Nickel(II) complexes of bidentate N-heterocyclic carbene/phosphine ligands: efficient catalysts for Suzuki coupling of aryl chlorides

Nickel(II) complexes of bidentate N-heterocyclic carbene (NHC)/phosphane ligand L were prepared and structurally characterized. Unlike palladium, which forms [PdCl(2)(L)], the stable nickel product isolated is the ionic [Ni(L)(2)]Cl(2). These Ni(II) complexes are highly robust in air. Among different N-substituents on the ligand framework, the nickel complex of ligand L bearing N-1-naphthylmethyl groups (2 a) is a highly effective catalyst for Suzuki cross-coupling between phenylboronic acid and a range of aryl halides, including unreactive aryl chlorides. The activities of 2 a are largely superior to those of other reported nickel NHC complexes and their palladium counterparts. Unlike the previously reported [NiCl(2)(dppe)] (dppe=1,2-bis(diphenylphosphino)ethane), 2 a can effectively catalyze the cross-coupling reaction without the need for a catalytic amount of PPh(3), and this suggests that the PPh(2) functionality of hybrid NHC ligand L can partially take on the role of free PPh(3). However, for unreactive aryl chlorides at low catalyst loading, the presence of PPh(3) accelerates the reaction.     

Ni(PPh3)2Cl2催化2-氯嘧啶与芳基硼酸的Suzuki-Miyaura偶联反应

本文在Ni(PPh3)2 Cl2催化下顺利实现了不同取代基2-氯嘧啶与芳基硼酸的Suzuki-Miyaura偶联反应.实验表明,取代基的电子效应和空间位阻效应对2-氯嘧啶的反应活性影响较小.该反应产率良好,官能团耐受性好,为2-芳基嘧啶衍生物的合成提供了一类简单有效的方法.     

Palladium-catalyzed cross-coupling reactions between dihydropyranylindium reagents and aryl halides. synthesis of C-aryl glycals

[reaction: see text] Palladium(0)-catalyzed cross-coupling reactions between tris(dihydropyranyl)indium 1 and aryl halides 2 have been investigated. Aryl iodides and electron-deficient aryl bromides couple efficiently with the in situ-generated indium reagents in the presence of 1-5 mol % Cl(2)Pd(PPh(3))(2) to produce substituted dihydropyrans 3 with minimal (<10%) dimer (4) formation. Organoindium reagents derived from D-glucal also undergo cross couplings with aryl iodides to produce C-aryl glycals.     

Mononuclear and dinuclear palladium and nickel complexes of phosphinimine-based tridentate ligands

The tridentate bis-phosphinimine ligands O(1,2-C(6)H(4)N=PPh(3))(2)1, HN(1,2-C(2)H(4)N=PR(3))(2) (R = Ph 2, iPr 3), MeN(1,2-C(2)H(4)N=PPh(3))(2)4 and HN(1,2-C(6)H(4)N=PPh(3))(2)5 were prepared. Employing these ligands, monometallic Pd and Ni complexes O(1,2-C(6)H(4)N=PPh(3))(2)PdCl(2)6, RN(1,2-CH(2)CH(2)N=PPh(3))(2)PdCl][Cl] (R = H 7, Me 8), [HN(1,2-CH(2)CH(2)N=PiPr(3))(2)PdCl][Cl] 9, [MeN(1,2-CH(2)CH(2)N=PPh(3))(2)PdCl][PF(6)] 10, [HN(1,2-CH(2)CH(2)N=PPh(3))(2)NiCl(2)] 11, [HN(1,2-CH(2)CH(2)N=PR(3))(2)NiCl][X] (X = Cl, R = iPr 12, X = PF(6), R = Ph 13, iPr 14), and [HN(1,2-C(6)H(4)N=PPh(3))(2)Ni(MeCN)(2)][BF(4)]Cl 15 were prepared and characterized. While the ether-bis-phosphinimine ligand 1 acts in a bidentate fashion to Pd, the amine-bis-phosphinimine ligands 2-5 act in a tridentate fashion, yielding monometallic complexes of varying geometries. In contrast, initial reaction of the amine-bis-phosphinimine ligands with base followed by treatment with NiCl(2)(DME), afforded the amide-bridged bimetallic complexes N(1,2-CH(2)CH(2)N=PR(3))(2)Ni(2)Cl(3) (R = Ph 16, iPr 17) and N(1,2-C(6)H(4)N=PPh(3))(2)Ni(2)Cl(3)18. The precise nature of a number of these complexes were crystallographically characterized.     

