Highly air-stable anionic mononuclear and neutral binuclear palladium(II) complexes for C-C and C-N bond-forming reactions

The short-bite aminobis(phosphonite), PhN{P(-OC10H6(mu-S)C10H6O-)}2 (2), containing a mesocyclic thioether backbone is synthesized by either treating PhN(PCl2)2 with 2 equiv of thiobis(2,2'-naphthol) or reacting chlorophosphite (-OC10H6(mu-S)C10H6O-)PCl (1) with aniline in the presence of a base. Treatment of 2 with an equimolar amount of Pd(COD)Cl2 in the presence of H2O affords a P-N-P-bridged and P,S-metalated binuclear complex, [PhN(P(-OC10H6(mu-S)C10H6O-)-kappaP)2Pd2Cl2{P(-OC10H6(mu-S)C10H6O-)(O)-kappaP,kappaS}2] (3), whereas the same reaction with 2 equiv of Pd(COD)Cl2 in the presence of H2O and Et3N produces the mononuclear anionic complex [{(-OC10H6(mu-S)C10H6O-)P(O)-kappaP,kappaS}PdCl2](Et3NH) (5). By contrast, reaction of 2 with 2 equiv of Pd(COD)Cl2 and H2O in the absence of Et3N gives the hydrogen phosphonate coordinated complex [{(-OC10H6(mu-S)C10H6O-)P(OH)}PdCl2] (4) which converts to the anionic complex in solution or in the presence of a base. Compound 2 on treatment with Pt(COD)X2 (X = Cl or I) afforded P-coordinated four-membered chelate complexes [PhN(P(-OC10H6(mu-S)C10H6O-)-kappaP)2PtX2] (6 X = Cl, 7 X = I). The crystal structures of compounds 2, 3, 5, and 7 are reported. Compound 3 is the first example of a crystallographically characterized binuclear palladium complex containing a bidentate bridging ligand and its hydrolyzed fragments forming metallacycles containing a palladium-phosphorus sigma bond. All palladium complexes proved to be very good catalysts for the Suzuki-Miyaura and Mizoroki-Heck cross-coupling and amination reactions with excellent turnover numbers (TON up to 1.46 x 105 in the case of the Suzuki-Miyaura reaction).     

Cyclodiphosphazanes with hemilabile ponytails: synthesis, transition metal chemistry (Ru(II), Rh(I), Pd(II), Pt(II)), and crystal and molecular structures of mononuclear (Pd(II), Rh(I)) and bi- and tetranuclear rhodium(I) complexes

Cyclodiphosphazanes having hemilabile ponytails such as cis-[(t)()BuNP(OC(6)H(4)OMe-o)](2) (2), cis-[(t)()BuNP(OCH(2)CH(2)OMe)](2) (3), cis-[(t)BuNP(OCH(2)CH(2)SMe)](2) (4), and cis-[(t)BuNP(OCH(2)CH(2)NMe(2))](2) (5) were synthesized by reacting cis-[(t)()BuNPCl](2) (1) with corresponding nucleophiles. The reaction of 2 with [M(COD)Cl(2)] afforded cis-[MCl(2)(2)(2)] derivatives (M = Pd (6), Pt (7)), whereas, with [Pd(NCPh)(2)Cl(2)], trans-[MCl(2)(2)(2)] (8) was obtained. The reaction of 2 with [Pd(PEt(3))Cl(2)](2), [{Ru(eta(6)-p-cymene)Cl(2)](2), and [M(COD)Cl](2) (M = Rh, Ir) afforded mononuclear complexes of Pd(II) (9), Ru(II) (11), Rh(I) (12), and Ir(I) (13) irrespective of the stoichiometry of the reactants and the reaction condition. In the above complexes the cyclodiphosphazane acts as a monodentate ligand. The reaction of 2 with [PdCl(eta(3)-C(3)H(5))](2) afforded binuclear complex [(PdCl(eta(3)-C(3)H(5)))(2){((t)BuNP(OC(6)H(4)OMe-o))(2)-kappaP}] (10). The reaction of ligand 3 with [Rh(CO)(2)Cl](2) in 1:1 ratio in CH(3)CN under reflux condition afforded tetranuclear rhodium(I) metallamacrocycle (14), whereas the ligands 4 and 5 afforded bischelated binuclear complexes 15 and 16, respectively. The crystal structures of 8, 9, 12, 14, and 16 are reported.     

