Synthesis and characterization of triazenide and triazene complexes of ruthenium and osmium

Triazenide [M(eta2-1,3-ArNNNAr)P4]BPh4 [M = Ru, Os; Ar = Ph, p-tolyl; P = P(OMe)3, P(OEt)3, PPh(OEt)2] complexes were prepared by allowing triflate [M(kappa2-OTf)P4]OTf species to react first with 1,3-ArN=NN(H)Ar triazene and then with an excess of triethylamine. Alternatively, ruthenium triazenide [Ru(eta2-1,3-ArNNNAr)P4]BPh4 derivatives were obtained by reacting hydride [RuH(eta2-H2)P4]+ and RuH(kappa1-OTf)P4 compounds with 1,3-diaryltriazene. The complexes were characterized by spectroscopy and X-ray crystallography of the [Ru(eta2-1,3-PhNNNPh){P(OEt)3}4]BPh4 derivative. Hydride triazene [OsH(eta1-1,3-ArN=NN(H)Ar)P4]BPh4 [P = P(OEt)3, PPh(OEt)2; Ar = Ph, p-tolyl] and [RuH{eta1-1,3-p-tolyl-N=NN(H)-p-tolyl}{PPh(OEt)2}4]BPh4 derivatives were prepared by allowing kappa1-triflate MH(kappa1-OTf)P4 to react with 1,3-diaryltriazene. The [Os(kappa1-OTf){eta1-1,3-PhN=NN(H)Ph}{P(OEt)3}4]BPh4 intermediate was also obtained. Variable-temperature NMR studies were carried out using 15N-labeled triazene complexes prepared from the 1,3-Ph15N=N15N(H)Ph ligand. Osmium dihydrogen [OsH(eta2-H2)P4]BPh4 complexes [P = P(OEt)3, PPh(OEt)2] react with 1,3-ArN=NN(H)Ar triazene to give the hydride-diazene [OsH(ArN=NH)P4]BPh4 derivatives. The X-ray crystal structure determination of the [OsH(PhN=NH){PPh(OEt)2}4]BPh4 complex is reported. A reaction path to explain the formation of the diazene complexes is also reported.     

Polystyrene-supported dicyclohexylphenylphosphine adducts of amine- and phosphite-based palladacycles in the Suzuki coupling of aryl chlorides

The polystyrene-immobilised palladacyclic complexes [Pd(TFA)(kappa2-N,C-C6H4CH2NMe2){P(C6H4-4-PS)Cy2}] and [PdCl(kappa2-P,C-{P(OC6H2-2,4-tBu2)(OC6H3-2,4-tBu2)2}{P(C6H4-4-PS)Cy2}](PS = polystyrene) and the homogeneous analogues [Pd(TFA)(kappa2-N,C-C6H4CH2NMe2)(PPhCy2)] and PdCl(kappa2-P,C-{P(OC6H2-2,4-tBu2)(OC6H3-2,4-tBu2)2}(PPhCy2)] were synthesised and characterised. The X-ray structure of one of the homogeneous analogues, [Pd(TFA)(kappa2-N,C-C6H4CH2NMe2)(PPhCy2)] was determined. All the complexes have been tested and show good activity in the Suzuki coupling of aryl chloride substrates. While the polystyrene-immobilised complexes are not recyclable, they are easily extracted and show low levels of palladium leaching.     

Reactivity of niobium(v) and tantalum(v) halides with carbonyl compounds: synthesis of simple coordination adducts, C-H bond activation, C=O protonation, and halide transfer

The metal halides of Group 5 MX(5) (M = Nb, Ta; X = F, Cl, Br) react with ketones and acetylacetones affording the octahedral complexes [MX(5)(ketone)] () and [TaX(4){kappa(2)(O)-OC(Me)C(R)C(Me)O}] (R = H, Me, ), respectively. The adducts [MX(5)(acetone)] are still reactive towards acetone, acetophenone or benzophenone, giving the aldolate species [MX(4){kappa(2)(O)-OC(Me)CH(2)C(R)(R')O}] (). The syntheses of (M = Ta, X = F, R = R' = Ph) and (M = Ta, X = Cl, R = Me, R' = Ph) take place with concomitant formation of [(Ph(2)CO)(2)-H][TaF(6)], and [(MePhCO)(2)-H][TaCl(6)], respectively. The compounds [acacH(2)][TaF(6)], and [TaF{OC(Me)C(Me)C(Me)O}(3)][TaF(6)], have been isolated as by-products in the reactions of TaF(5) with acacH and 3-methyl-2,4-pentanedione, respectively. The molecular structures of, and have been ascertained by single crystal X-ray diffraction studies.     

