as bidentate N,O-donor. Structures of the [Ru(PPh(3))(2)(CO)(NO-OCH(3))(H)] and [Ru(PPh(3))(2)(CO)(CNO-OCH(3))] complexes have been determined by X-ray crystallography. All the complexes are diamagnetic and show characteristic (1)H NMR signals and intense MLCT transitions in the visible region. Both the [Ru(PPh(3))(2)(CO)(NO-R)(H)] and [Ru(PPh(3))(2)(CO)(CNO-R)] complexes show two oxidative responses on the positive side of SCE.     

Ruthenium complexes with tetraphenylimidodiphosphinate: syntheses, structures, and applications to catalytic organic oxidation

Treatment of Ru(PPh3)3Cl2 with K(tpip) (tpip(-)=[N(Ph2PO)2](-)) afforded Ru(tpip)(PPh3)2Cl (1), which reacted with 4- t-Bu-C6H4CN, SO2(g), and NH 3(g) to give Ru(tpip)(PPh3)2Cl(4- t-BuC6H4CN) (2), Ru(tpip)(PPh3)2Cl(SO2) (3), and fac-[Ru(NH3)3(PPh3)2Cl][tpip] (4), respectively. Reaction of [Ru(CO)2Cl2] x with K(tpip) in refluxing tetrahydrofuran (THF) led to isolation of the K/Ru bimetallic compound K 2Ru2(tpip)4(CO)4Cl2 (5). Photolysis of cis-Ru(tpip) 2(NO)Cl in MeCN and wet CH 2Cl 2 afforded cis-Ru(tpip) 2(MeCN)Cl ( 6) and cis-Ru(tpip)2(H2O)Cl (7), respectively. Refluxing 6 in neat THF yielded Ru(tpip) 2(THF)Cl (8). Treatment of Ru(CHR)Cl2(PCy3)2 (Cy=cyclohexyl) with [Ag(tpip)] 4 afforded cis-Ru(tpip)2(CHR)(PCy3) [R=Ph (9), OEt (10)]. Complex 9 is capable of catalyzing oxidation of alcohols and olefins with N-methylmorpholine N-oxide and iodosylbenzene, respectively. The crystal structures of 2-7 and 9 were determined.     

Homobinuclear cyanide-bridged linkage isomers containing the redox-active unit [(micro-XY)Ru(CO)2L(o-O2C6Cl4)] (XY=CN or NC)

The salts [NEt4][Ru(CN)(CO)2L(o-O2C6Cl4)] {L=PPh3 or P(OPh)3}, which undergo one-electron oxidation at the catecholate ligand to give neutral semiquinone complexes [Ru(CN)(CO)2L(o-O2C6Cl4)], react with the dimers [{Ru(CO)2L(micro-o-O2C6Cl4)}2] {L=PPh3 or P(OPh)3} to give [NEt4][(o-O2C6Cl4)L(OC)2Ru(micro-CN)Ru(CO)2L'(o-O2C6Cl4)] {L or L'=PPh3 or P(OPh)3}. The cyanide-bridged binuclear anions are, in turn, reversibly oxidised to isolable neutral and cationic complexes [(o-O2C6Cl4)L(OC)2Ru(micro-CN)Ru(CO)2L'(o-O2C6Cl4)] and [(o-O2C6Cl4)L(OC)2Ru(micro-CN)Ru(CO)2L'(o-O2C6Cl4)]+ which contain one and two semiquinone ligands respectively. Structural studies on the redox pair [(o-O2C6Cl4)(Ph3P)(OC)2Ru(micro-CN)Ru(CO)2(PPh3)(o-O2C6Cl4)]- and [(o-O2C6Cl4)(Ph3P)(OC)2Ru(micro-CN)Ru(CO)2(PPh3)(o-O2C6Cl4)] confirm that the C-bound Ru(CO)2(o-O2C6Cl4) fragment is oxidised first. Uniquely, [(o-O2C6Cl4){(PhO)3P}(OC)2Ru(micro-CN)Ru(CO)2(PPh3)(o-O2C6Cl4)]- is oxidised first at the N-bound fragment, indicating that it is possible to control the site of electron transfer by tuning the co-ligands. Crystallisation of [(o-O2C6Cl4)(Ph3P)(OC)2Ru(micro-CN)Ru(CO)2{P(OPh)3}(o-O2C6Cl4)] resulted in the formation of an isomer in which the P(OPh)3 ligand is cis to the cyanide bridge, contrasting with the trans arrangement of the X-Ru-L fragment in all other complexes of the type RuX(CO)2L(o-O2C6Cl4).     

