New polynuclear molecular ferromagnetic complex {Co3((η2-NH2)2C6H2Me2)2(μ-OOCCMe3)2(η1-OOCCMe3)2(η2-OOCCMe3)2(HOOCCMe3)2}{Co((η2-NH2)2C6H2Me2)2(η1-OOCCMe3)2}

Russian Chemical Bulletin -     

Comparison of the Bonding of Benzene and C60 to a Metal Cluster: Ru3(CO)9(μ3-η2,η 2,η2-C6H6) and Ru3(CO)9(μ3-η2,η2,η2-C60)

The electron distributions and bonding in Ru₃(CO)₉( ³- ², ², ²-C₆H₆) and Ru₃(CO)₉( ³- ², ², ²-C₆₀) are examined via electronic structure calculations in order to compare the nature of ligation of benzene and buckminsterfullerene to the common Ru₃(CO)₉ inorganic cluster. A fragment orbital approach, which is aided by the relatively high symmetry that these molecules possess, reveals important features of the electronic structures of these two systems. Reported crystal structures show that both benzene and C₆₀ are geometrically distorted when bound to the metal cluster fragment, and our ab initio calculations indicate that the energies of these distortions are similar. The experimental Ru–C_fullerene bond lengths are shorter than the corresponding Ru–C_benzene distances and the Ru–Ru bond lengths are longer in the fullerene-bound cluster than for the benzene-ligated cluster. Also, the carbonyl stretching frequencies are slightly higher for Ru₃(CO)₉( ³- ², ², ²-C₆₀) than for Ru₃(CO)₉( ³- ², ², ²-C₆H₆). As a whole, these observations suggest that electron density is being pulled away from the metal centers and CO ligands to form stronger Ru–C_fullerene than Ru–C_benzene bonds. Fenske-Hall molecular orbital calculations show that an important interaction is donation of electron density in the metal–metal bonds to empty orbitals of C₆₀ and C₆H₆. Bonds to the metal cluster that result from this interaction are the second highest occupied orbitals of both systems. A larger amount of density is donated to C₆₀ than to C₆H₆, thus accounting for the longer metal–metal bonds in the fullerene-bound cluster. The principal metal–arene bonding modes are the same in both systems, but the more band-like electronic structure of the fullerene (i.e., the greater number density of donor and acceptor orbitals in a given energy region) as compared to C₆H₆ permits a greater degree of electron flow and stronger bonding between the Ru₃(CO)₉ and C₆₀ fragments. Of significance to the reduction chemistry of M₃(CO)₉( ³- ², ², ²-C₆₀) molecules, the HOMO is largely localized on the metal–carbonyl fragment and the LUMO is largely localized on the C₆₀ portion of the molecule. The localized C₆₀ character of the LUMO is consistent with the similarity of the first two reductions of this class of molecules to the first two reductions of free C₆₀. The set of orbitals above the LUMO shows partial delocalization (in an antibonding sense) to the metal fragment, thus accounting for the relative ease of the third reduction of this class of molecules compared to the third reduction of free C₆₀.     

(η6-Anisole) (η2-benzene) dicarbonylchromium(0): an intermediate in the photochemical carbonyl substitution of (η6-anisole)tricarbonylchromium(0) in benzene

The photochemical carbonyl substitution of (η⁶-anisole)Cr(CO)₃ has been investigated by laser flash photolysis. Both transient spectra and second-order rate constants for the reactions of transients with nucleophiles are found to be extremely variable depending upon solvents used. The coordination of benzene to the transient in cyclohexane forms the transient in benzene, indicating two discrete chemical species: (η⁶-anisole)Cr(CO)₂ and (η⁶-anisole)Cr(CO)₂(η²-benzene). The latter type of transient was observed also for fluorobenzene and mesitylene, leading to the assignment of a weak band in the visible region as η²-arene → Cr charge transfer. The existence of (η⁶-arene)Cr(CO)₂(η²-arene′) may throw light on what have been described as solvent effects in organometallic reactions.     