Copper(I) complexes of bis(2-(diphenylphosphino)phenyl) ether: synthesis, reactivity, and theoretical calculations

The tricoordinated cationic Cu(I) complex [Cu(kappa2-P,P'-DPEphos)(kappa1-P-DPEphos)][BF4] (1) (DPEphos = bis(2-(diphenylphosphino)phenyl) ether) containing a dangling phosphorus center was synthesized from the reaction of [Cu(CH3CN)4][BF4] with DPEphos in a 1:2 molar ratio in dichloromethane. When complex 1 is treated with MnO2, elemental sulfur, or selenium, the uncoordinated phosphorus atom undergoes oxidation to form a P=E bond resulting in the formation of complexes of the type [Cu(kappa2-P,P'-DPEphos)(kappa2-P,E-DPEphos-E)][BF4] (2, E = O; 3, E = S; 4, E = Se) containing a Cu-E bond. The zigzag polymeric CuI complex [Cu(kappa2-P,P'-DPEphos)(micro-4,4'-bpy)]n[BF4]n (5) was prepared by the reaction of [Cu(CH3CN)4][BF4] with DPEphos and 4,4'-bipyridine in an equimolar ratio. The stereochemical influences of DPEphos on its coordination behavior are examined by density functional theory calculations.     

Syntheses and molecular structures of new cali

An unusual disproportionation reaction of the molybdenum(IV) and tungsten(IV) chlorides [MCl4L2] (M=Mo, L=Et2S, Et2O; M=W; L= Et2S) in the presence of p-tBu-calix[4]arene (Cax(OH)4) and triethylamine leads to d0 complexes [(CaxO4)[CaxO2(OH)2]M] (1) and d3 compounds (HNEt3)2[(CaxO4)2M2] (2). Complexes la (M = Mo), 1b (M = W), and the HCl adduct of 2a (M = Mo) have been structurally characterized. Compound 1a represents one of the few examples of a well-characterized molybdenum(VI) hexa-alkoxide complex of the type [Mo(OR)6]. Isolation and structural characterization of the side product [(CaxO4W)[kappa2(O)-kappa1(O)-CaxO3(OH)](CaxO4WCl)] (3) suggests the intermediacy of chloro-containing calix[4]arene complexes in these reaction mixtures. The reaction of 1a with HCI provides [CaxO4MoCl2] (4a), the first well-defined example of a mixed molybdenum(VI) alkoxide halide compound of the general formula [MoClx(OR)6-x].     

Pincer Ru and Os complexes as efficient catalysts for racemization and deuteration of alcohols

The pincer complexes [MX(CNN)(PP)] (M = Ru, Os; X = Cl, OTf; HCNN = 1-(6-arylpyridin-2-yl)methanamine; PP = diphosphine) have proven to efficiently catalyze both racemization and deuteration of alcohols in the presence of a base. Chiral alcohols have been racemized at 30-50 °C using 1 mol% of Ru or Os pincer complexes and 5 mol% of KOtBu in 2-propanol. Primary and secondary alcohols are efficiently deuterated at the α position, with respect to the OH group, using 2-propanol-d(8) as solvent with Ru or Os pincer complexes and KOtBu at 30-50 °C. For secondary alcohols incorporation of deuterium at the β position has also been observed. In 2-propanol-d(8) the pincer complexes catalyze the simultaneous deuteration and racemization of (S)-1-phenylethanol, the two processes being strictly correlated. For both reactions much the same activity has been observed with the Ru and Os complexes. The pincer complexes display a superior activity with respect to the related compounds [MCl(2)(NN)(PP)] (NN = bidentate amine or pyridine ligand). The synthesis of the new complexes [MCl(CNN)(PP)] (M = Ru, 2, 4 and Os, 6, 7; PP = dppb, dppf) and [Ru(OTf)(CNN)(dppb)] (3) is also reported.     

