Some transesterification reactions of [Ir(CO2Me)(CO)2(PPh3)2]

The iridium(I) complex [Ir(CO₂Me)(CO)₂(PPh₃)₂] undergoes a transesterification reaction with the alcohols CH₂C(R)CH₂OH (R = H, Me), MeCCCH₂CH₂OH, and HOCH₂CH₂OH to afford the complexes

[Ir(CO₂CH₂CH₂CMe)(CO)₂(PPh₃)₂] and [Ir(CO₂CH₂CH₂OH)(CO)₂(PPh₃)₂], respectively. In contrast the acetylenic alcohol HCCCH₂CH₂OH gives [Ir(CCCH₂CH₂OH)(CO)PPh₃)₂]. Some reactions of the new complexes are described.     

The uranium-nitrogen bond in U IV complexes supported by the hydrotris(3,5-dimethylpyrazolyl)borate ligand

Insertion of benzonitrile and acetonitrile into the U-C bond of [U(Tp(Me2))Cl(2)(CH(2)SiMe(3))](Tp(Me2)= HB(3,5-Me(2)pz)(3)) gives the ketimide complexes [U(Tp(Me2))Cl(2){NC(R)(CH(2)SiMe(3))}](R = Ph (1); Me (2)). The identity of complex was ascertained by a single-crystal X-ray diffraction study. In the solid state exhibits octahedral geometry with a short U-N bond length to the ketimide ligand. We also report herein the synthesis and the X-ray crystal structures of the uranium amide complexes [U(Tp(Me2))Cl(2)(NR(2))](R = Et (3); Ph (4)). A detailed comparison of the U-N bond lengths in these compounds with other known U-N (and Th-N) distances in amide and ketimide actinide(IV) complexes is performed, confirming the short character of the U-N bond length in 1.     

Reaction of some tertiary phosphines and phosphites with [Co(η5-C5H5)(S2C2{CN}2)]

Reaction of the 16 electron monomer [Co(η⁵-C₅H₅)(S₂C₂{CN}₂)] with various tertiary phosphines and phosphites (L) gives readily the 18 electron monomers [Co(η⁵-C₅H₅)(S₂C₂{CN}₂)L] which for L = P(OR)₃ have J($\text{P}$C₅$\text{H}$₅) ca. 6 Hz but J($\text{P}$C₅$\text{H}$₅) = 0 for L = PR₃.     

The crystal and molecular structure of tetraethylammonium hydrotris(3,5-dimethylpyrazolyl)boratotricarbonylmolybdenum(0), [NEt4][Mo(CO)3HB(C5H7N2)3]

The crystal and molecular structure of tetraethylammonium hydrotris(3,5-dimethylpyrazolyl)boratotricarbonylmolybdenum(0), [N(C₂H₅)₄][Mo(CO)_3^? HB(3,5-Me₂pz)₃] has been determined from intensity data collected using counter methods. The salt crystallizes in space group Pna2₁ with parameters a = 18.038(6), b = 9.956(3), c = 16.881(3) Å, V = 3031.4(20) ų, Z = 4, d_calc = 1.33 g/ml and d_obs = 1.33 g/ml. Final convergence yielded a conventional R = 0.042 and a “goodness of fit” of 2.07. The steric pocket formed by the 3-methyl hydrogens of the pyrazolyl moiety is discussed.     

Chelate complex Ni(S2C2H2)2 as a molecular model of the hydrodesulfurization active center

Electronic states of Ni atom in a square-planar complex Ni(S₂C₂H₂)₂ and its molecular adduct with H₂S were studied by means ofab initio molecular orbital calculations. H₂S adsorption stabilizes the Ni(IV) state (d⁶) in the complex with the Ni atom shifted from the plane by 0.35 ?.     

