Synthesis of a uranium(VI)-carbene: reductive formation of uranyl(V)-methanides, oxidative preparation of a [R2C═U═O]2+ analogue of the [O═U═O]2+ uranyl ion (R = Ph2PNSiMe3), and comparison of the nature of U(IV)═C, U(V)═C, and U(VI)═C double bonds

We report attempts to prepare uranyl(VI)- and uranium(VI) carbenes utilizing deprotonation and oxidation strategies. Treatment of the uranyl(VI)-methanide complex [(BIPMH)UO(2)Cl(THF)] [1, BIPMH = HC(PPh(2)NSiMe(3))(2)] with benzyl-sodium did not afford a uranyl(VI)-carbene via deprotonation. Instead, one-electron reduction and isolation of di- and trinuclear [UO(2)(BIPMH)(μ-Cl)UO(μ-O){BIPMH}] (2) and [UO(μ-O)(BIPMH)(μ(3)-Cl){UO(μ-O)(BIPMH)}(2)] (3), respectively, with concomitant elimination of dibenzyl, was observed. Complexes 2 and 3 represent the first examples of organometallic uranyl(V), and 3 is notable for exhibiting rare cation-cation interactions between uranyl(VI) and uranyl(V) groups. In contrast, two-electron oxidation of the uranium(IV)-carbene [(BIPM)UCl(3)Li(THF)(2)] (4) by 4-morpholine N-oxide afforded the first uranium(VI)-carbene [(BIPM)UOCl(2)] (6). Complex 6 exhibits a trans-CUO linkage that represents a [R(2)C═U═O](2+) analogue of the uranyl ion. Notably, treatment of 4 with other oxidants such as Me(3)NO, C(5)H(5)NO, and TEMPO afforded 1 as the only isolable product. Computational studies of 4, the uranium(V)-carbene [(BIPM)UCl(2)I] (5), and 6 reveal polarized covalent U═C double bonds in each case whose nature is significantly affected by the oxidation state of uranium. Natural Bond Order analyses indicate that upon oxidation from uranium(IV) to (V) to (VI) the uranium contribution to the U═C σ-bond can increase from ca. 18 to 32% and within this component the orbital composition is dominated by 5f character. For the corresponding U═C π-components, the uranium contribution increases from ca. 18 to 26% but then decreases to ca. 24% and is again dominated by 5f contributions. The calculations suggest that as a function of increasing oxidation state of uranium the radial contraction of the valence 5f and 6d orbitals of uranium may outweigh the increased polarizing power of uranium in 6 compared to 5.     

Investigating the role of the outer-coordination sphere in [Ni(P(Ph)2N(Ph‑R)2)2]2+ hydrogenase mimics

A series of dipeptide substituted nickel complexes with the general formula, [Ni(P(Ph)(2)N(NNA-amino acid/ester)(2))(2)](BF(4))(2), have been synthesized and characterized (P(2)N(2) = 1,5-diaza-3,7-diphosphacyclooctane, and the dipeptide consists of the non-natural amino acid, 3-(4-aminophenyl)propionic acid (NNA), coupled to amino acid/esters = glutamic acid, alanine, lysine, and aspartic acid). Each of these complexes is an active electrocatalyst for H(2) production. The effects of the outer-coordination sphere on the catalytic activity for the production of H(2) were investigated; specifically, the impact of sterics, the ability of the side chain or backbone to protonate and the pK(a) values of the amino acid side chains were studied by varying the amino acids in the dipeptide. The catalytic rates of the different dipeptide substituted nickel complexes varied by over an order of magnitude. The amino acid derivatives display the fastest rates, while esterification of the terminal carboxylic acids and side chains resulted in a decrease in the catalytic rate by 50-70%, implicating a significant role of protonated sites in the outer-coordination sphere on catalytic activity. For both the amino acid and ester derivatives, the complexes with the largest substituents display the fastest rates, indicating that catalytic activity is not hindered by steric bulk. These studies demonstrate the significant contribution that the outer-coordination sphere can have in tuning the catalytic activity of small molecule hydrogenase mimics.     

(C60)2Ru2Cl4[Ph2P(CH2)4PPh2]配合物的合成

在氮气氛中采用配体取代法合成了C60以σ-π配位方式与Ru形成的稳定η2型富勒烯双核钌金属配合物(C60)2Ru2Cl4[Ph2P(CH2)4PPh2],其结构经UV,IR,XPS,XRD和元素分析表征.     