Large-bite bis(phosphite) ligand containing mesocyclic thioether moieties: synthesis, reactivity, group 11 (Cu(I), Au(I)) metal complexes and anticancer activity studies on a human cervical cancer (HeLa) cell line

The large-bite bis(phosphite) ligand [{(-OC(10)H(6)(mu-S)C(10)H(6)O-)P{mu-(-OC(10)H(6)(mu-S)C(10)H(6)O-)}P(-OC(10)H(6)(mu-S)C(10)H(6)O-)}] (Pinsertion markP) () was obtained by the reaction of PCl(3) and thiobis(2,2'-naphthol) (). The stoichiometric reactions of with elemental sulfur and selenium afforded the corresponding chalcogenide derivatives [(E)Pinsertion markP(E)] (, E = S; , E = Se) in good yield. Treatment of two equivalents of [ClAu(SMe(2))] with afforded a dinuclear complex [ClAu(Pinsertion markP)AuCl] (), whereas the 1 : 1 reaction with CuI yielded the [(Pinsertion markP)CuI] () complex. The copper(i) complex on treatment with various pyridyl derivatives, produced mixed-ligand complexes [(Pinsertion markP)CuI(NC(5)H(5))] (), [(Pinsertion markP)Cu(2,2'-bpy)]I (), [(Pinsertion markP)Cu(1,10-phen)]I () and {[(Pinsertion markP)Cu(4,4'-bpy)]I}(infinity) (). The compounds were tested for their cytotoxic activity on the human cervical cancer (HeLa) cell line. Compounds and were found to inhibit proliferation of HeLa cells significantly. These agents also induced apoptotic cell death in cancer cells. Evidence presented in this study indicated that the compounds and activate the tumor suppressor protein p53 in the colon adenocarcinoma (HCT-116) cell line.     

Synthesis and characterization of novel Pd(II) complexes with chelating and non-chelating heterocyclic iminocarbene ligands

The imidazolium salts [3-R1-1-{2-Ar-imino)-2-R2-ethyl}imidazolium] chloride (C-N; Ar = 2,6-iPr2C6H3; R1/R2 = Me/Me (a), Me/Ph (b), Ph/Me (c), 2,4,6-Me3C6H2 (d), 2,6-iPr2C6H3 (e)) react with Ag(2)O to give Ag(I) iminocarbene complexes (C-N)AgCl (4a-e) in which the iminocarbene ligand is bonded to Ag via the imidazoline-2-ylidene carbon atom. The solid-state structures of 4b and 4d were determined by X-ray crystallography and revealed the presence of monomeric (carbene)AgCl units with Z and E configurations at the imine C=N bonds, respectively. Carbene transfer to Pd occurs when compounds 4b-e are treated with (COD)PdCl2 to yield bis(carbene) complexes (C-N)2PdCl2 (6b-e) containing two kappa1-C bonded iminocarbene moieties. NMR spectroscopic data indicated a trans coordination geometry at Pd. This conclusion was supported by an X-ray structure determination of 6b which clearly demonstrated the non-chelating nature of the iminocarbene ligand system. EXSY 1H NMR spectroscopy suggests that the non-chelating structures undergo E/Z isomerization at the imine C[double bond, length as m-dash]N double bonds in solution. The preparative results contrast our earlier report that the reaction between 4a and (COD)PdCl2 results in a chelating kappa2-C,N bonded iminocarbene complex (C-N)PdCl2. The coordination mode and dynamic behavior of the iminocarbene ligand systems have been found to be dramatically affected by changes in the substitution pattern of the ligand system. Sterically unencumbered systems (a) favor the formation of kappa2-C,N chelate structures containing one iminocarbene moiety per metal upon coordination at Pd(II); these complexes were demonstrated to engage in reversible, solvent-mediated chelate ring-opening reactions. Sterically encumbered systems (b-e) form non-chelating kappa1-C iminocarbene Pd(II) complexes containing two iminocarbene ligands per metal. Transannular repulsions across the chelate ring are believed to be the origin of these structural differences.     

Chelating or bridging Pd(II) and Pt(II) metalloligands from the functional phosphine ligand N-(diphenylphosphino)-1,3,4-thiadiazol-2-amine. New heterometallic Pd(II)/Pt(II) and Pt(II)/Au(I) complexes

The reaction of two equivalents of the functional phosphine ligand N-(diphenylphosphino)-1,3,4-thiadiazol-2-amine Ph2PNHC=NNCHS (2) with [PdCl2(NCPh)2] in the presence of NEt3 gives the neutral, P,N-chelated complex cis-[Pd(Ph2PN=CNN=CHS)2] ([Pd(2-H)2], 3b), which is analogous to the Pt(II) analogue cis-[Pt (Ph2PN=CNN=CHS)2] ([Pt(2-H)2], 3a) reported previously. These complexes function as chelating metalloligands when further coordinated to a metal through each of the CH-N atoms. In the resulting complexes, each endo-cyclic N donor of the thiadiazole rings is bonded to a different metal centre. Thus, the heterodinuclear palladium/platinum complexes cis-[Pt(Ph2PN=CNN=CHS)2PdCl2]([Pt(2-H)2·PdCl2], 4a) and cis-[Pd(Ph2PN=CNN=CHS)2PtCl2]([Pd(2-H)2·PtCl2], 4b) were obtained by reaction with [PdCl2(NCPh)2] and [PtCl2(NCPh)2], respectively. In contrast, reaction of 3a with [AuCl(tht)] occurred instead at the P-bound N atom, and afforded the platinum/digold complex cis-[Pt{Ph2PN(AuCl)=CNN=CHS}2] ([Pt(2-H)2(AuCl)2], 5). For comparison, reaction of 4a with HBF4 yielded cis-[Pt(Ph2PNH=CNN=CHS)2PdCl2](BF4)2([H24a](BF4)2, 6), in which the chelated PdCl2 moiety is retained. Complexes 3b, 4a·CH2Cl2, 4b·0.5C7H8, 5·4CHCl3 and 6 have been structurally characterized by X-ray diffraction.     