Synthesis and characterization of methylpalladium(II) dithiolate complexes of the type [PdMe(SS)(ER3)] (SS = S2CNR 2, S2COEt, S2P(OR)2, S2 PPh2; ER3 = PMePh2, PPh3, AsPh3)

Methylpalladium(II) dithiolate complexes of the type [PdMe(SS)(ER₃] (SS = S₂ CNR₂ (R = Me or Et), S₂COEt, S₂P(OR)₂ (R = Et, ⁿPr, ⁱPr), S₂PPh₂; ER₃ = PMePh₂, PPh₃, AsPh₃) have been synthesized by the reaction of [Pd₂Me₂(μ-Cl)₂(PMePh₂)₂] with sodium/potassium/ammonium salts of the dithio acid or by treatment of [PdMeCl(cod)] with ER₃ followed by sodium/potassium/ammonium salts of the dithio ligand. All the complexes were characterized by elemental analysis, IR and nuclear magnetic resonance (¹H, ³¹P) data.     

Studies on (SCN)2M(NCS)2Hg2(p-tolyl)2 and (SCN)2M(NCS)2Hg2(α-naphthyl)2 and their complexes

p-Tolyl mercury thiocyanate and α-naphthyl mercury thiocyanate react with Co(NCS)₂2py and form a bimetallic pink compound of formula (py)₂(SCN)₂Co(NCS)₂Hg₂R₂ (R = p-tolyl and α-naphthyl group). On heating this compound in vacuum a blue compound (SCN)₂Co(NCS)₂Hg₂R₂ is formed. Nickel analogues (SCN)₂Ni(NCS)₂Hg₂R₂ are formed by direct reaction of p-tolyl or α-naphthyl mercury thiocyanate with nickel thiocyanate. (SCN)₂Co(NCS)₂Hg₂R₂ and (SCN)₂Ni(NCS)₂Hg₂R₂ act as Lewis acids and form complexes with bases. The Lewis acids and their complexes with various bases have been characterized by elemental analyses, molar conductance, molecular weight, magnetic moment, infrared and electronic spectral studies. These studies reveal that both the Lewis acids are monomers. In (SCN)₂Co(NCS)₂Hg₂R₂ the CO(II) has tetrahedral geometry, where as in (SCN)₂Ni(NCS)₂Hg₂R₂ the Ni(II) has octahedral geometry through elongated axial bondings with SCN-groups of other molecules. Thiocyanate bridging of the type R-Hg-SCN-M [M = Co(II), Ni(II)] is present in the compounds. Pyridine and dimethylsulphoxide form adducts with these compounds by coordinating at Co(II) or Ni(II). The thiocyanate bridge is retained in these complexes. 2-2′bipyridyl ruptures the thiocyanate bridging in both the Lewis acids and forms cationic-anionic complexes of the type [M(L-L)₃][RHg(SCN)₂]₂. In both the type of complexes Co(II) and Ni(II) possess octahedral environment. The “softness” values have been used in a novel manner in proposing the structure of the complexes.     

Synthesis of U(IV) imidos from Tp*2U(CH2Ph) (Tp* = hydrotris(3,5-dimethylpyrazolyl)borate) by extrusion of bibenzyl

Addition of organic azides, N(3)R (R = 2,4,6-trimethylphenyl (Mes), phenyl (Ph), 1-adamantyl (Ad)), to a solution of the uranium(III) alkyl complex, Tp*(2)U(CH(2)Ph) (Tp* = hydrotris(3,5-dimethylpyrazolyl)borate) (1), results in the formation of a family of uranium(iv) imido derivatives, Tp*(2)U(NR) (2-R). Notably, these complexes were synthesized in high yields by coupling of the benzyl groups to form bibenzyl. The uranium(IV) imido derivatives, 2-Mes, 2-Ph, and 2-Ad, were all characterized by both (1)H NMR and IR spectroscopy, and 2-Mes and 2-Ad were also characterized by X-ray crystallography. In the molecular structure of 2-Mes, typical κ(3)-coordination of the Tp* ligands was observed; however in the case of 2-Ad, one pyrazole ring of a Tp* ligand has rotated away from the metal centre, forcing a κ(2)-coordination of the pyrazoles. This results in a uranium-hydrogen interaction with the Tp* B-H. Treating these imido complexes with para-tolualdehyde results in multiple bond metathesis, forming the terminal uranium(IV) oxo complex, Tp*(2)U(O), and the corresponding imine.     