New cationic and zwitterionic Cp*M(kappa2-P,S) complexes (M = Rh, Ir): divergent reactivity pathways arising from alternative modes of ancillary ligand participation in substrate activation

Treatment of 0.5 equiv of [Cp*IrCl(2)](2) with 1/3-P(i)Pr(2)-2-S(t)Bu-indene afforded Cp*Ir(Cl)(kappa(2)-3-P(i)Pr(2)-2-S-indene) (1) in 95% yield (Cp* = eta(5)-C(5)Me(5)). Addition of AgOTf or LiB(C(6)F(5))(4) x 2.5 OEt(2) to 1 gave [Cp*Ir(kappa(2)-3-P(i)Pr(2)-2-S-indene)](+)X(-) ([2](+)X(-); X = OTf, 78%; X = B(C(6)F(5))(4), 82%), which represent the first examples of isolable coordinatively unsaturated [Cp'Ir(kappa(2)-P,S)](+)X(-) complexes. Exposure of [2](+)OTf(-) to CO afforded [2 x CO](+)OTf(-) in 91% yield, while treatment of [2](+)B(C(6)F(5))(4)(-) with PMe(3) generated [2 x PMe(3)](+)B(C(6)F(5))(4)(-) in 94% yield. Treatment of 1 with K(2)CO(3) in CH(3)CN allowed for the isolation of the unusual adduct 3 x CH(3)CN (41% isolated yield), in which the CH(3)CN bridges the Lewis acidic Cp*Ir and Lewis basic indenide fragments of the targeted coordinatively unsaturated zwitterion Cp*Ir(kappa(2)-3-P(i)Pr(2)-2-S-indenide) (3). In contrast to the formation of [2 x CO](+)OTf(-), exposure of 3 x CH(3)CN to CO did not afford 3 x CO; instead, a clean 1:1 mixture of (kappa(2)-3-P(i)Pr(2)-2-S-indene)Ir(CO)(2) (4) and 1,2,3,4-tetramethylfulvene was generated. Treatment of [2](+)OTf(-) with Ph(2)SiH(2) resulted in the net loss of Ph(2)Si(OTf)H to give Cp*Ir(H)(kappa(2)-3-P(i)Pr(2)-2-S-indene) (5) in 44% yield. In contrast, treatment of [2](+)B(C(6)F(5))(4)(-) with Ph(2)SiH(2) or PhSiH(3) proceeded via H-Si addition across Ir-S to give the corresponding [Cp*Ir(H)(kappa(2)-3-P(i)Pr(2)-2-S(SiHPhX)-indene)](+)B(C(6)F(5))(4)(-) complexes 6a (X = Ph, 68%) or 6b (X = H, 77%), which feature a newly established S-Si linkage. Compound 6a was observed to effect net C-O bond cleavage in diethyl ether with net loss of Ph(2)Si(OEt)H, affording [Cp*Ir(H)(kappa(2)-3-P(i)Pr(2)-2-SEt-indene)](+)B(C(6)F(5))(4)(-) (7) in 77% yield. Furthermore, 6a proved capable of transferring Ph(2)SiH(2) to acetophenone, with concomitant regeneration of [2](+)B(C(6)F(5))(4)(-); however, [2](+)X(-) did not prove to be effective ketone hydrosilylation catalysts. Treatment of 1/3-P(i)Pr(2)-2-S(t)Bu-indene with 0.5 equiv of [Cp*RhCl(2)](2) gave Cp*Rh(Cl)(kappa(2)-3-P(i)Pr(2)-2-S-indene) (8) in 94% yield. Combination of 8 and LiB(C(6)F(5))(4) x 2.5 Et(2)O produced the coordinatively unsaturated cation [Cp*Rh(kappa(2)-3-P(i)Pr(2)-2-S-indene)](+)B(C(6)F(5))(4)(-) ([9](+)B(C(6)F(5))(4)(-)), which was transformed into [Cp*Rh(H)(kappa(2)-3-P(i)Pr(2)-2-S(SiHPh(2))-indene)](+)B(C(6)F(5))(4)(-) (10) via net H-Si addition of Ph(2)SiH(2) to Rh-S. Unlike [2](+)X(-), complex [9](+)B(C(6)F(5))(4)(-) was shown to be an effective catalyst for ketone hydrosilylation. Treatment of 3 x CH(3)CN with Ph(2)SiH(2) resulted in the loss of CH(3)CN, along with the formation of Cp*Ir(H)(kappa(2)-3-P(i)Pr(2)-2-S-(1-diphenylsilylindene)) (11) (64% isolated yield) as a mixture of diastereomers. The formation of 11 corresponds to heterolytic H-Si bond activation, involving net addition of H(-) and Ph(2)HSi(+) fragments to Ir and indenide in the unobserved zwitterion 3. Crystallographic data are provided for 1, [2 x CO](+)OTf(-), 3 x CH(3)CN, 7, and 11. Collectively, these results demonstrate the versatility of donor-functionalized indene ancillary ligands in allowing for the selection of divergent metal-ligand cooperativity pathways (simply by ancillary ligand deprotonation) in the activation of small molecule substrates.     