Influence of the terminal ligands on the redox properties of the {Pt2(mu-S)2} core in [Pt2(Ph2X(CH2)2XPh2)2(mu-S)2] (X = P or As) complexes and on their reactivity towards metal centres, protic acids and organic electrophiles

In order to explore possible ways for modulating the unusually rich chemistry shown by complexes of formula [L2Pt(mu-S)2PtL2] we have studied the influence of the nature of the terminal ligand L on the chemical properties of the {Pt2(mu-S)2} core. The systematic study we now report allows comparison of the behaviour of [Pt2(dpae)2(mu-S)2](dpae = Ph2As(CH2)2AsPh2) (1) with the already reported analogue [Pt2(dppe)2(mu-S)2](dppe = Ph2P(CH2)2PPh2). Complex 1 as well as the corresponding multimetallic derivatives [Pt(dpae){Pt2(dpae)2(mu-S)2}](BPh4)2 2, [M{Pt2(dpae)2(mu-S)2}2]X2 (M = Cu(II), X = BF4 3; M = Zn(II), X = BPh4 4; M = Cd(II), X = ClO4 5; M = Hg(II), X = Cl 6 or X2 = Cl(1.5)[HCl2](0.5) 6') have been characterized in the solid phase and in solution. Comparison of structural parameters of 1 and 3-6' with those of the corresponding phosphine analogues, together with the results of the electrochemical study for 1, allow us to conclude that replacement of dppe by dpae causes a decrease in basicity of the {Pt2(mu-S)2} core. The study of the reactivity of 1 towards CH2Cl2 and protic acids has led to the structural characterization of [Pt(dpae)(S2CH2)] 9 and [PtCl2(dpae)] 10. Moreover, comparison with the reactivity of [Pt2(dppe)2(mu-S)2] indicates that the stability of the intermediate species as well as the nature of the final products in both multistep reactions are sensitive to the nature of the terminal ligand.     

Triazenide-bridged rhodium-palladium complexes: [I2Rh(mu-p-MeC6H4NNNC6H4Me-p)2Pd(eta(3)-C3H5)]-, a stable paramagnetic [RhPd]4+ species with a localised Rh(II) centre

Deprotonation of mixtures of the triazene complexes [RhCl(CO)2(p-MeC6H4NNNHC6H4Me-p)] and [PdCl(eta(3)-C3H5)(p-MeC6H4NNNHC6H4Me-p)] or [PdCl2(PPh3)(p-MeC6H4NNNHC6H4Me-p)] with NEt3 gives the structurally characterised heterobinuclear triazenide-bridged species [(OC)2Rh(mu-p-MeC6H4NNNC6H4Me-p)2PdLL'] {LL' = eta(3)-C3H5 1 or Cl(PPh3) 2} which, in the presence of Me3NO, react with [NBu(n)4]I, [NBu(n)4]Br, [PPN]Cl or [NBu(n)4]NCS to give [(OC)XRh(mu-p-MeC6H4NNNC6H4Me-p)2PdCl(PPh3)]- (X = I 3-, Br 4-, Cl 5- or NCS 6-) and [NBu(n)4][(OC)XRh(mu-p-MeC6H4NNNC6H4Me-p)2Pd(eta(3)-C3H5)], (X = I 7- or Br 8-). The allyl complexes 7- and 8- undergo one-electron oxidation to the corresponding unstable neutral complexes 7 and 8 but, in the presence of the appropriate halide, oxidative substitution results in the stable paramagnetic complexes [NBu(n)4][X2Rh(mu-p-MeC6H4NNNC6H4Me-p)2Pd(eta(3)-C3H5)], (X = I 9- or Br 10-). X-Ray structural (9-), DFT and EPR spectroscopic studies are consistent with the unpaired electron of 9- and 10- localised primarily on the Rh(II) centre of the [RhPd]4+ core, which is susceptible to oxygen coordination at low temperature to give Rh(III)-bound superoxide.     