Sigma-organyl complexes of ruthenium and osmium supported by a mixed-donor ligand

A series of vinyl, aryl, acetylide and silyl complexes [Ru(R)(kappa2-MI)(CO)(PPh3)2] (R = CH=CH2, CH=CHPh, CH=CHC6H4CH3-4, CH=CH(t)Bu, CH=2OH, C(C triple bond CPh)=CHPh, C6H5, C triple bond CPh, SiMe2OEt; MI = 1-methylimidazole-2-thiolate) were prepared from either [Ru(R)Cl(CO)(PPh3)2] or [Ru(R)Cl(CO)(BTD)(PPh3)2](BTD = 2,1,3-benzothiadiazole) by reaction with the nitrogen-sulfur mixed-donor ligand, 1-methyl-2-mercaptoimidazole (HMI), in the presence of base. In the same manner, [Os(CH=CHPh)(kappa2-MI)(CO)(PPh3)2] was prepared from [Os(CH=CHPh)(CO)Cl(BTD)(PPh3)2]. The in situ hydroruthenation of 1-ethynylcyclohexan-1-ol by [RuH(CO)Cl(BTD)(PPh3)2] and subsequent addition of the HMI ligand and excess sodium methoxide yielded the dehydrated 1,3-dienyl complex [Ru(CH=CHC6H9)(kappa2-MI)(CO)(PPh3)2]. Dehydration of the complex [Ru(CH=CHCPh2OH)(kappa2-MI)(CO)(PPh3)2] with HBF4 yielded the vinyl carbene [Ru(=CHCH=CPh2)(kappa2-MI)(CO)(PPh3)2]BF4. The hydride complexes [MH(kappa2-MI)(CO)(PPh3)2](M = Ru, Os) were obtained from the reaction of HMI and KOH with [RuHCl(CO)(PPh3)3] and [OsHCl(CO)(BTD)(PPh3)2], respectively. Reaction of [Ru(CH=CHC6H4CH3-4)(kappa2-MI)(CO)(PPh3)2] with excess HC triple bond CPh leads to isolation of the acetylide complex [Ru(C triple bond CPh)(kappa2-MI)(CO)(PPh3)2], which is also accessible by direct reaction of [Ru(C triple bond CPh)Cl(CO)(BTD)(PPh3)2] with 1-methyl-2-mercaptoimidazole and NaOMe. The thiocarbonyl complex [Ru(CPh = CHPh)Cl(CS)(PPh3)2] reacted with HMI and NaOMe without migration to yield [Ru(CPh= CHPh)(kappa2-MI)(CS)(PPh3)2], while treatment of [Ru(CH=CHPh)Cl(CO)2(PPh3)2] with HMI yielded the monodentate acyl product [Ru{eta(1)-C(=O)CH=CHPh}(kappa2-MI)(CO)(PPh3)2]. The single-crystal X-ray structures of five complexes bearing vinyl, aryl, acetylide and dienyl functionality are reported.     

Synthesis and characterization of triphenylmethylphosphonium transition metal salts

Triphenylmethylphosphonium salts, [PPh3Me]aMXn (M=Cu2+, Co2+, Mn2+, Ni2+ Fe3+ Pb2+ and Hg2+; X=Cl or I; a=1 or 2 and n=3 or 4) prepared by reacting PPh3MeX with the metal dihalide in EtOH sol-utions, have been characterized by electronic, Raman, far i.r. and Mo¨ssbaur spectra and by their magnetic properties as well as by elemental analyses. The copper complexes [PPh3Me]2CuCl4 and [PPh3Me]2Cu3Cl8 were characterized by X-ray crystallography and the structures are described. Powder diffraction patterns have shown that the cobalt and manganese tetrachloride complexes are isomorphous. Investigation by d.s.c. measurements showed that the complexes exhibit structural phase transitions.     