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.     

Reactivity of niobium and tantalum pentahalides with cyclic ethers and the isolation and characterization of intermediates in the polymerization of tetrahydrofuran

The complexes MX5(THF) (M = Nb, X = Cl, 2a; M = Ta, X = F, 2c, X = Cl, 2d) and [MX4(THF){O(CH2)4O(CH2)3CH2)}][MX6] (M = Nb, X = Cl, 3a; M = Ta, X = Cl, 3d, X = Br, 3e, X = I, 3f) result from reactions of MX5 with 0.5 and 1.5 equiv of THF, respectively. Compounds 3 contain the unprecedented 4-(tetrahydrofuran-1-ium)-butan-1-oxo ligand and are likely to play a role in the course of THF polymerization catalyzed by MX5. The addition of L (L = 2,5-dimethyltetrahydrofuran, tetrahydropyran, 1,4-dioxane) to MX5 results in the formation of the hexacoordinated complexes MX5(L). The molecular structures of 2d, 3d, and NbCl5(dioxane), 6a, have been ascertained by X-ray diffraction studies.     

Five-coordinate Pd(II) orthometallated triarylphosphite complexes

The reaction of the orthopalladated triarylphosphite complexes [{Pd(mu-Cl){kappa(2)-P,C-P(OC(6)H(2)-2,4-R(2))(OC(6)H(3)-2,4-R(2))}(2)] (R = H, (t)Bu) with bis(2-diphenylphosphinoethyl)phenylphosphine leads to a five-coordinate palladium(II) (R = H) and a mixture containing four-and five-coordinate species (R = (t)Bu). The crystal structure of the five-coordinate species [Pd{kappa(2)-P,C-(P(OC(6)H(4))(OC(6)H(5))(2)}{bis(2-diphenylphosphinoethyl)phenylphosphine}][SbF(6)] is presented. This complex reacts with hydrogen peroxide or [AuCl(tht)] to give four-coordinate complexes in which the displaced phosphine residue is either oxidised or coordinated to gold chloride; this demonstrates that the five-coordinate complexes are labile in solution. By contrast, the reactions of the dimeric precursors with 1,1,1-tris(diphenylphosphinomethyl)ethane give four-coordinate complexes in the solid state, although evidence is presented that the smaller phosphite-containing system is five-coordinate at room temperature or higher in solution.     

N-Phosphino-amidines and -guanidines: synthesis, structure and P,N-chelate chemistry

The syntheses of the cyclic N-phosphino-amidines and -guanidines Ph2PN(Pri)C(NPri2)N(Pri) ( 1) and Ph2PN(c-Hex)C(R)N(c-Hex) [R = piperazino ( 2), morpholino ( 3), Me ( 4), and Ph ( 5)] are reported. DFT studies have identified the preferred structures for compounds 1-5 with the E-configuration being the most stable form for the N-phosphino-amidines, while the Z-conformation is preferred for the N-phosphino-guanidines something that highlights the potential of such systems to act as kappa2-P,N-chelates. The differences in donor characteristics of 2-5 have been probed through the study of their corresponding P(V) selenide derivatives ( 6-9) and their complexes with the cis-RhCl(CO) (10-12) and cis-PdCl2 (13-17) fragments. In line with the DFT studies both the amidines and guanidines are found to coordinate as kappa2-P,N-chelates, with the latter being moderately weaker donor ligands. The molecular structures of compounds 3 and 4, together with those of the Rh and Pd complexes 10 and 15, respectively, have been determined in the solid state by X-ray crystallography, the latter confirming bidentate kappa2-P,N-chelation.     