Formation of a dinuclear imido complex from the reaction of a ruthenium(VI) nitride with a ruthenium(II) hydride

The treatment of [Ru(L(OEt))(N)Cl(2)] (1; L(OEt)(-) = [Co(η(5)-C(5)H(5)){P(O)(OEt)(2)}(3)](-)) with Et(3)SiH affords [Ru(L(OEt))Cl(2)(NH(3))] (2), whereas that with [Ru(L(OEt))(H)(CO)(PPh(3))] (3) gives the dinuclear imido complex [(L(OEt))Cl(2)Ru(μ-NH)Ru(CO)(PPh(3))(L(OEt))] (4). The imido group in 4 binds to the two ruthenium atoms unsymmetrically with Ru-N distances of 1.818(6) and 1.952(6) ?. The reaction between 1 and 3 at 25 °C in a toluene solution is first order in both complexes with a second-order rate constant determined to be (7.2 ± 0.4) × 10(-5) M(-1) s(-1).     

Group 11 complexes containing the [C5(CN)5]- ligand; 'coordination-analogues' of molecular organometallic systems

The reactions of Na[C(5)(CN)(5)] (Na[1]) with group 11 phosphine complexes [(P)(n)MCl] (M = Cu, Ag, Au, P = Ph(3)P; M = Cu, P = dppe (Ph(2)PCH(2)CH(2)PPh(2))] give a range of compounds containing the pentacyanocyclopentadienide ligand, [C(5)(CN)(5)](-) (1). The new complexes [(Ph(3)P)(2)M{1}](2) [M = Cu (3); M = Ag (5)], [(Ph(3)P)(3)Ag{1}] (4), [(dppe)(3)Cu(2){1}(2)] (6) and [Au(PPh(3))(2)][1] (7) include the first complete series of group 11 complexes of any cyclopentadienide ligand to be structurally characterised.     

Amidoximes provide facile platinum(II)-mediated oxime-nitrile coupling

The nucleophilic addition of amidoximes R'C(NH(2))═NOH [R' = Me (2.Me), Ph (2.Ph)] to coordinated nitriles in the platinum(II) complexes trans-[PtCl(2)(RCN)(2)] [R = Et (1t.Et), Ph (1t.Ph), NMe(2) (1t.NMe(2))] and cis-[PtCl(2)(RCN)(2)] [R = Et (1c.Et), Ph (1c.Ph), NMe(2) (1c.NMe(2))] proceeds in a 1:1 molar ratio and leads to the monoaddition products trans-[PtCl(RCN){HN═C(R)ONC(R')NH(2)}]Cl [R = NMe(2); R' = Me ([3a]Cl), Ph ([3b]Cl)], cis-[PtCl(2){HN═C(R)ONC(R')NH(2)}] [R = NMe(2); R' = Me (4a), Ph (4b)], and trans/cis-[PtCl(2)(RCN){HN═C(R)ONC(R')NH(2)}] [R = Et; R' = Me (5a, 6a), Ph (5b, 6b); R = Ph; R' = Me (5c, 6c), Ph (5d, 6d), correspondingly]. If the nucleophilic addition proceeds in a 2:1 molar ratio, the reaction gives the bisaddition species trans/cis-[Pt{HN═C(R)ONC(R')NH(2)}(2)]Cl(2) [R = NMe(2); R' = Me ([7a]Cl(2), [8a]Cl(2)), Ph ([7b]Cl(2), [8b]Cl(2))] and trans/cis-[PtCl(2){HN═C(R)ONC(R')NH(2)}(2)] [R = Et; R' = Me (10a), Ph (9b, 10b); R = Ph; R' = Me (9c, 10c), Ph (9d, 10d), respectively]. The reaction of 1 equiv of the corresponding amidoxime and each of [3a]Cl, [3b]Cl, 5b-5d, and 6a-6d leads to [7a]Cl(2), [7b]Cl(2), 9b-9d, and 10a-10d. Open-chain bisaddition species 9b-9d and 10a-10d were transformed to corresponding chelated bisaddition complexes [7d](2+)-[7f](2+) and [8c](2+)-[8f](2+) by the addition of 2 equiv AgNO(3). All of the complexes synthesized bear nitrogen-bound O-iminoacylated amidoxime groups. The obtained complexes were characterized by elemental analyses, high-resolution ESI-MS, IR, and (1)H NMR techniques, while 4a, 4b, 5b, 6d, [7b](Cl)(2), [7d](SO(3)CF(3))(2), [8b](Cl)(2), [8f](NO(3))(2), 9b, and 10b were also characterized by single-crystal X-ray diffraction.     