Ligand-centred coupling of the alkynyl radical cations [Mo(CCR)(Ph2PCH2CH2PPh2)(η-C7H7)]+ (R = Ph or Bun: crystal structure of the dimeric product [Mo2(Ph2PCH2CH2PPh2)2(η-C7H7)2(μ-C4R2)][PF6]2 (R = Ph)

The radical cations [Mo(CCR)(dppe)(η-C₇H₇)]⁺ (R = Ph or Buⁿ); dppe = Ph₂PCH₂CH₂PPh₂) undergo coupling at C_β of the alkynyl ligand to afford the divinylidene-bridged, dimeric products [Mo₂(dppe)₂(η-C₇H₇)₂(μ-C₄R₂)]²⁺, characterised crystallographically for R = Ph.     

Synthesis of molecular ferromagnetics [R3R′X]MCr(C2O4)3 (X = N,R = Bun,R′ = Prn,Et, Me; X = P,R = Ph,R′ = Bun; M = Mn,Fe, Co,Ni, Cu)

The synthesis, IR spectra, and the temperatures of the transition into a ferromagnetic state (T _c) of layered ferromagnetics [R₃RX[MCr(C₂O₄)₃ (M = Mn, Fe, Co, Cu, and Ni) with the [Ph₃BuP]⁺, [Bu₃RN]⁺ (R = Pr, Et, and Me) cations capable of subsequently changing the distances between metallooxalate layers have been considered. The temperatureT _c has been found to be independent of the size of the organic cation. It is believed that the determining factors in the transition to a ferromagnetic state are exchange interactions inside the metallooxalate layer.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2327–2330, September, 1996.     

Synthesis and structure of gold complexes [Ph3PR]+[Au(CN)2I2-trans]−, R = Et,CH2Ph,Ph

Russian Chemical Bulletin - Gold complexes [Ph3PR]+[Au(CN)2I2-trans]?, where R = Et (1), CH2Ph (2), Ph (3), were synthesized by the reaction of potassium dicyanodiiodoaurate with...     

The formation of alkyne and alkynyl complexes by reaction of 1-alkynes with trans-[M(N2)2(PH2PCH2CH2PPh2)2] (M  Mo OR W) and with [Mo(Ph2PCH2PPh2)3]: X-ray structure of trans-[Mo(CCPh)2(PH2PCH2CH2PPh2)2]

Reaction of RCCH (R  Ph, CO₂Meor CO₂Et) with trans-[M(N₂)₂(dppe)₂] (M  Mo or W; dppe  Ph₂PCH₂CH₂PPh₂) or [Mo(dppm)₃] (dppm  Ph₂PCH₂PPh₂) gives the alkyne complexes [M(RCCH)₂(diphos)₂] (diphos  dppe, M  Mo, R = Ph; dihpos  dppm, M  Mo, R  Ph or CO₂Me) and the alkynyl complexes trans-[M(cCR)₂(dppe)₂], [MH₂(CCR)₂ (dppe)₂] (M  Mo or W. R  Ph, CO₂Me or CO₂Et) and cis-[WH(CCCO₂Me)(dppe)₂]: the X-ray structure of trans-[Mo(CCPh)₂(dppe)₂] is reported.     

New routes to carbonyl complexes of general formula [RuCl2(CO)(S)(PPh3)2] (S = DMA,DMF, DMSO): crystal structure of [RuCl2(CO)(DMA)(PPh3)2] · 1/2CH2Cl2

The compound [RuCl₂(CO)(DMA)(PPh₃)₂] [DMA = dimethylacetamide] was obtained from [RuCl₃(PPh₃)₂-(DMA)] · DMA and CO in DMA. Orange crystals of [RuCl₂(CO)(DMA)(PPh₃)₂] · 1/2CH₂Cl₂ were isolated by slow evaporation of a CH₂Cl₂/DMA solution and its structure was determined by single crystal X-ray diffraction. The analogous compounds containing DMF and DMSO were obtained from the precursor ttt-[RuCl₂(CO)₂(PPh₃)₂]. Characterization of the other complexes is based on i.r. and n.m.r. spectroscopy, including ³¹P{¹H} data.     