New coordination modes at molybdenum for 2-diphenylphosphinoaniline derived ligands

The complexes [MoCl3(1-N,2-Ph2P-C6H4)2] (1) and {MoCl(Nt-Bu)[1-micro(N),2-(Ph2P)C6H4]}2 (2) have been obtained from the reaction of 2-diphenylphosphinoaniline [1,2(NH2)(Ph2P)C6H4] with either sodium molybdate [Na2MoO4] (in the presence of Et3N and Me3SiCl) or [MoCl2(Nt-Bu)2(DME)]; the crystal structure of 1 reveals a novel MoNC2PN six-membered conjugated ring system derived from a P-N coupling reaction between two ligands, whilst that of 2 reveals bridging imido/terminal phosphine ligation.     

Synthesis of triamidoamine ligands of the type (ArylNHCH(2)CH(2))(3)N and molybdenum and tungsten complexes that contain an [ArylNCH(2)CH(2))(3)N]3- ligand

Aryl bromides react with (H(2)NCH(2)CH(2))(3)N in a reaction catalyzed by Pd(2)(dba)(3) in the presence of BINAP and NaO-t-Bu to give the arylated derivatives (ArylNHCH(2)CH(2))(3)N [Aryl = C(6)H(5) (1a), 4-FC(6)H(4) (1b), 4-t-BuC(6)H(4) (1c), 3,5-Me(2)C(6)H(3) (1d), 3,5-Ph(2)C(6)H(3) (1e), 3,5-(4-t-BuC(6)H(4))(2)C(6)H(3) (1f), 2-MeC(6)H(4) (1g), 2,4,6-Me(3)C(6)H(2) (1h)]. Reactions between (ArNHCH(2)CH(2))(3)N (Ar = C(6)H(5), 4-FC(6)H(4), 3,5-Me(2)C(6)H(3), and 3,5-Ph(2)C(6)H(3)) and Mo(NMe(2))(4) in toluene at 70 degrees C lead to [(ArNHCH(2)CH(2))(3)N]Mo(NMe(2)) complexes in yields ranging from 64 to 96%. Dimethylamido species (Ar = 4-FC(6)H(4), 3,5-Me(2)C(6)H(3)) could be converted into paramagnetic [(ArNHCH(2)CH(2))(3)N]MoCl species by treating them with 2,6-lutidinium chloride in tetrahydrofuran (THF). The "direct reaction" between 1a-f and MoCl(4)(THF)(2) in THF followed by 3 equiv of MeMgCl yielded [(ArNHCH(2)CH(2))(3)N]MoCl species (3a-f) in high yield. If 4 equiv of LiMe instead of MeMgCl are employed in the direct reaction, then [(ArNHCH(2)CH(2))(3)N]MoMe species are formed. Tungsten species, [(ArNHCH(2)CH(2))(3)N]WCl, could be prepared by analogous "direct" methods. Cyclic voltammetric studies reveal that MoCl complexes become more difficult to reduce as the electron donating ability of the [ArylNCH(2)CH(2))(3)N]3- ligand increases, and the reductions become less reversible, consistent with ready loss of chloride from ([(ArNHCH(2)CH(2))(3)N]MoCl)(-). Tungsten complexes are more difficult to reduce, and reductions are irreversible on the CV time scale.     