Synthesis, characterization, and reactivity of Fe complexes containing cyclic diazadiphosphine ligands: the role of the pendant base in heterolytic cleavage of H2

The iron complexes CpFe(P(Ph)(2)N(Bn)(2))Cl (1-Cl), CpFe(P(Ph)(2)N(Ph)(2))Cl (2-Cl), and CpFe(P(Ph)(2)C(5))Cl (3-Cl)(where P(Ph)(2)N(Bn)(2) is 1,5-dibenzyl-1,5-diaza-3,7-diphenyl-3,7-diphosphacyclooctane, P(Ph)(2)N(Ph)(2) is 1,3,5,7-tetraphenyl-1,5-diaza-3,7-diphosphacyclooctane, and P(Ph)(2)C(5) is 1,4-diphenyl-1,4-diphosphacycloheptane) have been synthesized and characterized by NMR spectroscopy, electrochemical studies, and X-ray diffraction. These chloride derivatives are readily converted to the corresponding hydride complexes [CpFe(P(Ph)(2)N(Bn)(2))H (1-H), CpFe(P(Ph)(2)N(Ph)(2))H (2-H), CpFe(P(Ph)(2)C(5))H (3-H)] and H(2) complexes [CpFe(P(Ph)(2)N(Bn)(2))(H(2))]BAr(F)(4), [1-H(2)]BAr(F)(4), (where BAr(F)(4) is B[(3,5-(CF(3))(2)C(6)H(3))(4)](-)), [CpFe(P(Ph)(2)N(Ph)(2))(H(2))]BAr(F)(4), [2-H(2)]BAr(F)(4), and [CpFe(P(Ph)(2)C(5))(H(2))]BAr(F)(4), [3-H(2)]BAr(F)(4), as well as [CpFe(P(Ph)(2)N(Bn)(2))(CO)]BAr(F)(4), [1-CO]Cl. Structural studies are reported for [1-H(2)]BAr(F)(4), 1-H, 2-H, and [1-CO]Cl. The conformations adopted by the chelate rings of the P(Ph)(2)N(Bn)(2) ligand in the different complexes are determined by attractive or repulsive interactions between the sixth ligand of these pseudo-octahedral complexes and the pendant N atom of the ring adjacent to the sixth ligand. An example of an attractive interaction is the observation that the distance between the N atom of the pendant amine and the C atom of the coordinated CO ligand for [1-CO]BAr(F)(4) is 2.848 ?, considerably shorter than the sum of the van der Waals radii of N and C atoms. Studies of H/D exchange by the complexes [1-H(2)](+), [2-H(2)](+), and [3-H(2)](+) carried out using H(2) and D(2) indicate that the relatively rapid H/D exchange observed for [1-H(2)](+) and [2-H(2)](+) compared to [3-H(2)](+) is consistent with intramolecular heterolytic cleavage of H(2) mediated by the pendant amine. Computational studies indicate a low barrier for heterolytic cleavage of H(2). These mononuclear Fe(II) dihydrogen complexes containing pendant amines in the ligands mimic crucial features of the distal Fe site of the active site of the [FeFe]-hydrogenase required for H-H bond formation and cleavage.     