Mercury bis(phenyltellurolate) as a precursor for the synthesis of binary and ternary nanoclusters

The reaction of Hg(TePh)2 with AgX (X = Cl, NO3) in the presence of PPh3 and PMePh2 in dimethylformamide (DMF) affords the cluster [Hg6Ag4(TePh)16] (1) at room temperature or [Hg6Ag4Te(TePh)14]2 (2) with heating. When Hg(TePh)2 is reacted with [Co(PPh3)2Cl2] or [Ni(PPh3)2Cl2], the clusters [Hg8Te(PhTe)12Cl4]Q [3; Q = [Co(DMF)6]2+ (3a), [Ni(DMF)6]2+ (3b)] are formed. The syntheses of 1 and 2 occur with the incorporation of AgI into the cluster, and the single-crystal analyses show that the two ternary clusters consist of Hg, Ag, and Te centers occupying well-defined positions. Compounds 3a and 3b do not show the incorporation of the metal into the cluster, but the CoII and NiII salts provide the Cl atom to generate the anionic cluster 3 stabilized by the [Co(DMF)6]2+ or [Ni(DMF)6]2+ ion.     

Modified palladium-catalyzed Sonogashira cross-coupling reactions under copper-, amine-, and solvent-free conditions

[reaction: see text] PdCl2(PPh3)2 combined with TBAF under solvent-free conditions provided general and fast Sonogashira cross-coupling reactions of aryl halides with terminal alkynes. In particular, this protocol could be applied to the reactions of deactivated aryl chlorides. In the presence of 3 mol % of PdCl2(PPh3)2 and 3 equiv of TBAF, a number of ArX species (X = I, Br, Cl) were coupled with alkynes to afford the corresponding products in moderate to excellent yields under copper-, amine-, and solvent-free conditions.     

Eta 1 and eta 2 Coordination of 1-amino-closo-dodecaborate

The reaction of the sodium salt of 1-amino-closo-dodecaborate [Na]2[NH2-B12H11] ([Na]2[1]) with [Au(PPh3)Cl] and [Ni(THF)2(Br)2] led to eta 1(N) coordination of 1in [Na][Au(PPh3)(NH2-B12H11)] (2) and [Na]6[Ni(NH2-B12H11)4] (3), respectively. Furthermore, eta 2(N,BH) coordination of was found in [MePPh3][Rh(PPh3)2(NH2-B12H11)] (4), which was synthesized by the reaction of [MePPh3][Na][1] with [Rh(PPh3)3Cl]. All compounds were characterized by single crystal X-ray diffraction and heteronuclear NMR spectroscopy.     

Direct observation of fine structure transitions in a paramagnetic nickel(II) complex using far-infrared magnetic spectroscopy: a new method for studying high-spin transition metal complexes

Novel far-infrared (FIR) absorption spectroscopy in conjunction with multiple, fixed external magnetic fields (FIR magnetic spectroscopy, FIRMS) has been used to investigate pseudotetrahedral complexes with the formula M(PPh(3))(2)Cl(2) (M = Ni, Zn; Ph = C(6)H(5)). Crystal structures have been reported for the Ni complex; we report the structure of the Zn complex. Transmission spectra at 5 K of Ni(PPh(3))(2)Cl(2) (S = 1) at zero magnetic field exhibit absorption bands at 11.41, 15.28, and 23.0 cm(-1). The two lower frequency bands show great sensitivity to external magnetic field, and their field dependence is as expected for electron spin transitions allowing precise determination of the following parameters: |D| = 13.35(1) cm(-1), |E| = 1.93(1) cm(-1), g(x,y) = 2.20(1), g(z) = 2.00(1). Corresponding spectra of Zn(PPh(3))(2)Cl(2) (S = 0) exhibit bands only at >20 cm(-1), which show no field dependence. FIRMS is a promising technique for direct investigation of the electronic structure of high-spin transition metal complexes.     

