Synthese und Eigenschaften der heteronuklearen Metallatomcluster Re4(CO)12[μ3-GaRe(CO)5]4 und Re2(CO)3[μ-GaRe(CO)5]2

Synthesis and Properties of Heteronuclear Metal Atom Clusters Re₄(CO)₁₂[μ₃-GaRe(CO)₅]₄ and Re₂(CO)₈[μ-GaRe(CO)₅]₂ The title compounds were prepared by the reaction of gallium halides and dirhenium decacarbonyl. Crystals of the four-membered cluster Re₂(CO)₈[μ-GaRe(CO)₅]₂ gave at 300⁰C with aggregation of four Re atoms to an inner Re₄ tetrahedron the product Re₄(CO)₁₂(CO)[μ₃-GaRe(CO)₅]₄and with Ga₂I₃ shown by mass spectroscopic measurements the molecule ion Re₄(CO)₁₆+. In tetra-hydrofuran solution the cluster Re₄(CO)₁₂[μ₃-GaRe(CO)₅]₄ and the hydride Li[C₂H₅)₃BH] have formed the formyl complex Li₄{Re₄(CO)₁₂[μ₃ -GaRe(CO)₄(CHO)] ₄}, which was estimated by ¹H n. m. r. and i. r. spectroscopic data. Both synthesized gallium rhenium carbonyl clusters were characterized by i.r. spectroscopic measurements. The comparison of these results with those of the structurally known indium rhenium carbonyl clusters led to proposals of the molecule structure of the analogous gallium rhenium compounds.     

Rhenium(I) Tellurolate,Telluroether and Bidentate-Telluroether Complexes: Crystal Structures of Re(CO)3Br(PhTe(CH2)3TePh), PhTeRe(CO)5 Re2(μ-SePh)2(CO)8 and [(PhTeMe)Re(CO)5][BF4]

The monomeric rhenium(I) complex with bidentate telluroether ligand Re(CO)₃Br(PhTe(CH₂)₃TePh) (1) was accessible via reaction of the PhTe(CH₂)₃TePh with Re(CO)₅Br. This chelate complex crystallized in triclinic space group $ {\rm P}\bar 1 $ with a = 9.390(5) Å, b = 10.961(3) Å, c = 11.849(4) Å a = 63.30(3)°, β = 87.49(4)° γ = 69.31(4)°, V = 1009.5(7) ų Z = 2, R = 0.033, and R_w = 0.034. Reaction of Re(CO)₅Cl with NaTePh yielded the Re(I) specics PhTeRe(CO)₅ (2). This complex crystallized in triclinic space group $ {\rm P}\bar 1 $ with a = 7.085(1) Å, b = 9.203(1) Å, c = 11.341(1) Å, α = 107.24(1)°, β = 100.56(1)°, γ = 96.47(1)°, V = 683.2(2) ų, Z = 2, R = 0.027, R_w = 0.022. Reaction of PhTeRe(CO)₅ and (PhSe)₂ in THF at 65 °C yielded a product that was confirmed crystallographically to be the known species Re₂(μ-SePh)₂(CO)₈ (3), in which two phenylselenolate ligands bridge the two Re(I). Compound 3 crystallized in monoclinic space group P2₁/n with a = 7.210(2) Å, b = 18.862(6) Å, c = 9.083(3) Å, β = 107.48(3)° V = 1178.2(7) ų, Z = 2, R = 0.046, and R_w = 0.051. Methylation of PhTeRe(CO)₅ with [Me₃O][BF₄] afforded Re(I) product [(PhTeMe)Re(CO)₅][BF₄] (4). This monodentate telluroether species crystallized in monoclinic space group P2₁/n with a = 8.405(1) Å, b = 13.438(3) Å, c = 15.560(2) Å, β = 92.59(1)° V = 1755.5(5) ų, Z = 4, R = 0.035, and R_w = 0.035.     