Primary and secondary phosphane complexes of metalloporphyrins: isolation, spectroscopy, and X-ray crystal structures of ruthenium and osmium porphyrins binding phenyl- or diphenylphosphane

[Ru(II)(por)(PH(n)Ph(3-n))2], [Os(II)(por)(CO)(PH(n)Ph(3-n))] (n=1, 2), and [Os(II)(F20-tpp){P(OH)Ph2}(PHPh2)] (F20-tpp=5,10,15,20-tetrakis(pentafluorophenyl)porphyrinato dianion) were prepared from the reaction of [M(II)(por)(CO)] (M=Ru, Os) or [Os(VI)(por)O2] with the respective primary/secondary phosphane and characterized by 1H NMR, 31P NMR, UV/Vis, and IR spectroscopy, mass spectrometry, and elemental analysis. The reaction of [Os(VI)(por)O2] with PHPh2 also gave minor amounts of [Os(II)(por){P(OH)Ph2}2]. [Ru(II)(F20-tpp)(PH2Ph)2] exhibits a remarkable stability toward air and shows a reversible metal-centered oxidation couple at E(1/2)=0.39 V versus [Cp2Fe](+/0) in the cyclic voltammogram. The structures of [Ru(II)(F20-tpp)(PH2Ph)2] x 2CH2Cl2, [Ru(II)(4-Cl-tpp)(PHPh2)2] x 2CH2Cl2 (4-Cl-tpp=5,10,15,20-tetrakis(p-chlorophenyl)porphyrinato dianion), [Ru(II)(F20-tpp)(PHPh2)2], and [Os(II)(F20-tpp){P(OH)Ph2}2] were determined by X-ray crystallography and feature Ru-P distances of 2.3397(11)-2.3609(9) A and an Os-P distance of 2.369(2) A.     

Vinyl and carbene ruthenium(II) complexes from hydridoruthenium(II) precursors

The reactions of the hydrido compounds [RuHCl(CO)(L)2][L = PiPr3 (1), PCy3 (2)] with HC(triple bond)CR (R = H, Ph, tBu) afforded by insertion of the alkyne into the Ru-H bond the corresponding vinyl complexes [RuCl(CHCHR)(CO)(L)2], 3-8, which upon protonation with HBF4 gave the cationic five-coordinated ruthenium carbenes [RuCl(CHCH2R)(CO)(L)2]BF4, 9-14. Subsequent reactions of the carbene complexes with PR3(R = Me, iPr) and CH3CN led either to deprotonation and re-generation of the vinyl compounds or to cleavage of the ruthenium-carbene bond and the formation of the six-coordinated complexes [RuCl(CO)(CH3CN)2(PiPr3)2]BF4, 17, and [RuH(CO)(CH3CN)2(PiPr3)2]X, 18a,b. The acetato derivative [RuH(2-O2CCH3)(CO)(PCy3)2], 19, also reacted with acetylene and phenylacetylene by insertion to yield the related vinyl complexes [Ru(CHCHR)(kappa2-O2CCH3)(CO)(PCy3)2], 20, 21, of which that with R = H was protonated with HBF4 to yield the corresponding cationic ruthenium carbene 22. With [RuHCl(H2)(PCy3)2], 25, as the starting material, the five-coordinated chloro(hydrido)ruthenium(II) compounds [RuHCl(PCy3)(dppf)], 26(dppf = [Fe(eta5-C5H4PPh2)2]), [RuHCl[Sb(CH2Ph)3](PCy3)2], 27, and [RuHCl(CH3CN)(PCy3)2], 30, were prepared. The reactions of 27 with HCCR (R = H, Ph) gave the hydrido(vinylidene) complexes [RuHCl(CCHR)(PCy3)2], 28 and 29, whereas treatment of 30 with HC(triple bond)CPh afforded the vinyl compound [RuCl(CHCHPh)(CH3CN)(PCy3)2], 31. The molecular structures of 11(R = tBu, L = PiPr3) and 26 were determined crystallographically.     