PalladiumII and platinumII complexes with heteroditopic 10-(aryl)phenoxarsine (aryl = 2-C6H4OR, R = H, Me, Pr(i)) ligands: solvent-oriented crystallization of cis isomers

The synthesis and characterization of 10-(o-alkoxyphenyl)phenoxarsines 2-ROC6H4As(C6H4)2O (R = H, Me, and Pri, As(C6H4)2O = phenoxarsine) and their platinum(II) and palladium(II) complexes cis-[PtCl2{2-PriOC6H4As(C6H4)2O-kappaAs}2] (1), trans-[PdCl2{2-PriOC6H4As(C6H4)2O-kappaAs}2] (2), cis-[PtCl2{2-HOC6H4As(C6H4)2O-kappaAs}2] (3), cis-[PdCl2{2-HOC6H4As(C6H4)2O-kappaAs}2] (4), cis-[PtI2{2-MeOC6H4As(C6H4)2O-kappaAs}2] (5), and trans-[PdCl2{2-MeOC6H4As(C6H4)2O-kappaAs}2] (6) are reported. The chelate complex cis-[Pt{2-OC6H4As(C6H4)2O-kappaAs,O}2] (7) is also described. The molecular structures of 1-4 and 7 were determined. The short As...O intramolecular interaction found in complexes 1-4 in the solid state was also verified by calculations at the B3LYP/LANL2DZ level for complex 2 and for 10-(o-isopropoxyphenyl)phenoxarsine in the gas phase, and this suggests that the interaction is a characteristic of the ligand rather than a packing effect. Calculations at the B3LYP/LANL2DZ and Oniom(B3LYP/LANL2DZ:uff) levels for complexes 1-4 showed that the solvent plays a crucial role in the crystallization (through geometry constraints) of the kinetically stable cis isomers.     

Palladium complexes of a phosphorus ylide with two stabilizing groups: synthesis, structure, and DFT study of the bonding modes

The phosphorus ylide ligand [Ph3P=C(CO2Me)C(=NPh)CO2Me] (L1) has been prepared and fully characterized by spectroscopic, crystallographic, and density functional theory (DFT) methods (B3LYP level). The reactivity of L1 toward several cationic Pd(II) and Pt(II) precursors, with two vacant coordination sites, has been studied. The reaction of [M(C/\X)(THF)2]ClO4 with L1 (1:1 molar ratio) gives [M(C/\X)(L1)]ClO4 [M = Pd, C/\X = C6H4CH2NMe2 (1), S-C6H4C(H)MeNMe2 (2), CH2-8-C9H6N (3), C6H4-2-NC5H4 (4), o-CH2C6H4P(o-tol)2 (6), eta3-C3H5 (7); M = Pt, C/\X = o-CH2C6H4P(o-tol)2 (5); M(C/\X) = Pd(C6F5)(SC4H8) (8), PdCl2 (9)]. In complexes 1-9, the ligand L1 bonds systematically to the metal center through the iminic N and the carbonyl O of the stabilizing CO2Me group, as is evident from the NMR data and from the X-ray structure of 3. Ligand L1 can also be orthopalladated by reaction with Pd(OAc)2 and LiCl, giving the dinuclear derivative [Pd(mu-Cl)(C6H4-2-PPh2=C(CO2Me)C(CO2Me)=NPh)]2 (10). The X-ray crystal structure of 10 is also reported. In none of the prepared complexes 1-10 was the C(alpha) atom found to be bonded to the metal center. DFT calculations and Bader analysis were performed on ylide L1 and complex 9 and its congeners in order to assess the preference of the six-membered N,O metallacycle over the four-membered C,N and five-membered C,O rings. The presence of two stabilizing groups at the ylidic C causes a reduction of its bonding capabilities. The increasing strength of the Pd-C, Pd-O, and Pd-N bonds along with other subtle effects are responsible for the relative stabilities of the different bonding modes.     

Reaction of a heterotopic P,SAs ligand with group 10 metal(II) complexes: As-S bond cleavage and the formation of two unusual trinuclear structural isomers for Pd and Pt

The synthesis of the heterotopic P,SAs ligand, 1-Ph(2)AsSC(6)H(4)-2-PPh(2) (1) and its reaction with [PdCl(2)(cod)], [PtI(2)(cod)] (cod = 1,5-cyclooctadiene) and NiCl(2)·6H(2)O is reported. Cleavage of the As-S bond of 1 and coordination of the resulting phosphanylthiolato ligand (SC(6)H(4)-2-PPh(2))(-) (SC(6)H(4)-2-PPh(2) = P,S) was observed with formation of [M(P,S)(2)] (M = Ni, Pd, Pt). In the case of Pd and Pt, not only the mononuclear complexes [M(P,S)(2)] formed, but also the trimers of [MX(P,S)] ([MX{(μ-S-SC(6)H(4)-2-PPh(2))-κ(2)S,P}](3) [M = Pd, X = Cl (2) and M = Pt, X = I (4)]). Formation of 2 and 4 was preceded by the trinuclear isomeric intermediates [(cis-M{(μ-S-SC(6)H(4)-2-PPh(2))-κ(2)S,P}(2))-MX(2)-MX{(μ-S-SC(6)H(4)-2-PPh(2))-κ(2)S,P}] [M = Pd, X = Cl (3) and M = Pt, X = I (5)]. The crystal structures of 1-5 and a possible reaction mechanism that leads to 2 and 4 are presented.     