Halogenverbrückte Heterometallatomcluster der drei Typen Re2(CO)4L2(μ-X)2(μ-Y) (L = (C6H5)3P; X = Br,I; Y = GaRe(CO)4ax-L), Re2(CO)6L2(μ-X)(μ-GaX2) (X = I) und Re3(CO)9L3(μ-X)3(μ-Y) (X = Cl)

Halogeno-Bridged Heteronuclear Metal Atom Clusters of the Three Types Re₂(CO)₄L₂(μ-X)₂(μ-Y) (L = (C₆H₅)₃P; X = Br, I; Y = GaRe(CO)₄ax-L), Re₂(CO)₆L₂(μ-X) (μ-GaX₂) (X = I), and Re₃(CO)₉L₃ (μ-X)₃(μ₃-Y) (X = Cl) The title compounds of the both types Re₂(CO)₄L(μ-X)₂(μ-Y) [L = (C₆H₅)₃P; X = Br, I; Y = GaRe(CO)₄ax-L] and Re₃(CO)₉L₃(μ-X)₃ (μ₃-Y) (X = Cl) were prepared by the reaction of GaX₃ (X = Cl, Br, I) and Re₂(CO)₈(ax-L)₂ in boiling mesitylene solution. The obtained substance Re₂(CO)₄L₂(μ-I)₂(μ-Y) and carbon monoxide gave the compound of the third type Re₂(CO)₆L₂(μ-I)(μ- GaI₂). The last-named single iodo-bridged dirhenium cluster could be therefore a precursor complex of the double iodo-bridged compound. The four diamagnetic substances were characterized by ³¹P n.m.r. spectroscopy and their molecular structures were acertained by X-ray measurements. The result of the single crystal X-ray analysis of Re₂(CO)₄L₂(μ-Br)₂ [μ-GaRe(CO)₄ax-L], a bridged coordination octahedron pair with a common face, and that of the edge-bridged pair Re₂(CO)₆L₂(μ-I)(μ-GaI₂) each possessing a Re? Re bond are especially treated in the present work.     

Ligand-promoted solvent-dependent ionization and conformational equilibria of Re(CO)3Br[CH2(S-tim)2] (tim = 1-methylthioimidazolyl). Crystal structures of Re(CO)3Br[CH2(S-tim)2] and {Re(CO)3(CH3CN)[CH2(S-tim)2]}(PF6)

The compounds Re(CO)3Br[CH2(S-tim)2] (1) and {Re(CO)3(CH3CN)[CH2(S-tim)2]}(PF6) (2), where tim is 1-methylthioimidazolyl, were prepared in high yields and characterized both in the solid state and in solution. The solid-state structures show that the ligand acts in a chelating binding mode where the eight-member chelate ring adopts twist-boat conformations in both compounds. A comparison of both solid-state IR data for CO stretching frequencies and the solution-phase voltammetric measurements for the Re(1+/2+) couples between 1, 2, and related N,N-chelates of the rhenium tricarbonyl moiety indicate that the CH2(S-tim)2 ligand is a stronger donor than even the ubiquitous dipyridyl ligands. A combination of NMR spectroscopic studies and voltammetric studies revealed that compound 1 undergoes spontaneous ionization to form {Re(CO)3(CH3CN)[CH2(S-tim)2]+}(Br-) in acetonitrile. Ionization does not occur in solvents such as CH2Cl2 or acetone that are less polar and Lewis basic (less coordinating). The equilibrium constant at 293 K for the ionization of 1 in CH3CN is 4.3 x 10(-3). The eight-member chelate rings in each 1 and 2 were found to be conformationally flexible in all solvents, and boat-chair conformers could be identified. Variable-temperature NMR spectroscopic studies were used to elucidate the various kinetic and thermodynamic parameters associated with the energetically accessible twist-boat to twist-boat and twist-boat to boat-chair interconversions.     

Darstellung und Strukturen von (Et4N)2[Re(CO)3(NCS)3] und (Et4N)[Re(CO)2Br4]

Syntheses and Structures of (Et₄N)₂[Re(CO)₃(NCS)₃] and (Et₄N)[Re(CO)₂Br₄] Rhenium(I) and rhenium(III) carbonyl complexes can easily be prepared by ligand exchange reactions starting from (Et₄N)₂[Re(CO)₃Br₃]. Using nonoxidizing reagents the facial Re^I(CO)₃ unit remains and only the bromo ligands are exchanged. Following this procedure, (Et₄N)₂[Re(CO)₃(NCS)₃] can be obtained in high yield and purity using trimethylsilylisothiocyanate. The compound crystallizes in the monoclinic space group P2₁/n, a = 18.442(5), b = 17.724(3), c = 18.668(5) Å, β = 92.54(1)°, Z = 8. The NCS^? ligands are coordinated via nitrogen. The reaction of [Re(CO)₃Br₃]^2? with Br₂ yields the rhenium(III) anion [Re(CO)₂Br₄]^?. The tetraethylammonium salt of this complex crystallizes in the noncentrosymmetric, orthorhombic space group Cmc2₁, a = 8.311(1), b = 25.480(6), c = 8.624(1) Å, Z = 4. The carbonyl ligands are positioned in a cis arrangement. Their strong trans influence causes a lengthening of the Re? Br bond distances by at least 0.05 Å.     