Stoichiometric and catalytic reactivity of the N-heterocyclic carbene ruthenium hydride complexes [Ru(NHC)(L)(CO)HCl] and [Ru(NHC)(L)(CO)H(eta2-BH4)] (L=NHC, PPh3)

Thermolysis of [Ru(AsPh3)3(CO)H2] with the N-aryl heterocyclic carbenes (NHCs) IMes (1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene), IPr (1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) or the adduct SIPr.(C6F5)H (SIPr=1,3-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazol-2-ylidene), followed by addition of CH2Cl2, affords the coordinatively unsaturated ruthenium hydride chloride complexes [Ru(NHC)2(CO)HCl] (NHC=IMes , IPr , SIPr ). These react with CO at room temperature to yield the corresponding 18-electron dicarbonyl complexes . Reduction of and [Ru(IMes)(PPh3)(CO)HCl] () with NaBH4 yields the isolable borohydride complexes [Ru(NHC)(L)(CO)H(eta2-BH4)] (, L=NHC, PPh3). Both the bis-IMes complex and the IMes-PPh3 species react with CO at low temperature to give the eta1-borohydride species [Ru(IMes)(L)(CO)2H(eta1-BH4)] (L=IMes , PPh3), which can be spectroscopically characterised. Upon warming to room temperature, further reaction with CO takes place to afford initially [Ru(IMes)(L)(CO)2H2] (L=IMes, L=PPh3) and, ultimately, [Ru(IMes)(L)(CO)3] (L=IMes , L=PPh3). Both and lose BH3 on addition of PMe2Ph to give [Ru(IMes)(L)(L')(CO)H2](L=L'=PMe2Ph; L=PPh3, L'=PMe2Ph). Compounds and have been tested as catalysts for the hydrogenation of aromatic ketones in the presence of (i)PrOH and H2. For the reduction of acetophenone, catalytic activity varies with the NHC present, decreasing in the order IPr>IMes>SIMes.     

Cyclopropenylidene carbene ligands in palladium catalysed coupling reactions: carbene ligand rotation and application to the Stille reaction

Reaction of [Pd(PPh(3))(4)] with 1,1-dichloro-2,3-diarylcyclopropenes gives complexes of the type cis-[PdCl(2)(PPh(3))(C(3)(Ar)(2))] (Ar = Ph 5, Mes 6). Reaction of [Pd(dba)(2)] with 1,1-dichloro-2,3-diarylcyclopropenes in benzene gave the corresponding binuclear palladium complexes trans-[PdCl(2)(C(3)(Ar)(2))](2) (Ar = Ph 7, p-(OMe)C(6)H(4)8, p-(F)C(6)H(4)9). Alternatively, when the reactions were performed in acetonitrile, the complexes trans-[PdCl(2)(NCMe)(C(3)(Ar)(2))] (Ar = Ph 10, p-(OMe)C(6)H(4)11 and p-(F)C(6)H(4)) 12) were isolated. Addition of phosphine ligands to the binuclear palladium complex 7 or acetonitrile adducts 11 and 12 gave complexes of the type cis-[PdCl(2)(PR(3))(C(3)(Ar)(2))] (Ar = Ph, R = Cy 13, Ar = p-(OMe)C(6)H(4), R = Ph 14, Ar = p-(F)C(6)H(4), R = Ph 15). Crystal structures of complexes 6·3.25CHCl(3), 10, 11·H(2)O and 12-15 are reported. DFT calculations of complexes 10-12 indicate the barrier to rotation about the carbene-palladium bond is very low, suggesting limited double bond character in these species. Complexes 5-9 were tested for catalytic activity in C-C coupling (Mizoroki-Heck, Suzuki-Miyaura and, for the first time, Stille reactions) and C-N coupling (Buchwald-Hartwig amination) showing excellent conversion with moderate to high selectivity.     