Bis(2-diphenylphosphinoxynaphthalen-1-yl)methane: transition metal chemistry, Suzuki cross-coupling reactions and homogeneous hydrogenation of olefins

Transition metal complexes of bis(2-diphenylphosphinoxynaphthalen-1-yl)methane (1) are described. Bis(phosphinite) 1 reacts with Group 6 metal carbonyls, [Rh(CO)2Cl]2, anhydrous NiCl2, [Pd(C3H5)Cl]2/AgBF4 and Pt(COD)I2 to give the corresponding 10-membered chelate complexes 2, 3 and 5-8. Reaction of 1 with [Rh(COD)Cl]2 in the presence of AgBF4 affords a cationic complex, [Rh(COD){Ph2P(-OC10H6)(mu-CH2)(C10H6O-)PPh2-kappaP,kappaP}]BF4 (4). Treatment of 1 with AuCl(SMe2) gives mononuclear chelate complex, [(AuCl){Ph2P(-OC10H6)(mu-CH2)(C10H6O-)PPh2-kappaP,kappaP}] (9) as well as a binuclear complex, [Au(Cl){mu-Ph2P(-OC10H6)(mu-CH2)(C10H6O-)PPh2-kappaP,kappaP}AuCl] (10) with ligand 1 exhibiting both chelating and bridged bidentate modes of coordination respectively. The molecular structures of 2, 6, 7, 9 and 10 are determined by X-ray studies. The mixture of Pd(OAc)2 and effectively catalyzes Suzuki cross-coupling reactions of a range of aryl halides with aryl boronic acid in MeOH at room temperature or at 60 degrees C, giving generally high yields even under low catalytic loads. The cationic rhodium(I) complex, [Rh(COD){Ph2P(-OC10H6)(mu-CH2)(C10H6O-)PPh2-kappaP,kappaP}]BF4 (4) catalyzes the hydrogenation of styrenes to afford the corresponding alkyl benzenes in THF at room temperature or at 70 degrees C with excellent turnover frequencies.     

Concise syntheses of tridentate PNE ligands and their coordination chemistry with palladium(II) : a solution- and solid-state study

A straightforward methodology for the high-yielding synthesis of the di-functionalised phosphines {Ph2P(CH2)2NC4H8E, E = NMe (1), O (2), S (3)}via base-catalysed Michael addition is described. Reaction of the functionalised tertiary phosphines 1-3 with PdCl2(MeCN)2 affords complexes in which the ligands are bound in a tridentate fashion, namely [PdCl(kappa3-PNE)]Cl (6a, 8) as the predominant products. A kappa2-PN coordination mode was also identified crystallographically for ligand following its reaction with PdCl2(MeCN)2, which afforded [PdCl2(-kappa2-PN)] (6b) in ca. 5% yield. Conductivity studies of solutions of 6a are consistent with an ionic formulation, however the poor solubility of and precluded their study in a similar fashion. Analysis of bulk samples of [PdCl2(1)] (6) and [PdCl2(3)] (8) by 15N and 31P NMR spectroscopy in the solid state as consistent with exclusive tridentate binding of the PNE ligands. An X-ray crystallographic study has probed the coordination of in the unusual salt [PdCl(-kappa3-PNN)]2[Mg(SO4)2(OH2)4] (10) prepared by treating a methanolic solution of with excess MgSO4. No data could be obtained to support the transformation of 6a into 6b on addition of excess chloride. In contrast, 6a reacts regioselectively with the water-soluble phosphine Cy2PCH2CH2NMe3Cl to afford the cis-diphosphine complex cis-[PdCl(Cy2PCH2CH2NMe3Cl)(1-kappa2-PN)]Cl2 (9). Reaction of 1 with PdCl(Me)(COD) results in the formation of the kappa2-PN dichloride complex [PdCl(Me)(1-kappa(2)-PN)] (11). Attempts to prepare [Pd(Me)(MeCN)(-kappa2-PN)][PF6] (12) through reaction of 11 with NaPF6 in MeCN led to decomposition. Treatment of PdMe2(TMEDA) with 1 at low temperature initially affords [PdMe2(1-kappa2-NN)], which isomerises to afford [PdMe(2)(1-kappa(2)-PN)] (13); at temperatures greater than 10 degrees C complex 13 decomposes rapidly.     