The reactions of some protected and unprotected monosaccharides with M(NO){HB(3,5-Me2C3HN2)3}X2 (M = Mo, X = Cl, Br, I; M = W, X = Cl)

The reactions between [M(NO){HB(3,5-Me₂C₃HN₂)₃}X₂] (M = Mo, X = Cl, Br, I; M = W, X = Cl) and the monosaccharides 2,3:4,5-di-O-iso-propylidene-β- -fructopyranose, 2,3:5,6-di-O-isopropylidene-- -mannofuranose, methyl-- -glucopyranoside and -(+)-mannofuranose have been investigated and the complexes [M(NO){HB(3,5- Me₂C₃HN₂)₃}X(OR)] (M = Mo, X = Cl, Br, I; M = W, X = Cl; ROH = 2,3:4,5-di-O- isopropylidene-β- -fructopyranose) have been isolated as mixtures of diastereoisomers.     

Reactions of the cycloheptatrienyl complexes [MX(CO)2(η-C7H7)] (M=Mo, X=Br; M=W, X=I) with CNBu: X-ray crystal structure of [WI(CO)2(CNBu)2(η-C7H7)]

Reaction of [MX(CO)₂(η⁷-C₇H₇)] (M=Mo, X=Br; M=W, X=I) with two equivalents of CNBu^t in toluene affords the trihapto-bonded cycloheptatrienyl complexes [MX(CO)₂(CNBu^t)₂(η³-C₇H₇)] (1, M=Mo, X=Br; 2, M=W, X=I). The X-ray crystal structure of 2 reveals a pseudo-octahedral molecular geometry with an asymmetric ligand arrangement at tungsten in which one CNBu^t is located trans to the η³-C₇H₇ ring. Treatment of 2 with tetracyanoethene results in 1,4-cycloaddition at the η³-C₇H₇ ring to give [WI(CO)₂(CNBu^t)₂{η³-C₉H₇(CN)₄}], 3. The principal reaction type of the molybdenum complex 1 is loss of carbonyl and bromide ligands to afford substituted products [MoBr(CNBu^t)₂(η⁷-C₇H₇)] 4 or [Mo(CO)(CNBu^t)₂(η⁷-C₇H₇)]Br. Reaction of [MoBr(CO)₂(η⁷-C₇H₇)] with one equivalent of CNBu^t in toluene at 60°C affords [MoBr(CO)(CNBu^t)(η⁷-C₇H₇)], 5, which is a precursor to [Mo(CO)(CNBu^t)(NCMe)(η⁷-C₇H₇)][BF₄], 6, by reaction with Ag[BF₄] in acetonitrile. In contrast with the parent dicarbonyl systems [MoX(CO)₂(η⁷-C₇H₇)], complexes of the Mo(CO)(CNBu^t)(η⁷-C₇H₇) auxiliary, 5 and 6, do not afford observable η³-C₇H₇ products by ligand addition at the molybdenum centre.     

Synthesis and characterization of isomanolonitrile dithiolato palladium complexes. Crystal structure of (PPh3)2Pd(S2C4N2) and (Et4N)2WS4Pd(S2C4N2)

A series of isomalononitrile dithiolato palladium complexes, (PPh₃)₂Pd(1-mnt) (1), [P(OPh)₃]₂Pd(i-mnt) (2), (PPh₃)(py)Pd(i-mnt)·CH₃CN (4), (Et₄N)₂Pd(i-mnt)₂ (4) and (Ph₄As)₂Pd(i-mnt)₂ (5) were synthesized and characterized by elemental analysis and IR spectroscopy. The reaction between (Et₄N)₂Pd(i-mnt)₂ (4) and (Et₄N)₂WS₄ gave a mixed metal cluster (Et₄N)₂WS₄Pd(i-mnt) (6). The crystallographically determined structures of 1 and 6 are reported.     