H2C[P(Ph)2AUX]2和HC[P(Ph)2AUX]3(X=I,CI)型配合物的构象和Au (I)-Au(I)相互作用的从头算研究

根据配合物H₂C[P(Ph)₂AUX]₂(X=I,CI)和HC[P(Ph)₂AUX]₃(X=I,CI)的晶体结构对它们进行了从头算研究,在MP2近似水平下得到绕C-P旋转所产生构象的势能曲线,从而揭示AU(I)－AU(I)相互作用. 计算结果表明,在所研究的四个配合物中均存在AU(I)-AU(I)相互作用,该作用较弱,约为10. 0～16. 5kJ/mol,与Schmibaur的实验估计值和Pyykko等对其它模型配合物的计算结果接近.     

The synthesis and spectral properties of the novel monodentate(s) coordinated thiosemicarbazide and thiosemicarbazone complexes [Fe(CO)2L(η5-C5H5)][PF6] (L = H2NNHCSNH2, cy-C5H10CNNHCSNH2 or R′R″CNNHCSNH2, R′ = R″ = Me; R′= H,R″ = Ph; R′= H,R″ = p-NO2Ph,R′= Me,R″ = p-MePh)

The acetone complex [Fe(CO)₂(Me₂CO)(η⁵-C₅H₅)][PF₆] reacts with L (L = H₂NNHCSNH₂, cy-C₅H₁₀CNNHCSNH₂, or R′R″CNNHCSNH₂ where R′ = R″ = Me; R′ = H, R″ = Ph; R′ = H, R″ = p-NO₂Ph; R′ = p-MePh) in refluxing trichloromethane to give the new complexes [Fe(CO)₂L(η⁵-C₅H₅)][PF₆]. The complexes are clearly coordinated through the sulphur atom since the thiosemicarbazide complex reacts with benzaldehyde to afford the corresponding thiosemicarbazone compound.     

Reactions of [WI2(CO)(NCMe)(η2-RC2R)2] (R = Me or Ph) with carbon monoxide to give either [WI2(CO)2(η2-MeC2Me)2] or [W(-I) I(CO) (η2-PhC2Ph)2]2. Crystal structure of [WI2(CO) 2( η2-MeC2Me)2]

The complexes [WI₂(CO)(NCMe)(η2)-RC₂R)₂] (R = Me and Ph) react in CH₂Cl₂ with an excess of carbon monoxide to give initially the acetonitrile substituted products [WI₂(CO)₂(η²-RC₂R) ₂]. For R= Me, the complex [WI₂(CO)₂(η²- MeC₂Me)₂] (1) was isolated and its structure determined by X-ray crystallography. However, for R = Ph, dimerisation occurs to give the iodide-bridged compound [W(μ-I)I(CO)(η²-PhC₂Ph)₂]₂ (2) with loss of carbon monoxide. These reactions are reversible as 1 and 2 react with acetonitrile to give [WI₂(CO)(NCMe)(η²-RC₂R)₂]. The ¹³C NMR spectra of I and 2 indicate that the two alkyne ligands donate a total of six electrons to the tungsten in these complexes.     

配合物[Fe(CO)3(PPh2R)2(HgCl2)] (R=pym,fur, py,thi)的Fe-Hg相互作用及31P化学位移

In order to study the effects of R group on Fe-Hg interactions and 31P chemical shifts, the structures of mononuclear complexes Fe(CO)3(PPh2R)2 (R=pym: 1, fur: 2, py: 3, thi: 4; pym=pyrimidine, fur=furyl, py=pyridine, thi=thiazole) and binuclear complexes [Fe(CO)3(PPh2R)2(HgCl2)] (R=pym: 5, fur: 6, py: 7, thi: 8) were studied by using the density functional theory (DFT) PBE0 method. The 31P chemical shifts were calculated by PBE0-GIAO method. Nature bond orbital (NBO) analyseswere also performed to explain the nature of the Fe-Hg interactions. The conclusions can be drawn as follows: (1) The complexes with nitrogen donor atoms are more stable than those with O or S atoms. The more N atom there are, the higher is the stabilitity of the complex. (2) The Fe-Hg interactions play a dominant role in the stabilities of the complexes. In 5 or 6, there is a σ-bond between Fe and Hg atoms, However, in 7 and 8, the Fe-Hg interations act as σP-Fe→nHg and σC-Fe→nHg delocalization. (3) Through Fe邛Hg interactions, there is charge transfer from R groups towards the P, Fe, and Hg atoms, which increases the electron density on P nucleus in binuclear complexes. As a result, compared with their mononuclear complexes, the 31P chemical shifts in binuclear complexes show some reduction.     