Mononuclear (Pd, Pt), heterodinuclear (PdAg, PtAg), and tetranuclear (Pd2Ag2, Pt2Ag2) 1,1-ethylenedithiolato complexes

lp;&-5q;1 The reactions of [Tl2[S2C=C[C(O)Me]2]]n with [MCl2L2] (1:1) or with [MCl2(NCPh)2] and PPh3 (1:1:2) give complexes [M[eta2-S2C=C[C(O)Me]2]L2] [M = Pt, L2 = 1,5-cyclooctadiene (cod) (1); L2 = bpy, M = Pd (2a), Pt (2b), L = PPh3, M = Pd (3a), Pt (3b)] whereas with MCl2 and QCl (2:1:2) anionic derivatives Q2[M[eta2-S2C=C[C(O)Me]2]2] [M = Pd, Q = NMe4 (4a), Ph3P=N=PPh3 (PPN) (4a'), M = Pt, Q = NMe4 (4b)] are produced. Complexes 1 and 3 react with AgClO4 (1:1) to give tetranuclear complexes [[ML2]2Ag2[mu2,eta2-(S,S')-[S2C=C[C(O)Me]2]2]](ClO4)2 [L = PPh3, M = Pd (5a), Pt (5b), L2 = cod, M = Pt (5b')], while the reactions of 3 with AgClO4 and PPh3 (1:1:2) give dinuclear [[M(PPh3)2][Ag(PPh3)2][mu2,eta2-(S,S')-S2C=C[C(O)Me]2]]]ClO4 [M = Pd (6a), Pt (6b)]. The crystal structures of 3a, 3b, 4a, and two crystal forms of 5b have been determined. The two crystal forms of 5b display two [Pt(PPh3)2][mu2,eta2-(S,S')-[S2C=C[C(O)Me]2]2] moieties bridging two Ag(I) centers.     

Ni(II), Pd(II) and Pt(II) complexes of PNP and PSP tridentate amino-phosphine ligands

The ligands D((CH(2))(2)NHPiPr(2))(2) (D = NH 1, S 2) react with (dme)NiCl(2) or (PhCN)(2)MCl(2) (M = Pd, Pt) to give complexes of the form [D((CH(2))(2)NHPiPr(2))(2)MX]X (X = Cl, I; M = Ni, Pd, Pt) which were converted to corresponding iodide derivatives by reaction with Me(3)SiI. Reaction of 1 or 2 with (COD)PdMeCl affords facile routes to [κ(3)P,N,P-NH((CH(2))(2)NHPiPr(2))(2)PdMe]Cl (8a) and [κ(3)P,S,P-S((CH(2))(2)NHPiPr(2))(2)PdMe]Cl (9a) in high yields. An alternative synthetic approach involves oxidative addition of MeI to a M(0) precursor yielding [κ(3)P,N,P-HN(CH(2)CH(2)NHPiPr(2))(2)NiMe]I (10), [κ(3)P,N,P-HN(CH(2)CH(2)NHPiPr(2))(2)MMe]I (M = Pd 8b Pt 11) and [κ(3)P,S,P-S(CH(2)CH(2)NHPiPr(2))(2)MMe]I (M = Pd 9b, Pt 12). Alternatively, use of NEt(3)HCl in place of MeI produces the species [κ(3)P,N,P-HN(CH(2)CH(2)NHPiPr(2))(2)MH]X (X = Cl, M = Ni 13a, Pd 14a, Pt 16a). The analogs containing 2; [κ(3)P,S,P-S((CH(2))(2)NHPiPr(2))(2)MH]X (M = Pd, X = PF(6)15: M = Pt, X = Br, 17a, PF(6)17b) were also prepared in yields ranging from 74-93%. In addition, aryl halide oxidative addition was also employed to prepare [κ(3)P,N,P-HN(CH(2)CH(2)NHPiPr(2))(2)MC(6)H(4)F]Cl (M = Ni 18, Pd 19) and [κ(3)P,S,P-S((CH(2))(2)NHPiPr(2))(2)Pd(C(6)H(4)F)]Cl (20). Crystal structures of 3a, 4a, 5a, 6a, 8a, 9a, 14b and 16b are reported.     

十二员一氧三氮杂环配合物的研究——Ⅰ.1-氧-4,7,10-三氮杂环十二烷及其含钯加合物的合成、性质和结构

本文对合成的1-氧-4,7,10-三氮杂环十二烷和它的含钯加合物进行了元素、红外、核磁、质谱和热分析;并对加合物做了单晶结构测试。加合物晶体属正交晶系,空间群为P2_12_12_1;晶胞参数为a=10.474(2),b=11.632(2),c=14.674(3),AZ=4。结构的偏离因子R=0.052。加合物中,钯(Ⅱ)与四个氯形成平面四边形配位,以H_2PdCl_4分子存在,冠醚环上的一个N原子与HCl的H~+结合形成铵鎓离子,分子式为NHC_2H_4OC_2H_4N H_2C_2H_4NHC_2H_4C1·H_2PdC1_4·H_20.     