Synthesis,molecular structure and spectroscopic characterization of MO(CO)2I2 (η2-dppm)(η1-dppm)

A new, high-yield method has been developed for the preparation of MO(CO)₂I₂(η²-dppm)(η¹-dppm). The title compound was prepared by the reaction of [Et₄N][Mo(CO)₄I₃] with dppm in benzene in 95% yield. It has been characterized by a single-crystal X-ray study. The crystallographic data are as follows: monoclinic, space group P2₁/n, a = 19.023(4) Å, b = 14.439(3) Å, c = 20.141(5) Å, β = 100.45(2)°, V = 5440(2) ų Z = 4. The geometry around the central metal atom could be considered as either a distortion from a capped octahedron with a carbonyl in a capping position or from a trigonal prism with the iodine capping a rectangular face. The solution behavior of Mo(CO)₂I₂(dppm)₂ was examined with ³¹P NMR, which showed it to be fluxional.     

Reaction of alkyne cluster Os3(μ-CO)(CO)9(μ3-η1:η1:η2-Me3SiC2Me) with HC≡CCOOMe. Molecular and crystal structures of Os3(CO)9{μ3-η1:η1:η2:η2-C(SiMe3)C(Me)C(COOMe)CH× and Os3(CO)8{μ3-η1:η1:η4:η1-C(SiMe3)C(Me)C(H)C(COOMe)CH× complexes

Reaction of the cluster Os₃(μ-CO)(CO)₉(μ₃-η¹:η¹:η²-Me₃SiC₂Me) with HC≡CCOOMe in benzene at 70 °C results in Os₃(CO)₉{μ₃-η¹:η¹:η²:η²-C(SiMe₃)C(Me)C(COOMe)CH× (5), Os₃(CO)₉{μ₃-η¹:η¹:η²:η²-C(SiMe₃)C(Me)C(H)C(COOMe)CH× (6), Os₃(CO)₉{μ-η¹:η¹:η⁴-C(SiMe₃)C(Me)C(H)C(COOMe)CH× (7), and Os₃(CO)_δ{μ₃-η¹:η¹:η⁴:η¹-C(SiMe₃)C(Me)C(H)C(COOMe)× complexes (8), containing an osmacyclopentadiene moiety. Complexes5–8 were characterized by¹H NMR and IR spectroscopy. The structure of clusters5 and8 was confirmed by X-ray analysis. Complex7 is formed from cluster5 as a result of a new intramolecular rearrangement and complex8 is obtained by decarbonylation of compound6. Complex8 adds PPh₃ to give Os₃(CO)_δ(PPh₃){μ-η¹:η¹:η⁴-C(SiMe₃)C(Me)C(H)C(COOMe)×.     

Phosphine-centred resolution of (η4-diene)Fe(CO)3 complexes: (η4-tropone)Fe(CO)2L and (η4-isoprene)Fe(CO)2L [L = (+)-(neomenthyl)PPh2]

(η⁴-Tropone)Fe(CO)₃ and (η⁴-isoprene)Fe(CO)₃ form separable diastereoisomers on substitution of CO by (+)-(neomenthyl)PPh₂. In the tropone complex, diastereoisomer interconversion occurs by a 1,3-metal shift. The absolute configuration of the isoprene complex has been determined crystallographically.     

Organodiphosphines in cis-Pt(η2-P2L)(η2-S2L) derivatives – structural aspects

Abstract

In this review structural parameters of forty complexes with an inner coordination sphere of Pt(η²-P₂L)(η²-S₂L) are analyzed and classified These complexes crystallize in three crystal systems: orthorhombic (four examples), triclinic (six examples) and monoclinic (thirty examples). The organodiphosphines create four- (PCP), five- (PC₂P), six- (PC₃P) and seven- (PC₄P) membered metallocyclic rings with mean P-Pt-P bite angle values of 72.5° (PCP) < 85.3° (PC₂P) < 93.0° (PC₃P) < 97.4° (PC₄P). The dithiolates create four- (SCS), five- (SC₂S), six- (SC₃S; SCSCS; SPNPS; SPCPS) and seven- (SC₄S) membered metallocyclic rings with mean S-Pt-S bite angle values of 74.5° (SCS) < 85.8° (SCSCS) < 87.0° (SPNPS) < 89.0° (SC₂S) < 92.3° (SC₄S) < 93.5° (SC₃S) < 97.5° (SPCPS). The mean Pt-P and Pt-S bond distances are 2.257 and 2.328?Å, respectively. The data are compared with those found in complexes with inner coordination spheres of Pt(PL)₂(SL)₂, Pt(PL)₂(η²-S₂L) and Pt(η²-P₂L)(SL)₂.     