Group 6 imido complexes supported by diamido-donor ligands

Reactions of the lithiated diamido-pyridine or diamido-amine ligands Li(2)N(2)N(py) or Li(2)N(2)N(am) with [W(NAr)Cl(4)(THF)] (Ar = Ph or 2,6-C(6)H(3)Me(2); THF = tetrahydrofuran) afforded the corresponding imido-dichloride complexes [W(NAr)(N(2)N(py))Cl(2)] (R = Ph, 1, or 2,6-C(6)H(3)Me(2), 2) or [W(NAr)(N(2)N(am))Cl(2)] (R = Ph, 3, or 2,6-C(6)H(3)Me(2), 4), respectively, where N(2)N(py) = MeC(2-C(5)H(4)N)(CH(2)NSiMe(3))(2) and N(2)N(am) = Me(3)SiN(CH(2)CH(2)NSiMe(3))(2). Subsequent reactions of 1 with MeMgBr or PhMgCl afforded the dimethyl or diphenyl complexes [W(NPh)(N(2)N(py))R(2)] (R = Me, 5, or Ph, 6), respectively, which have both been characterized by single crystal X-ray diffraction. Reactions of Li(2)N(2)N(py) or Li(2)N(2)N(am) with [Mo(NR)(2)Cl(2)(DME)] (R = (t)Bu or Ph; DME = 1,2-dimethoxyethane) afforded the corresponding bis(imido) complexes [Mo(NR)(2)(N(2)N(py))] (R = (t)Bu, 7, or Ph, 8) and [Mo(N(t)Bu)(2)(N(2)N(am))] (9).     

Synthesis,molecular structure,and C-C coupling reactions of carbeneruthenium(II) complexes with C5H5Ru(=CRR') and C5Me5Ru(=CRR') as molecular units

The ethene derivatives [(eta(5)-C(5)R(5))RuX(C(2)H(4))(PPh(3))] with R=H and Me, which have been prepared from the eta(3)-allylic compounds [(eta(5)-C(5)R(5))Ru(eta(3)-2-MeC(3)H(4))(PPh(3))] (1, 2) and acids HX under an ethene atmosphere, are excellent starting materials for the synthesis of a series of new halfsandwich-type ruthenium(II) complexes. The olefinic ligand is replaced not only by CO and pyridine, but also by internal and terminal alkynes to give (for X=Cl) alkyne, vinylidene, and allene compounds of the general composition [(eta(5)-C(5)R(5))RuCl(L)(PPh(3))] with L=C(2)(CO(2)Me)(2), Me(3)SiC(2)CO(2)Et, C=CHCO(2)R, and C(3)H(4). The allenylidene complex [(eta(5)-C(5)H(5))RuCl(=C=C=CPh(2))(PPh(3))] is directly accessible from 1 (R=H) in two steps with the propargylic alcohol HC triple bond CC(OH)Ph(2) as the precursor. The reactions of the ethene derivatives [(eta(5)-C(5)H(5))RuX(C(2)H(4))(PPh(3))] (X=Cl, CF(3)CO(2)) with diazo compounds RR'CN(2) yield the corresponding carbene complexes [(eta(5)-C(5)R(5))RuX(=CRR')(PPh(3))], while with ethyl diazoacetate (for X=Cl) the diethyl maleate compound [(eta(5)-C(5)H(5))RuCl[eta(2)-Z-C(2)H(2)(CO(2)Et)(2)](PPh(3))] is obtained. Halfsandwich-type ruthenium(II) complexes [(eta(5)-C(5)R(5))RuCl(=CHR')(PPh(3))] with secondary carbenes as ligands, as well as cationic species [(eta(5)-C(5)H(5))Ru(=CPh(2))(L)(PPh(3))]X with L=CO and CNtBu and X=AlCl(4) and PF(6), have also been prepared. The neutral compounds [(eta(5)-C(5)H(5))RuCl(=CRR')(PPh(3))] react with phenyllithium, methyllithium, and the vinyl Grignard reagent CH(2)=CHMgBr by displacement of the chloride and subsequent C-C coupling to generate halfsandwich-type ruthenium(II) complexes with eta(3)-benzyl, eta(3)-allyl, and substituted olefins as ligands. Protolytic cleavage of the metal-allylic bond in [(eta(5)-C(5)H(5))Ru(eta(3)-CH(2)CHCR(2))(PPh(3))] with acetic acid affords the corresponding olefins R(2)C=CHCH(3). The by-product of this process is the acetato derivative [(eta(5)-C(5)H(5))Ru(kappa(2)-O(2)CCH(3))(PPh(3))], which can be reconverted to the carbene complexes [(eta(5)-C(5)H(5))RuCl(=CR(2))(PPh(3))] in a one-pot reaction with R(2)CN(2) and Et(3)NHCl.