Structural basis for unusually long wavelength charge transfer transitions in complexes [MCl(ECH(2)CH(2)NMe(2))(PR(3))] (E = Te,Se; M = Pt,Pd): experimental results and TD-DFT calculations

A series of new complexes, the blue compounds [PdCl(TeCH(2)CH(2)NMe(2))(PR(3))] (PR(3) = PEt(3), PPr(n)(3), PBu(n)(3), PMe(2)Ph, PMePh(2), PPh(3), PTol(3)) and the red [PtCl(TeCH(2)CH(2)NMe(2))(PR(3))] (PR(3) = PMe(2)Ph, PMePh(2)), were synthesized and studied spectroscopically ((1)H and (31)P NMR, UV/vis) and by cyclic voltammetry. The structures of [PdCl(TeCH(2)CH(2)NMe(2))(PPr(n)(3))] (2b) [PdCl(TeCH(2)CH(2)NMe(2))(PMePh(2))] (2e), [PtCl(TeCH(2)CH(2)NMe(2))(PMePh(2))] (2i), and the related [PtCl(SeCH(2)CH(2)NMe(2))(PEt(3))] (3) were determined crystallographically, revealing a typical pattern of trans-positioned neutral N and P donor atoms in an approximately square planar setting. The molecules 2b, 2e, and 2i were calculated by TD-DFT methodology to understand the origin of the weak (epsilon approximately 200 M(-1) cm(-1)) long-wavelength bands at about 600 nm for Pd/Te complexes such as 2b or 2e, at ca. 460 nm for Pt/Te systems such as 2i, and at about 405 nm for Pt/Se analogues such as 3. These transitions are identified as charge transfer transitions from the selenolato or tellurolato centers to unoccupied orbitals involving mainly the phosphine coligands for the Pt(II) compounds and more delocalized MOs for the Pd(II) analogues. Calculations and electrochemical data were used to rationalize the effects of metal and chalcogen variation.     

Structure of AcMet-Gly and Its Interaction with Palladium(II) Tetraaqua Complex Studied by Electrospray Mass Spectrometry and Density Functional Theory

Introduction Palladium(II) complexes, as a promising artificial metallopeptidase, have been extensively studied for se-lective cleavage of methionine and histidine-containing dipeptides,1-11 oligopeptides12-16 and proteins.16-20 Dipeptides AcMet-aa and AcHis-aa, in which the amino-terminus is protected by acetylation and aa is an amino acid residue, are usually cleaved at the Met-aa and His-aa bond with a modest but significant turn-over.6,7,9 In oligopeptides which contain Met or His or b…     

Preparation and characterization of dinuclear Pd(II) complexes of binucleating tetraaza-thiophenolate ligands

The thioethers 4-tert-butyl-2,6-bis((2-(dimethylamino)ethylimino)methyl)phenyl(tert-butyl)sulfane (tBu-L3) and 4-tert-butyl-2,6-bis((2-(dimethylamino)ethylimino)methyl)phenyl(tert-butyl)sulfane (tBu-L4) react with PdCl2(NCMe)2 to give the dinuclear palladium thiophenolate complexes [(L3)Pd2Cl2]+ (2) and [(L4Pd2(mu-Cl)]2+ (3) (HL3= 2,6-bis((2-(dimethylamino)ethylimino)methyl)-4-tert-butylbenzenethiol, HL4 = 2,6-bis((2-(dimethylamino)ethylamino)methyl)-4-tert-butylbenzenethiol). The chloride ligands in could be replaced by neutral (NCMe) and anionic ligands (NCS-, N3-, CN-, OAc-) to give the diamagnetic Pd(II) complexes [(L3)Pd2(NCMe)2]3+ (4), [(L3)Pd2(NCS)2]+ (5), [(L3)Pd2(N3)2]+ (6), [{(L3)Pd2(mu-CN)}2]4+ (7) and [(L3)Pd2(OAc)]2+ (9). The nitrile ligands in and in [(L3)Pd2(NCCH2Cl)2]3+ are readily hydrated to give the corresponding amidato complexes [(L3)Pd2(CH3CONH)]2+ (8) and [(L3)Pd2(CH2ClCONH)]2+ (10). The reaction of [(L3)Pd2(NCMe)2]3+ with NaBPh4 gave the diphenyl complex [(L3)Pd2(Ph)2]+ (11). All complexes were either isolated as perchlorate or tetraphenylborate salts and studied by IR, 1H and 13C NMR spectroscopy. In addition, complexes 2[ClO4], 3[ClO4]2, 5[BPh4], 6[BPh4], 7[ClO4]4, 9[ClO4]2, 10[ClO4]2 and 11[BPh4] have been characterized by X-ray crystallography.     