Oxidative addition of aryl halides: routes to mono- and dimetallic nickel amino-bis-phosphinimine complexes

Oxidative addition of an aryl-halide to Ni(COD)(2) in the presence of an equivalent of amino-bis-phosphinimine ligand affords complexes of the form [HN(CH(2)CH(2)N=PPh(3))(2)Ni-Ar][X] (Ar = C(6)H(4)F, C(6)H(5), X = Cl, Br) while the analogous reactions with 2 equivalents of Ni yield the amido-bridged complexes N(CH(2)CH(2)N=PPh(3))Ni(2)Br(3) and N(1,2-C(6)H(4)N=PPh(3))Ni(2)Br(3).     

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.     

Iridium(III) complexes formed by O-H and/Or C-H activation of 2-(arylazo)phenols

Reaction of 2-(arylazo)phenols with [Ir(PPh(3))(3)Cl] in refluxing ethanol in the presence of a base (NEt(3)) affords complexes of three different types, viz. [Ir(PPh(3))(2)(NO-R)(H)Cl] (R = OCH(3), CH(3), H, Cl and NO(2)), [Ir(PPh(3))(2)(NO-R)(H)(2)] and [Ir(PPh(3))(2)(CNO-R)(H)]. Structures of the [Ir(PPh(3))(2)(NO-Cl)(H)Cl], [Ir(PPh(3))(2)(NO-Cl)(H)(2)] and [Ir(PPh(3))(2)(CNO-Cl)(H)] complexes have been determined by X-ray crystallography. In the [Ir(PPh(3))(2)(NO-R)(H)Cl] and [Ir(PPh(3))(2)(NO-R)(H)(2)] complexes, the 2-(arylazo)phenolate ligands are coordinated to the metal center as monoanionic bidentate N,O-donors, whereas in the [Ir(PPh(3))(2)(CNO-R)(H)] complexes, they are coordinated to iridium as dianionic tridentate C,N,O-donors. In all three products formed in ethanol, the two PPh(3) ligands are trans. Reaction of 2-(arylazo)phenols with [Ir(PPh(3))(3)Cl] in refluxing toluene in the presence of NEt(3) affords complexes of two types, viz. [Ir(PPh(3))(2)(CNO-R)(H)] and [Ir(PPh(3))(2)(CNO-R)Cl]. Structure of the [Ir(PPh(3))(2)(CNO-Cl)Cl] complex has been determined by X-ray crystallography, and the 2-(arylazo)phenolate ligand is coordinated to the metal center as a dianionic tridentate C,N,O-donor and the two PPh(3) ligands are cis. All of the iridium(III) complexes show intense MLCT transitions in the visible region. Cyclic voltammetry shows an Ir(III)-Ir(IV) oxidation on the positive side of SCE and an Ir(III)-Ir(II) reduction on the negative side for all of the products.     

Synthesis of Ge2NiS4 clusters and the thermal transformation to a Ge4Ni6S12 cluster

The reaction of Ni(dppe)Cl2 and syn-[DmpGe(SLi)(mu-S)2Ge(SLi)Dmp] prepared in situ from syn-[DmpGe(SH)(mu-S)2Ge(SH)Dmp] (1) and n-BuLi (2 equiv) afforded the Ge2NiS4 cluster, [DmpGe(mu-S)]2(mu-S)2Ni(dppe) (2) (Dmp = 2,6-dimesitylphenyl). The nickel in 2 assumes a slightly distorted square planar geometry. However, another Ge2NiS4 cluster, [DmpGe(mu-S)]2(mu-S)2Ni(PPh3)2 (3) obtained from a similar reaction with Ni(PPh3)2Cl2, contains the nickel in a tetrahedron. When 3 was heated to 120 degrees C in toluene, a novel Ge4Ni6S12 cluster [DmpGe(mu-S)3]4Ni6 (5) was obtained. In cluster 5, six nickels form an octahedron with the nickels occupying its vertexes, and four DmpGeS3 units cap half of the trigonal faces.     