Crystal and molecular structure of (μ-η2,η3-propargyl)- bis(cyclopentadienyl)tetracarbonyldimolybdenum tetrafluoroborate and (μ-η2,η3-1,1-dimethylpropargyl)- bis(cyclopentadienyl)tetracarbonyldimolybdenum tetrafluoroborate

An X-ray study of [(μ-η²,η³-HCCCH₂)Cp₂Mo₂(CO)₄]⁺(BF₄⁻) (1) and [(μ-η²,η³-HCCCMe₂)Cp₂Mo₂(CO)₄]⁺(BF₄⁻) (2) reveals their structures to be similar to the structure of neutral compounds of the series (μ-η²,η²-RCCR)Cp₂Mo₂(CO)₄, the difference between 1 and 2 being mainly due to the markedly different MoC⁺ bond lengths, which accounts for different stability and fluxional behavior of these compounds in solution.     

Syntheses and Anti-inflammatory Action of (η-C_5H_5)_2Ti(Cin)_2 and (η-C_5H_5)_2Ti(Tzea)_2

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Co(η(5) -P(5) ){η(2) -P(2) H(mes)}](2-) : A Phospha-Organometallic Complex Obtained by the Transition-Metal-Mediated Activation of the Heptaphosphide Trianion

A carbon copy: The chemical activation of the heptaphosphide trianion with [Co(PEt(2) Ph)(2) (mes)(2) ] (see picture; 1) yields the novel phospha-organometallic complex [Co(η(5) -P(5) ){η(2) -P(2) H(mes)}](2-) (2). The reaction product maintains the nuclearity of the parent cluster, but extensive cage fragmentation takes place to yield a diamagnetic "inorganometallic" cobalt complex.     

OMS, OM(η2-SO), and OM(η2-SO)(η2-SO2) molecules (M = Ti, Zr, Hf): infrared spectra and density functional calculations

Infrared spectra of the matrix isolated OMS, OM(η(2)-SO), and OM(η(2)-SO)(η(2)-SO(2)) (M = Ti, Zr, Hf) molecules were observed following laser-ablated metal atom reactions with SO(2) during condensation in solid argon and neon. The assignments for the major vibrational modes were confirmed by appropriate S(18)O(2) and (34)SO(2) isotopic shifts, and density functional vibrational frequency calculations (B3LYP and BPW91). Bonding in the initial OM(η(2)-SO) reaction products and in the OM(η(2)-SO)(η(2)-SO(2)) adduct molecules with unusual chiral structures is discussed.     

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.     

Molecular structure of ansa-compound (η5-C5H4)CMe2(η5-C9H6)TiCl2

The structure of a new ansa compound, (⁵-C₅H₄)CMe₂(⁵-C₉H₆)TiCl₂ (1), was studied by X-ray analysis:a = 15.00(1),b =15.500(5),c = 13.032(4) Å, = 92.66°(4),V = 3025.1(1) ų, space groupP2₁/.,R = 0.038. The distorted tetrahedral coordination sphere of the Ti atom is formed by two Cl atoms and two -ligands. It was proposed that the angle () between theC-M direction and the line normal to M-Cp can be considered as one of the geometric parameters characteristic of the structure-properties correlation.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 305–308, February, 1995.     

Reactions of (η6-diphenylacetylene) chromiumtricarbonyl complexes with polynuclear carbonyls I. Synthesis of Cr(CO)3(η6-diphenylacetylene) complex and its reaction with Co2(CO)8. Crystal and molecular structure of Cr(CO)3(η6:η2-diphenylacetylene)Co2(CO)6