Imidomolybdenum(IV) porphyrin complexes: synthesis, characterization, and intermetal imido transfer reactivity

The imido(meso-tetra-p-tolylporphyrinato)molybdenum(IV) complexes, (TTP)Mo=NR, where R = C6H5 (1a), p-CH3C6H4 (1b), 2,4,6-(CH3)3C6H2 (1c), and 2,6-(i-Pr)2C6H4 (1d), can be prepared by the reaction of (TTP)MoCl2 with 2 equiv of LiNHR in toluene. Upon treatment of the imido complexes with pyridine derivatives, NC5H4-p-X (X = CH3, CH(CH3)2, C[triple bond]N), new six-coordinate complexes, (TTP)Mo=NR.NC5H4-p-X, were observed. The reaction between the molybdenum imido complexes, (TTP)Mo=NC6H5 or (TTP)Mo=NC6H4CH3, and (TTP)Ti(eta2-PhC[triple bond]CPh) resulted in complete imido group transfer and two-electron redox of the metal centers to give (TTP)Mo(eta2-PhC[triple bond]CPh) and (TTP)Ti=NC6H5 or (TTP)Ti=NC6H4CH3.     

Ruthenium(II) complexes containing bis(2-(diphenylphosphino)phenyl) ether and their catalytic activity in hydrogenation reactions

The half-sandwich complexes [(eta5-C5H5)RuCl(DPEphos)] (1) and [{(eta6-p-cymene)RuCl2}2(mu-DPEphos)] (2) were synthesized by the reaction of bis(2-(diphenylphosphino)phenyl) ether (DPEphos) with a mixture of ruthenium trichloride trihydrate and cyclopentadiene and with [(eta6-p-cymene)RuCl2]2, respectively. Treatment of DPEphos with cis-[RuCl2(dmso)4] afforded fac-[RuCl2(kappa3-P,O,P-DPEphos)(dmso)] (3). The dmso ligand in 3 can be substituted by pyridine, 2,2'-bipyridine, 4,4'-bipyridine, and PPh3 to yield trans,cis-[RuCl2(DPEphos)(C5H5N)2] (4), cis,cis-[RuCl2(DPEphos)(2,2'-bipyridine)] (5), trans,cis-[RuCl2(DPEphos)(mu-4,4'-bipyridine)]n (6), and mer,trans-[RuCl2(kappa3-P,P,O-DPEphos)(PPh3)] (7), respectively. Refluxing [(eta6-p-cymene)RuCl2]2 with DPEphos in moist acetonitrile leads to the elimination of the p-cymene group and the formation of the octahedral complex cis,cis-[RuCl2(DPEphos)(H2O)(CH3CN)] (8). The structures of the complexes 1-5, 7, and 8 are confirmed by X-ray crystallography. The catalytic activity of these complexes for the hydrogenation of styrene is studied.     

Synthesis, properties and structures of eight-coordinate zirconium(IV) and hafnium(IV) halide complexes with phosphorus and arsenic ligands

Eight-coordinate [MX(4)(L-L)(2)] (M = Zr or Hf; X = Cl or Br; L-L = o-C(6)H(4)(PMe(2))(2) or o-C(6)H(4)(AsMe(2))(2)) were made by displacement of Me(2)S from [MX(4)(Me(2)S)(2)] by three equivalents of L-L in CH(2)Cl(2) solution, or from MX(4) and L-L in anhydrous thf solution. The [MI(4)(L-L)(2)] were made directly from reaction of MI(4) with the ligand in CH(2)Cl(2) solution. The very moisture-sensitive complexes were characterised by IR, UV/Vis, and (1)H and (31)P NMR spectroscopy and microanalysis. Crystal structures of [ZrCl(4)[o-C(6)H(4)(AsMe(2))(2)](2)], [ZrBr(4)[-C(6)H(4)(PMe(2))(2)](2)], [ZrI(4)[o-C(6)H(4)(AsMe(2))(2)](2)] and [HfI(4)[o-C(6)H(4)(AsMe(2))(2)](2)] all show distorted dodecahedral structures. Surprisingly, unlike the corresponding Ti(iv) systems, only the eight-coordinate complex was found in each system. In contrast, the ligand o-C(6)H(4)(PPh(2))(2) forms only six-coordinate complexes [MX(4)[-C(6)H(4)(PPh(2))(2)]] which were fully characterised spectroscopically and analytically. Surprisingly the tripodal triarsine, MeC(CH(2)AsMe(2))(3), also produces eight-coordinate [MX(4)[MeC(CH(2)AsMe(2))(3)](2)] in which the triarsines bind as bidentates in a distorted dodecahedral structure. There is no evidence for seven-coordination as found in some thioether systems.     