Selektive Darstellung zweifach diorganophosphido-verbrückter Metallatetrahedrane [Re2(MPR3)2(μ-PR2)2(CO)6] mit Re2M2-Metallgerüst (M = Au,Ag)

Selective Preparation of Twofold Diorganophosphido-bridged Metallatetrahedranes [Re₂(MPR₃)₂(μ-PR₂)₂(CO)₆] with Re₂M₂ Metal Core (M = Au, Ag) The reaction of the in situ prepared salt Li[Re₂(AuPR)(μ-PR₂)(CO)₇Cl] (R = R′ = Cy ( 1 a ), R = Cy, R′ = Ph ( 1 b ), R = Ph, R′ = Cy ( 1 c ), R = Ph, R′ = Et ( 1 d ), R = Ph, R′ = Ph ( 1 e )) with one equivalent HPR in methanolic solution at room temperature yields the neutral cluster complexes [Re₂(AuPR)(μ-PR₂)(CO)₇(ax-HPR) (R = R′ = R″ = Cy ( 2 a ), Ph ( 2 b ), R = R′ = Cy, R″ = Et ( 2 c ), R = Cy, R′ = R″ = Ph ( 2 d ), R = Cy, R′ = Ph, R″ = Et ( 2 e ), R = R″ = Ph, R′ = Et ( 2 f ), R = Ph, R′ = Cy, R″ = Et (2 g)). Photochemically induced these complexes react in the presence of the organic base DBU in THF solution to give the doubly phosphido bridged anions Li[Re₂(AuPR)(μ-PR₂)(μ-PR)(CO)₆], which were characterized as salts PPh₄[Re₂(AuPR)(μ-PR₂)(μ-PR)(CO)₆] (R = R′ = R″ = Ph ( 3 a ), R = R′ = Ph, R″ = Cy ( 3 b ), R = Ph, R′ = Cy, R″ = Et ( 3 c ), R = R″ = Ph, R′ = Et ( 3 d )). These precursor complexes 3 then react with one equivalent of ClMPR (M = Au, Ag) to doubly phosphido bridged metallatetrahedranes [Re₂(MPR₃)₂(μ-PR₂)(μ-PR)(CO)₆] (M = Au, R = R′ = R″ = Ph ( 4 a ), M = Au, R′ = Et, R = R″ = Ph ( 4 b ), M = Au, R = R′ = Ph, R″ = Cy ( 4 c ), M = Au, R = Cy, R′ = Ph, R″ = Et ( 4 d ), M = Ag, R = R′ = R″ = Ph ( 4 e )). All isolated cluster complexes were characterized and identified by the following analytical methods: NMR- (¹H, ³¹P) and ν(CO) IR-spectroscopy and, additionally, complexes 2 b , 4 a and 4 e by X-ray structure analysis.     

Chemiluminescence effects in the reactions of Mn2(CO)10, Re2(CO)10, and Re2(CO)8Phen with XeF2 in solution

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2184–2185, September, 1990.     

[Re5(μ-H)4(CO)20]− and [Re5(μ-H)5(CO)20], Two Isolobal Analogues of Cyclopentane

The first five-membered rings of metal atoms connected by M–M or M-H-M bonds only have been obtained by a Re₂+Re₃ condensation in which a polyhydride acts as a bridging bidentate ligand toward a coordinatively unsaturated fragment (see scheme below). In spite of the octahedral coordination of the Re centers, the Re₅ rings display conformations (twisted and envelope) comparable with those observed for organic five-membered rings of tetrahedral carbon atoms.     

Mechanism of (&mgr;-H)(&mgr;-alkenyl)Re(2)(CO)(8) Formation in 350 nm Flash Irradiations of Re(2)(CO)(10)

The mechanism of (&mgr;-H)(&mgr;-alkenyl)Re(2)(CO)(8) formation upon UV irradiations of Re(2)(CO)(10) in presence of olefin (styrene, trans-stilbene, 4-methyl-1-cyclohexane, and ethylene) was investigated by laser flash photolyses. Such photoproducts result from reactions of the olefin with eq-Re(2)(CO)(9). No reactions of Re(CO)(5) leading to hydride alkenyl products were observed. Dependences of the reaction rate on olefin concentration and solvent revealed an additional intermediate formed after the addition of the olefin to eq-Re(2)(CO)(9) and before the appearance of the &mgr;-hydrido-&mgr;-alkenyl products.     