Synthesis and structures of mercury and cadmium complexes: [Ph4Sb] 2 + [Hg2I6]2−·Ph2Hg, [Ph4Sb] 2 + [E2I6]2− (E = Hg, Cd), and [Ph4Sb] 2 + [Hg4I10]2−

The reaction of pentaphenylantimony with mercury iodide affords the ionic complex [Ph₄Sb] ₂ ⁺ [Hg₂I₆]^2?·Ph₂Hg (I). The [Ph₄Sb] ₂ ⁺ [Hg₂I₆]^2? (II) and [Ph₄Sb] ₂ ⁺ [Cd₂I₆]^2? (III) complexes are synthesized from tetraphenylantimony iodide and mercury and cadmium iodides. The [Ph₄Sb] ₂ ⁺ [Hg₄I₁₀]^2? complex (IV) is prepared from tetraphenylantimony 2,4-dimethylbenzenesulfonate and mercury iodide. According to the X-ray diffraction data, the Sb atom in the [Ph₄Sb]⁺ cations of complex I has virtually ideal tetrahedral coordination (the CSbC angles are 108.09°–109.64°). In the central square fragment Hg₂I₂ of the [Hg₂I₆]^2? anion, the Hg-I_br bond lengths are 2.825 and 3.075 Å, and the terminal iodine atoms are more strongly bonded to the mercury atoms (Hg-I_term 2.691 and 2.700 Å). The [Cd₂I₆]^2? anion in complex III has a similar structure (the Cd-I_bridg and Cd-I_term distances are 2.865, 2.872 and 2.723, 2.748 Å, respectively). The anions in complex IV are joined by I…Hg (3.651 Å) and I…I (4.058 Å) interactions into an infinite dimeric network.     

Photochemical reactions of [(η 5-C5H5)Mn(CO)3] with Ph2P(S)(CH2) n P(S)Ph2 [n=1, dppm(S)2; 2, dppe(S)2; 3, dppp(S)2]

Six new complexes, Mn(CO)( ⁵-C₅H₅){Ph₂P(S)(CH₂) _n P(S)Ph₂}] (1a–3a) [(1a), n=1; (2a), n=2; (3a), n=3] and [Mn₂(CO)₄( ⁵-C₅H₅)₂(cis--Ph₂P(S)(CH₂) _n P(S)Ph₂)] (1b–3b) [(1b), n=1; (2b), n=2; (3b), n=3] have been synthesized by the photochemical reaction of [( ⁵-C₅H₅)Mn(CO)₃] with Ph₂P(S)(CH₂) _n P(S)Ph₂ [n=1, dppm(S)₂; 2, dppe(S)₂; 3, dppp(S)₂]. The complexes have been characterized by elemental analysis, mass spectroscopy, f.t.-i.r. and ³¹P–[¹H]-n.m.r. spectroscopy. The spectroscopic studies reveal that coordination of the ligand iscis-chelate bidentate in [Mn(CO)( ⁵-C₅H₅){Ph₂P(S)(CH₂) _n P(S)Ph₂}] (1a–3a) and cis-bridging bidentate between two metals in [Mn₂(CO)₄( ⁵-C₅H₅)₂(cis--Ph₂P(S)(CH₂) _n P(S)Ph₂)] (1b–3b).     

Electrochemical and Theoretical Investigations of the Role of the Appended Base on the Reduction of Protons by [Fe(2) (CO)(4) (κ(2) -PNP(R) )(μ-S(CH(2) )(3) S] (PNP(R) ={Ph(2) PCH(2) }(2) NR, R=Me, Ph)