Synthesis and structures of crystalline Li, Al and Sn(II) 1-azaallyls and beta-diketiminates derived from [Li{mu,eta3-N(SiMe3)C(Ad)C(H)SiMe3}]2 (Ad = 1-adamantyl)

The crystalline dimeric 1-azaallyllithium complex [Li{mu,eta(3-N(SiMe3)C(Ad)C(H)SiMe3}]2 (1) was prepared from equivalent portions of Li[CH(SiMe3)2] and 1-cyanoadamantane (AdCN). Complex was used as precursor to each of the crystalline complexes 2-8 which were obtained in good yield. By 1-azaallyl ligand transfer, 1 afforded (i) [Al{eta3-N(SiMe3)C(Ad)C(H)SiMe3}{kappa1-N(SiMe3)C(Ad)=C(H)SiMe3-E}Me] (5) with [AlCl2Me](2), (ii) [Sn{eta3-N(SiMe3)C(Ad)C(H)SiMe3}2] (7) with Sn[N(SiMe3)2]2, and (iii) [Li(N{C(Ad)=C(H)SiMe3-E}{Si(NN)SiMe3})(thf)2] (8) with the silylene Si[(NCH(2)Bu(t))2C6H(4)-1,2] [= Si(NN)]. By insertion into the C[triple bond, length as m-dash]N bond of the appropriate cyanoarene RCN, gave the beta-diketiminate [Li{mu-N(SiMe3)C(Ad)C(H)C(R)NSiMe3}]2 [R = Ph (2), C(6)H(4)Me-4 (3)], and yielded [Al{kappa2-N(SiMe3)C(Ad)C(H)C(Ph)NSiMe3}{kappa1-N(SiMe3)C(Ad)=C(H)SiMe3-E}Me] (6). The beta-diketiminate [Al{kappa2-N(SiMe3)C(Ad)C(H)C(Ph)NSiMe3}Me2] (4) was prepared from 2 and [AlClMe2]2. The X-ray structures of 1 and 3-8 are presented. Multinuclear NMR spectra in C6D6 or C6D5CD3 have been recorded for each of 1-8; such data on 8 revealed that in solution two minor isomers were also present.     

Synthesis and reactions of molybdenum triamidoamine complexes containing hexaisopropylterphenyl substituents

We have synthesized a triamidoamine ligand ([(RNCH(2)CH(2))(3)N](3)(-)) in which R is 3,5-(2,4,6-i-Pr(3)C(6)H(2))(2)C(6)H(3) (hexaisopropylterphenyl or HIPT). The reaction between MoCl(4)(THF)(2) and H(3)[HIPTN(3)N] in THF followed by 3.1 equiv of LiN(SiMe(3))(2) led to formation of orange [HIPTN(3)N]MoCl. Reduction of MoCl (Mo = [HIPTN(3)N]Mo) with magnesium in THF under dinitrogen led to formation of salts that contain the ((Mo(N(2)))(-) ion. The (Mo(N(2)))(-) ion can be oxidized by zinc chloride to give Mo(N(2)) or protonated to give MoN=NH. The latter was found to decompose to yield MoH. Other relevant compounds that have been prepared include (Mo=N-NH(2))(+) (by protonation of MoN=NH), M=1;N, (Mo=NH)(+) (by protonation of M=N), and (Mo(NH(3)))(+) (by treating MoCl with ammonia). (The anion is usually (B(3,5-(CF(3))(2)C(6)H(3))(4))(-) = (BAr'(4))(-).) X-ray studies were carried out on (Mg(DME)(3))(0.5)[Mo(N(2))], MoN=NMgBr(THF)(3), Mo(N(2)), M=N, and (Mo(NH(3)))(BAr'(4)). These studies suggest that the HIPT substituent on the triamidoamine ligand creates a cavity that stabilizes a variety of complexes that might be encountered in a hypothetical Chatt-like dinitrogen reduction scheme, perhaps largely by protecting against bimolecular decomposition reactions.     