Role of cyclometalation in controlling the rates of ligand substitution at platinum(II) complexes

The rates of chloride for triphenylphosphine substitution have been measured in dichloromethane for a series of cyclometalated [Pt(N-N-C)Cl] complexes containing a number of terdentate N-N-C anionic ligands, derived from deprotonated alkyl-, phenyl-, and benzyl-6-substituted 2,2'-bipyridines. These rates have been compared with those of the corresponding [Pt(N-N)(C)Cl] (N-N = 2,2'-bipyridine; C = CH3 or C6H5) complexes having the same set of donor atoms but less constrained arrangements of the ligands. The reactions of the cyclometalated compounds occur as a single-stage conversion from the substrate to the ionic pair [Pt(N-N-C)(PPh3)]Cl products. There is no evidence by 1H and 31P(1H) NMR spectroscopy for the formation of other Pt(II) species or of concurrent ring-opening processes. In contrast, in the monoalkyl- or monoaryl-2,2'-bipyridine complexes, chloride substitution is followed by subsequent slower processes which involve the detachment of one arm of the chelated 2,2'-bipyridine, fast cis to trans isomerization of the cis-[Pt(PPh3)2(eta 1-bipy)(R)]+ transient intermediate, and, eventually, the release of free bipy, yielding trans-[Pt(PPh3)2(R)Cl] (R = Me or Ph). All reactions are first-order with respect to complex and phosphine concentration, obeying the simple rate law kobsd = k2[PPh3]. The values of the second-order rate constant k2 do not seem particularly sensitive to the nature of the bonded organic moiety (alkyl or aryl), to its structure (cyclometalated or not), to the size of the ring, or to the number of alkyl substituents on it. The effects are those foreseen on the basis of an associative mode of activation. The only exception to this pattern of behavior is constituted by the complex [Pt(bipy phi-H)Cl] (bipy phi = 6-phenyl-2,2'-bipyridine), which features a significant rate enhancement with respect to the analogue [Pt(bipy)(Ph)Cl] complex. The results of this work, together with those of a previous paper, suggest that there is not a specific role of cyclometalation in controlling the reactivity, unless an in-plane aryl ring becomes part of the pi-acceptor system of the chelated 2,2-bipyridine, behaving as a cyclometalated analogue of the nitrogen terdentate 2,2':6',2"-terpyridine.     

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.     

有机金配合物催化的胺羰化制氨基甲酸酯及酰胺

使用一系列有机金配合物HAuCl4、Au(PPH3)Cl、Au(PPh3)2Cl、Au(PPh3)NO3和[Au(PPh3)]2S,催化胺类化合物羰化合氨基甲酸酯和酰胺。其中,Au(PPh3)Cl在合成氨基甲酸酯的反应中催化性能最好,而在合成酰胺的反应中[Au(PPh3)]2S的催化性能最好,两者均优于Pd(PPh32)2Cl2催化剂。     

Nickel-catalyzed cross-coupling reaction of grignard reagents with alkyl halides and tosylates: remarkable effect of 1,3-butadienes

A new method for the cross-coupling reaction of Grignard reagents with alkyl chlorides, bromides, and tosylates has been developed by the use of a nickel catalyst in the presence of a diene as an additive. This reaction proceeds efficiently at 0-25 degrees C in THF using primary and secondary alkyl and aryl Grignard reagents. Nickel complexes bearing no phosphine ligands, such as NiCl2, Ni(acac)2, and Ni(COD)2, afford the coupling products in good yields, whereas NiCl2(PPh3)2 and NiCl2(dppp) were less effective. 1,3-Butadiene shows the highest activity as an additive for the present coupling reaction. A plausible reaction pathway was proposed.     