The behavior of [Fe(2) (CO)(4) (κ(2) -PNP(R) )(μ-pdt)] (PNP(R) =(Ph(2) PCH(2) )(2) NR, R=Me (1), Ph (2); pdt=S(CH(2) )(3) S) in the presence of acids is investigated experimentally and theoretically (using density functional theory) in order to determine the mechanisms of the proton reduction steps supported by these complexes, and to assess the role of the PNP(R) appended base in these processes for different redox states of the metal centers. The nature of the R substituent of the nitrogen base does not substantially affect the course of the protonation of the neutral complex by CF(3) SO(3) H or CH(3) SO(3) H; the cation with a bridging hydride ligand, 1?μH(+) (R=Me) or 2?μH(+) (R=Ph) is obtained rapidly. Only 1?μH(+) can be protonated at the nitrogen atom of the PNP chelate by HBF(4) ?Et(2) O or CF(3) SO(3) H, which results in a positive shift of the proton reduction by approximately 0.15?V. The theoretical study demonstrates that in this process, dihydrogen can be released from a η(2) -H(2) species in the Fe(I) Fe(II) state. When R=Ph, the bridging hydride cation 2?μH(+) cannot be protonated at the amine function by HBF(4) ?Et(2) O or CF(3) SO(3) H, and protonation at the N atom of the one-electron reduced analogue is also less favored than that of a S atom of the partially de-coordinated dithiolate bridge. In this situation, proton reduction occurs at the potential of the bridging hydride cation, 2?μH(+) . The rate constants of the overall proton reduction processes are small for both complexes 1 and 2 (k(obs) ≈4-7?s(-1) ) because of the slow intramolecular proton migration and H(2) release steps identified by the theoretical study.     

A study of zinc complexes of the metalloligand [Pt2(μ-S)2(PPh3)4] of the type [Pt2(μ-S)2(PPh3)4ZnL]+ (L = bidentate chelating ligand)

Reactions of [Pt₂(μ-S)₂(PPh₃)₄] with zinc acetate and an ancillary chelating ligand L (HL = 8-hydroxyquinoline, 8-tosylaminoquinoline or maltol) with added trimethylamine in methanol give new cationic platinum–zinc sulfide aggregates [Pt₂(μ-S)₂(PPh₃)₄ZnL]⁺, isolated as their BF₄^? salts. The complexes were characterized by NMR spectroscopy, ESI mass spectrometry, microelemental analysis, and an X-ray structure determination of the tosylamidoquinoline derivative [Pt₂(μ-S)₂(PPh₃)₄Zn(TAQ)]BF₄, which showed a distorted tetrahedral coordination geometry at zinc. Additional examples, containing picolinate, dithiocarbamate, or dithiophosphinate ligands were also synthesized and partly characterized in order to demonstrate a wider range of available derivatives.     

Comparative study of [RuClCp(HdmoPTA-κP)(PPh3)][CF3SO3] and the heterobimetallic complexes [RuClCp(PPh3)-μ-dmoPTA-1κP:2κ2N,N'-M(acac-κ2O,O')2] (M=Co, Ni, Zn; dmoPTA=3,7-dimethyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane)

The synthesis of novel heterobimetallic derivatives of general formula [RuClCp(PPh(3))-μ-dmoPTA-1κP:2κ(2)N,N'-M(acac-κ(2)O,O')(2)] (M = Ni (3), Zn (4); dmoPTA = 3,7-dimethyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane) is described. The preparations of the ruthenium-cobalt analogue (M = Co (2)) and the starting compound [RuClCp(HdmoPTA-κP)(PPh(3))](CF(3)SO(3)) have been revised and their yield improved. Similar to 2, the solid state structures of 3 and 4 show that the dmoPTA-P and the dmoPTA-N(CH(3)) atoms are involved in the coordination to the {RuCpCl(PPh(3))} and {M(acac)(2)} moieties, respectively. The size of the diffusing units is almost the same for the three binuclear complexes, indicating that they exhibit similar solution structures. The diamagnetic ruthenium-zinc derivative was fully characterized in solution at 193 K by NMR as two diastereomeric pairs of enantiomers (R-Ru, Δ-Zn; R-Ru, Λ-Zn; S-Ru, Δ-Zn; S-Ru, Λ-Zn). Finally, the electrochemical properties of the complexes have been investigated by cyclic voltammetry.     

Crystal structure of [Ph4As]2[Re7C(CO)21Au(PPh3)]. Comparison of H+ and Au(PPh3)+ coordination to [Re7C(CO)21]3−

The structure of [Ph₄As]₂[Re₇C(CO)₂₁Au(PPh₃)] has been determined by X-ray crystallography. The mixed-metal cluster anion adopts a 1,4- (i.e. trans-) bicapped octahedral geometry. Solution ¹³C NMR spectra reveal that this Au(PPh₃)⁺ adduct of [Re₇C(CO)₂₁]³⁻ maintains the (1,4)-bicapped structure in solution whereas the corresponding H⁺ adduct, [HRe₇C(CO)₂₁]²⁻, displays two isomers.