Ruthenium(II) polypyridyl complexes: potential precursors, metalloligands, and topo II inhibitors

Neutral and cationic mononuclear complexes containing both group 15 and polypyridyl ligands [Ru(kappa3-tptz)(PPh3)Cl2] [1; tptz=2,4,6-tris(2-pyridyl)-1,3,5-triazine], [Ru(kappa3-tptz)(kappa2-dppm)Cl]BF4 [2; dppm=bis(diphenylphosphino)methane], [Ru(kappa3-tptz)(PPh3)(pa)]Cl (3; pa=phenylalanine), [Ru(kappa3-tptz)(PPh3)(dtc)]Cl (4; dtc=diethyldithiocarbamate), [Ru(kappa3-tptz)(PPh3)(SCN)2] (5) and [Ru(kappa3-tptz)(PPh3)(N3)2] (6) have been synthesized. Complex 1 has been used as a metalloligand in the synthesis of homo- and heterodinuclear complexes [Cl2(PPh3)Ru(micro-tptz)Ru(eta6-C6H6)Cl]BF4 (7), [Cl2(PPh3)Ru(mu-tptz)Ru(eta6-C10H14)Cl]PF6 (8), and [Cl2(PPh3)Ru(micro-tptz)Rh(eta5-C5Me5)Cl]BF4 (9). Complexes 7-9 present examples of homo- and heterodinuclear complexes in which a typical organometallic moiety [(eta6-C6H6)RuCl]+, [(eta6-C10H14)RuCl]+, or [(eta5-C5Me5)RhCl]+ is bonded to a ruthenium(II) polypyridine moiety. The complexes have been fully characterized by elemental analyses, fast-atom-bombardment mass spectroscopy, NMR (1H and 31P), and electronic spectral studies. Molecular structures of 1-3, 8, and 9 have been determined by single-crystal X-ray diffraction analyses. Complex 1 functions as a good precursor in the synthesis of other ruthenium(II) complexes and as a metalloligand. All of the complexes under study exhibit inhibitory effects on the Topoisomerase II-DNA activity of filarial parasite Setaria cervi and beta-hematin/hemozoin formation in the presence of Plasmodium yoelii lysate.     

Synthesis, spectroscopy and electronic structure of the vinylidene and alkynyl complexes [W(C=CHR)(dppe)(η-C₇H₇)](+) and [W(C≡CR)(dppe)(η-C₇H₇](n+) (n = 0 or 1)

The first examples of vinylidene complexes of the cycloheptatrienyl tungsten system [W(C=CHR)(dppe)(η-C?H?)](+) (dppe = Ph?PCH?CH?PPh?; R = H, 3; Ph, 4; C?H?-4-Me, 5) have been synthesised by reaction of [WBr(dppe)(η-C?H?)], 1, with terminal alkynes HC≡CR; a one-pot synthesis of 1 from [WBr(CO)?(η-C?H?)] facilitates its use as a precursor. The X-ray structure of 4[PF?] reveals that the vinylidene ligand substituents lie in the pseudo mirror plane of the W(dppe)(η-C?H?) auxiliary (vertical orientation) with the phenyl group located syn to the cycloheptatrienyl ring. Variable temperature 1H NMR investigations on [W(C=CH?)(dppe)(η-C?H?)][PF?], 3, estimate the energy barrier to rotation about the W=C(α) bond as 62.5 ± 2 kJ mol?1; approximately 10 kJ mol?1 greater than for the molybdenum analogue. Deprotonation of 4 and 5 with KOBu(t) yields the alkynyls [W(C≡CR)(dppe)(η-C?H?)] (R = Ph, 6; C?H?-4-Me, 7) which undergo a reversible one-electron oxidation at a glassy carbon electrode in CH?Cl? with E(?) values approximately 0.12 V negative of Mo analogues. The 17-electron radicals [6](+) and [7](+) have been investigated by spectroelectrochemical IR, UV-visible and EPR methods. The electronic structures of representative vinylidene (3) and alkynyl (6) complexes have been investigated at the B3LYP/Def2-SVP level. In both cases, electronic structure is characterised by a frontier orbital with significant metal d(z2)character and this dominates the structural and spectroscopic properties of the system.