Structural and spectroscopic properties of Hexamethylenetetramine cobalt(II) complex: [Co(NCS)2(hmt)2(H2O)2][Co(NCS)2(H2O)4] (H2O)

Synthesis, structure, spectroscopy and thermal properties of complex [Co(NCS)₂(hmt)₂(H₂O)₂][Co(NCS)₂(H₂O)₄] (H₂O) (I), assembled by hexamethylenetetramine and octahedral Co(II) metal ions, are reported. Crystal data for I: F_w 387.34, a=9.020(8), b=12.887(9), c=7.95(1) Å, =96.73(4), β=115.36(5), γ=94.16(4)°, V=820(1) Å³, Z=2, space group=P−1, T=173 K, λ(Mo-K)=0.71070 Å, ρ_calc=1.718567 g cm⁻³, μ=17.44 cm⁻¹, R=0.088, R_w=0.148. An interesting two-dimensional network is assembled via hydrogen bonds through coordinated and free water molecules. The d–d transition energy levels of Co(II) ion are determined by UV–vis spectroscopy and calculated by ligand field theory. The calculated results agree well with experiment ones.     

CO2 fixation by [WIVO(S2C2(CN)2)2]2?: functional model for the tungsten-formate dehydrogenase of Clostridium thermoaceticum

(NEt₄)₂[W^IVO(S₂C₂(CN)₂)₂] (1), isolated by reaction of Na₂ WO₄, Na₂S₂C₂(CN)₂ (Na₂mnt) in acidified (pH5.5) aqueous medium in the presence of excess of sodium dithionite and NEt₄Br, reduces CO₂/HCO ₃ ⁻ (pH 7.5) to yield HCOO⁻ and (NEt₄)₂[W^VIO₂(S₂C₂(CN)₂)₂] (2) mimicking tungsten-formate dehydrogenase (W-FDH) activity. (1) reacts with Na₂MoO₄ in acidic medium to produce [Mo^IvO(S₂C₂(CN)₂)₂]²⁻ implicating the displacement of tungsten by molybdenum from the cofactor complex in W-FDH.     

Synthesis and crystal structure of the heteroleptic lanthanum(III) bis-diphosphinomethanide complex [La{CH(PPh2)2}2(I)(THF)2]

Treatment of CH₂(PPh₂)₂ with n-BuLi/t-BuOK in diethyl ether affords the potassium diphosphinomethanide complex [K{CH(PPh₂)₂}(OEt₂)_0.5] (1) in high yield. Metathesis of two equivalents of 1 with LaI₃(THF)₄ yields the heteroleptic bis-diphosphinomethanide complex [La{CH(PPh₂)₂}₂(I)(THF)₂] (2). X-ray crystallography shows the diphosphinomethanide ligands in 2 adopt different coordination modes in the solid state; one adopts a κ²-PP mode with no La-C contact, and the other adopts an η³-PCP mode, thus giving an eight-coordinate lanthanum centre.     

Qualitative structure of (CO2)2 and (OCS)2

Molecular beam deflection studies on (CO₂)₂ and (OCS)₂ indicate that both these species are polar molecules. Structural implications of this are explored in light of previous studies of these systems.     

A new versatile binuclear seven-coordinate complex of molybdenum(II), [(μ-Cl)2{Mo(μ-Cl)(SnCl3)(CO)3}2]

The two new seven-coordinate anionic complexes of molybdenum(II), binuclear [(μ-Cl)₂{Mo(μ-Cl)(SnCl₃)(CO)₃}₂]²⁻ and mononuclear [MoCl₃(GeCl₃)(CO)₃]²⁻, have been synthesized and characterized by single-crystal X-ray diffraction studies. The binuclear complex exhibits a unique mode of reactivity towards norbornene. In a strictly anhydrous atmosphere the binuclear complex effectively initiates the ring-opening metathesis polymerization reaction of norbornene, but in the presence of water norbornene is efficiently transformed to the binorbornyl ether (C₇H₁₁)₂O.     