Exploring the intermediates of photochemical CO2 reduction: reaction of Re(dmb)(CO)3 COOH with CO2

We have investigated the reaction of Re(dmb)(CO)(3)COOH with CO(2) using density functional theory, and propose a mechanism for the production of CO. This mechanism supports the role of Re(dmb)(CO)(3)COOH as a key intermediate in the formation of CO. Our new experimental work supports the proposed scheme.     

Synthesis and Crystal Structure of (CO)5ReSnMe2Re(CO)5

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Heterometallatom-Koordinationsverbindungen Re2(μ-PPh2)2[mer-(CO)3]2-trans-[InX2(H2O)]2 und neue halogenhaltige drei- und vierkernige Rheniumcluster aus Reaktionen zwischen Re2[μ-PPh2)2(CO)8] und InX3 (X = Cl,Br, I)

Heterometallic Coordination Compounds Re₂(μ-PPh₂)₂[mer-(CO)₃]₂-trans-[InX₂(H₂O)]₂ and New Halogene Containing Three- and Four-Nuclear Rhenium Clusters from Reactions between Re₂(μ-PPh₂)₂(CO)₈ and InX₃ (X = Cl, Br, I) In sealed glass tubes equimolar amounts of Re₂(μ-PPh₂)₂(CO)₈ and InX₃ (X = Cl, Br, I) were reacted in the presence of xylene at 220°C to two types of products. The first type comprised the heterometallic coordination compounds Re₂(μ-PPh₂)₂(CO)₆[InX₂(H₂O)]₂ (X = Cl, Br, I) (yield 60%), and the second halogene containing rhenium complexes Re₃(μ₃-H)(μ₃-X)(μ-PPh₂)₃(CO)₆ (unsaturated three-membered metal ring with 46 VE) and Re₄(μ-H)(μ-X)(μ-PPh₂)₄(μ₄-PPh)(CO)₈ and additionally those substances as cis-IRe(CO)₄(PPh₂H), Re₂(μ-PPh₂)(μ-X)(CO)₈ (X = Cl, Br), Re₂(μ-I)₂[μ-(PPh₂)₂O](CO)₆ and Re₄(μ-Cl)₂(μ-PPh₂)₄(μ₄-PPh)(CO)₈ (four-membered metal ring with 66 VE with three Re? Re bonds) which have been observed in one or two of the three reaction systems. A proposal of the reaction course is discussed. The single X-ray analysis of Re₂(μ-PPh₂)₂[mer(CO)₃]₂-trans[InI₂(H₂O)]₂ · 2 Me₂CO shows for the two fold phosphido bridged dirhenium molecular fragment with 34 VE a Re? Re bond of 294.6(1) pm. From two possible transpositions of both In? Re bond vectors, the one found advantageously has sterical reasons. The average In? Re single bond length is 271.1(1) pm. The corresponding determination of the unsaturated three-membered ring compound Re₃(μ₃-H) (μ₃-Cl)(μ-PPh₂)₃(CO)₆ showed three Re? Re bond lenghts of comparable size, of which the mean value of 281.9(1) pm was significantly shortened by π electron delocalization effect compared to that of a saturated phosphido bridged three-membered rhenium ring compound. As it was recognized by further comparison, the structural data of the common molecular fragments in the three examined three-membered rhenium ring clusters (X = Cl, Br, I) are not dependent on the different kind of halogeno ligand atoms. Finally, the crystal structure determination of the substance Re₄(μ-H)(μ-Br)(μ-PPh₂)₄(μ₄-PPh)(CO)₈ shows the presence of square-pyramidal Re₄(μ₄-P) atomic arrangement, of which the planar basic plane has a sequence of up- and downwards orientated four diphenylphosphido bridging groups. The four measured Re? Re single bond lengths (mean value 302.7(3) pm change with the different kind of bridging atoms. The structural features observed are compared with those of a corresponding iodine derivative.     

Diazenide and hydrazide(2-) derivatives of the [Re(CO)3]+ core

Reaction of [ReBr3(CO)3]2- with aryldiazonium salts gives the Re(iii) diazenide complexes [ReBr2(NNC6H4R-4)(CO)2]-. The attachment of a PhNHCS tethering group to pyridyl hydrazine generates a HYNIC related proligand which gives a stable chelated pyridyliumthiocarbazide(2-) derivative of the [Re(I)(CO)3]+ core.