Chemical control on the coordination mode of benzaldehyde semicarbazone ligands. synthesis, structure, and redox properties of ruthenium complexes

Reaction of benzaldehyde semicarbazone (HL-R, where H is a dissociable proton and R is a substituent (R = OMe, Me, H, Cl, NO(2)) at the para position of the phenyl ring) with [Ru(PPh(3))(3)Cl(2)] and [Ru(PPh(3))(2)(CO2)Cl2] has afforded complexes of different types. When HL-NO(2) and [Ru(PPh(3))(3)Cl2] react in solution at ambient temperature, trans-[Ru(PPh(3))(2)(L-NO2Cl] is obtained. Its structure determination by X-ray crystallography shows that L-NO2 is coordinated as a tridentate C,N,O-donor ligand. When reaction between HL-NO2 and [Ru(PPh(3))(3)Cl2] is carried out in refluxing ethanol, a more stable cis isomer of [Ru(PPh(3))(2)(L-NO2)Cl] is obtained. The trans isomer can be converted to the cis isomer simply by providing appropriate thermal energy. Slow reaction of HL-R with [Ru(PPh(3))(2)(CO2)Cl2] in solution at ambient temperature yields 5-[Ru(PPh(3))(2)(L-R)(CO)Cl] complexes. A structure determination of 5-[Ru(PPh(3))(2)(L-NO2)(CO)Cl] shows that the semicarbazone ligand is coordinated as a bidentate N,O-donor, forming a five-membered chelate ring. When reaction between HL-R and [Ru(PPh(3))(2)(CO2Cl2] is carried out in refluxing ethanol, the 4-[Ru(PPh(3))(2)(L-R)(CO)Cl] complexes are obtained. A structure determination of 4-[Ru(PPh(3))(2)(L-NO2)(CO)Cl] shows that a semicarbazone ligand is bound to ruthenium as a bidentate N,O-donor, forming a four-membered chelate ring. All the complexes are diamagnetic (low-spin d(6), S = 0). The trans- and cis-[Ru(PPh(3))(2)(L-NO2)Cl] complexes undergo chemical transformation in solution. The 5- and 4-[Ru(PPh(3))(2)(L-R)(CO)Cl] complexes show sharp NMR signals and intense MLCT transitions in the visible region. Cyclic voltammetry of the 5-[Ru(PPh(3))(2)(L-R)(CO)Cl] and 4-[Ru(PPh(3))(2)(L-R)(CO)Cl] complexes show the Ru(II)-Ru(III) oxidation to be within 0.66-1.07 V. This oxidation potential is found to linearly correlate with the Hammett constant of the substituent R.     

有机金催化胺氧化羰化制氨基甲酸酯

自Haruta等报道高分散担载金催化剂对CO有良好的低温水除活性以来,金催化剂的研究开发开始受到关注,各种提载型金催化剂在选择氧化、氮氧化物消除、选择加氢、甲烷完全氧化以及均相有机金配合物催化剂在醇醛缩合、烯烃羰化、锡烷的偶联等反应中均取得了相当好的效果,但与Pt和Pd等贵金属相比,金作为具有潜在多种催化能力的催化材料了解尚少。现在工业上主要使用胺类化合物与剧毒的光气反应制取异氰酸酯,该反应造成设备腐蚀和环境污染,因此用胺类化合物氧化羰化或硝基化合物的还原羰化合成氨基甲酸酯,然后热裂解制取相应的异氰酸酯得到广泛研究,过去主要以含氮配体配位的钯催化剂为代表的贵金属为催化剂催化羰化合成氨基甲酸酯,以有机金配合物作为含氮化合物羰化催化剂的研究则未见报道,本文首次将有机金配合物作为胺类化合物氧化羰化制取氨基甲酸酯的催化剂,取得了与钯催化剂相当的催化效果,反应如下：R（NH2）n CO O2 R^1OH[Au(PPh3)x]yZ／→／PPh3R(NHCO2R^1)n H2O R=Ar-,RCH2-;R^1=CH3-,CH3CH2-;n=1 or 2,x=1 or 2,y=1 or 2;Z=cl,NO3,S。