镧石型碳酸镨钕向碱式碳酸镨钕的相转变反应特征及其应用

镧石型碳酸镨钕[(PrNd)2(CO3)3·8H2O,LPN]在95℃的不同起始pH值的溶液中陈化不同时间所得样品的XRD衍射图证明了LPN向碱式碳酸镨钕[(PrNd)(OH)(CO3),BPN]的相态转变。为此,详细研究了这一相态转变的反应条件以及粒子特征变化。结果表明:LPN是由片状或条状结晶连生而成的聚集体,具有大的粒度和小的堆密度。当在热的水溶液中陈化时,由于水解反应而发生由LPN向BPN的相转变。这一相转变可以在95℃下pH=7以上的溶液中发生,其转化率随起始溶液pH值的升高和陈化时间的延长而增大。随着相转变的进行,溶液的pH值开始下降明显,而后趋于平缓。相应地,大的团聚体颗粒解散成小的单个粒子,导致粒度减小,分布变窄,氯根含量降低和堆密度的增大。而且,这些变化直接与溶液pH值和陈化时间相关。据此,发展了一种新的制备具有高堆密度、低氯根含量、细粒度和窄分布的新方法,而且通过改变相转变条件可以方便地调谐颗粒特征。     

镧石型碳酸镨钕向碱式碳酸镨钕的相转变反应特征及其应用

本文研究了镧石型碳酸镨钕[（PrNd）₂（CO₃）₃·8H₂O,LPN]在95℃的不同起始pH值的溶液中陈化不同时间所得样品的XRD衍射图,证明所得样品为碱式碳酸镨钕[（PrNd）（OH）（CO₃）,BPN]。为此,详细研究了这一相态转变的反应条件以及粒子特征变化。结果表明：LPN是由片状或条状结晶连生而成的聚集体,具有大的粒度和小的堆密度。当在热的水溶液中陈化时,由于水解反应而发生由LPN向BPN的相转变。这一相转变可以在95℃下pH=7以上的溶液中发生,其转化率随起始溶液pH值的升高和陈化时间的延长而增大。随着相转变的进行,溶液的pH值开始下降明显,而后趋于平缓。相应地,大的团聚体颗粒解散成小的单个粒子,导致粒度减小,分布变窄,氯根含量降低和堆密度的增大。而且,这些变化直接与溶液pH值和陈化时间相关。据此,发展了一种新的制备具有高堆密度、低氯根含量、细粒度和窄分布的新方法,而且通过改变相转变条件可以方便地调谐颗粒特征。     

Spin transition in [Fe(phen)2(NCS)2] and [Fe(bipy)2(NCS)2]: Hysteresis and effect of crystal quality

Detailed magnetic susceptibility measurements on the polycrystalline complexes [Fe(phen)₂(NCS)₂] (phen = 1.10-phenanthroline) and [Fe(bipy)₂(NCS)₂] (bipy = 2,2′-bipyridine) have revealed a narrow hysteresis in both systems indicative of a first-order nature of the spin transition ⁵T_2g(O_h) ? ¹ A_tg(O_h). The crystal quality, in particular crystal defects (through preparation or grinding), have been shown to influence strongly the spin transition behaviour.     

Formation of (η-R5C5)Ru(NO)X2 by the nitrosylation of (η-R5C5)Ru(CO)2X under irradiation

The ruthenium(II) complexes (η-R₅C₅)Ru(CO)₂X with R = H, CH₃ and X = Cl, Br, I undergo a facile reaction with nitric oxide under UV irradiation to afford ruthenium(IV) nitrosyl derivatives of the general type (η-R₅C₅)Ru(NO)X₂.