Synthesis and reactivity studies of palladium(II) complexes containing the N-phosphorylated iminophosphorane-phosphine ligands Ph2PCH2P{=NP(=O)(OR)2}Ph2 (R=Et, Ph): application to the catalytic synthesis of 2,3-dimethylfuran

Reactions of [PdCl2(COD)] with 1 equiv. of the iminophosphorane-phosphine ligands Ph2PCH2P{=NP(=O)(OR)2}Ph2 (R=Et, Ph) lead to the novel Pd(II) derivatives cis-[PdCl2(kappa2-(P,N)-Ph2PCH2P{=NP(=O)(OR)2}Ph2)] (R=Et, Ph). Pd-N bond cleavage readily takes place upon treatment of these species with a variety of two-electron donor ligands. By this way, complexes cis-[PdCl2(kappa1-(P)-Ph2PCH2P{=NP(=O)(OR)2}Ph2)(L)] (R=Et, L=CNtBu, CN-2,6-C6H3Me2, py, P(OMe)3, P(OEt)3; R=Ph, L=CNtBu, CN-2,6-C6H3Me2, py, P(OMe)3, P(OEt)3) have been synthesized in high yields. The addition of two equivalents of ligands to dichloromethane solutions of [PdCl2(COD)] results in the formation of complexes trans-[PdCl2(kappa1-(P)-Ph2PCH2P{=NP(=O)(OR)2}Ph2)2] (R=Et, Ph), which can be converted into the dicationic species [Pd(Ph2PCH2P{=NP(=O)(OR)2}Ph2)2][SbF6]2 (R=Et, Ph) by treatment with AgSbF6. Complex also reacts with CNtBu to afford trans-[Pd(kappa1(P)-Ph2PCH2P{=NP(=O)(OPh)2}Ph2)2(CNtBu)2][SbF6]2. The structures of and have been determined by single-crystal X-ray diffraction methods. In addition, the ability of these Pd(II) complexes to promote the catalytic cycloisomerization of (Z)-3-methylpent-2-en-4-yn-1-ol into 2,3-dimethylfuran has also been studied.     

Reactivity studies of oxo-Mo(IV) complexes containing potential hydrogen-bond acceptor/donor phenolate ligands

Reactivity studies of oxo-Mo(IV) complexes, Tp(iPr)MoO{2-OC(6)H(4)C(O)R-κ(2)O,O'} (R = Me, Et, OMe, OEt, OPh, NHPh), containing chelated hydrogen-bond donor/acceptor phenolate ligands are reported. Hydrolysis/oxidation of Tp(iPr)MoO(2-OC(6)H(4)CO(2)Ph-κ(2)O,O') in the presence of methanol yields tetranuclear [Tp(iPr)MoO(μ-O)(2)MoO](2)(μ-OMe)(2) (1), while condensation of Tp(iPr)MoO{2-OC(6)H(4)C(O)Me-κ(2)O,O'} and methylamine gives the chelated iminophenolate complex, Tp(iPr)MoO{2-OC(6)H(4)C(Me)NMe-κ(2)O,N} (2), rather than the aqua complex, Tp(iPr)MoO{2-OC(6)H(4)C(Me)NMe-κO}(OH(2)). The oxo-Mo(IV) complexes are readily oxidized by dioxygen or hydrogen peroxide to the corresponding cis-dioxo-Mo(VI) complexes, Tp(iPr)MoO(2){2-OC(6)H(4)C(O)R}; in addition, suitable one-electron oxidants, e.g., [FeCp(2)]BF(4) and [N(C(6)H(4)Br)(3)][SbCl(6)], oxidize the complexes to their EPR-active (g(iso) ≈ 1.942) molybdenyl counterparts (3, 4). Molybdenyl complexes such as Tp(iPr)MoOCl{2-OC(6)H(4)C(O)R} (5) and Tp(iPr)MoOCl(2) also form when the complexes react with chlorinated solvents. The ester derivatives (R = OMe, OEt, OPh) react with propylene sulfide to form cis-oxosulfido-Mo(VI) complexes, Tp(iPr)MoOS{2-OC(6)H(4)C(O)R}, that crystallize as dimeric μ-disulfido-Mo(V) species, [Tp(iPr)MoO{2-OC(6)H(4)C(O)R}](2)(μ-S(2)) (6-8). The crystal structures of [Tp(iPr)MoO(μ-O)(2)MoO](2)(μ-OMe)(2), Tp(iPr)MoO{2-OC(6)H(4)C(Me)NMe}, Tp(iPr)MoOCl{2-OC(6)H(4)C(O)NHPh}·{2-HOC(6)H(4)C(O)NHPh}, and [Tp(iPr)MoO{2-OC(6)H(4)C(O)R}](2)(μ-S(2)) (R = OMe, OEt) are reported.