The reaction of Cr(CO)₃(NH₃)₃ with diphenylacetylene affords as a main product the complex with Cr(CO)₃ moiety bound to a phenyl ring of diphenylacetylene; Cr(CO)₃(η⁶-PhC₂Ph) (I). Complex I readily reacts with Co₂(CO)₈ yielding the mixed metal complex Cr(CO)₃(η⁶:η²-PhC₂Ph)Co₂(CO)₆ (II). The reaction proceeds with retention of the Cr(CO)₃ (η⁶-arene) structural unit, the Co₂(CO)₆ fragment being bound to the triple bond of diphenylacetylene in μ₂,η²-mode. The structure of II was determined by single crystal X-ray analysis. The complex crystallizes in space group P2₁/c with unit cell parameters a 8.666(3) Å, b 18.046(3) Å, c 15.155(6) Å. β 97.57(3)°, V 2349(2) ų, Z = 4, D_x = 1.70 g/cm³. The structure was solved by direct methods and refined by full-matrix least-squares technique to R and R_w values of 0.032 and 0.034, respectively, for 3655 observed reflections. The data obtained show that two structural units in II, Cr(CO)₃(η⁶-Ph-) and Co₂(CO)₆(μ₂,η²-CC), are distorted due to steric repulsion between these metal carbonyl moieties. The Cr(CO)₃ fragment is shifted from the centre of the phenyl ring and slightly tilted with respect to the phenyl ring plane. The Co₂C₂ tetrahedron in the Co₂(CO)₆(μ₂,η²-CC) moiety is distorted in such a way that two of the four Co_iC_j bonds are elongated.     

Bis(indenyl)titanacyclopentan und bis(indenyl)(η2-ethylen)titan

Attempts to prepare (di-η⁵-indenyl)(η²-ethylene)methyltitamum (A) from (ind)₂TiCl, MeMgCl and ethylene led to the disproportionation products bis(η⁵-indenyl)titanacyclopentane (5) and bis(η⁵-indenyl)dimethyltitanium (4) instead of to A. 5 dissociates reversibly upon heating from −80 to −20°C giving (di-η⁵-indenyl)(η²-ethylene)titanium (6) and ethylene.     

Triphospha-Ferrocenes as Ligands. Crystal Structures of [Fe(η5-C5Me5)(η5-C2 TBu2P3)M(CO)5)], (M= Cr,MO, W) and the Novel ruthenium and Nickel Complexes [Fe(η5-C5Me5) (η5-C2 TBu2P3)Ru3(CO)9] and [Fe(η5-C5Me5)(η5-C2 tBu2P3)Ni(Co)2]2

Abstract

Syntheses and structures of penta- and hexaphosphorus analogues of ferrocene have been described recently¹. Unlike their simple ferrocene analogues, these complexes have further ligating potential towards other transition metal centres by virtue of the availability of the ring phosphorus lone-pair electrons that are not involved in the η⁵-coordination. We now describe the first examples of coordination compounds of the triphospha-ferrocene [Fe(η⁵-C₅Me₅) (η⁵-C₂ ^tBu₂P₃]. In the ruthenium complex [Fe(η⁵-C₅Me₅)(η⁵-C₂ ^tBu₂P₃) Ru₃(CO)₉] ² two adjacent phosphorus atoms of the η⁵-C₂ ^tBu₂P₃ ring are interlinked by a ruthenium carbonyl cluster in which all three ruthenium atoms interact with the phosphorus atoms. The tetrametallic nickel complex [Fe(η⁵-C₅Me₅)(η⁵-C₂ ^tBu₂P₃)Ni(CO)₂]₂ ³ represents the first example of intermolecular interlinkage of two phospha-ferrocene systems by two metal centres.     

过渡金属的分子氢(η~2-H_2)络合物

<正> 金属对分子H_2的活化反应,在应用科学及理论科学中均为重要的化学反应。H—H键是一强健(键能为431240.4J/mol)。因此H_2分子对不饱和物及其它化合物的加成反应,必须通过金属中心(M)的催化活化,形成碱性中间物M,即金属一分子H_2络合物(以下简称为分子H_2络合物),随后H—H键断裂形成金属氢化物MH。这一过程在催化加氢反应中起着重要作用。它可按两种方式进行:     

Synthesis and molecular structure of (η-pentamethyl-cyclopentadienyl) (η-cyclopentadienyl) hexacarbonyl molybdenum tungsten

The metathesis reaction of Cp*(CO)₃MoBr and NaW(CO)₃Cp produced Cp*(CO)₃Mo-W(CO)₃Cp (1), featuring an unsupported Mo-W bond. Exposure of solutions of 1 to light leads to the quantitative formation of the corresponding homometallic dimers. In the solid state, the title complex exhibits an anti-arrangement of the η⁵-cyclopentadienyl and the η⁵-pentamethyl-cyclopentadienyl ligands and six terminal carbonyls. Comparison to corresponding complexes of molybdenum and tungsten reveals that the Mo-W distance is dictated by the presence of a Cp and a Cp* ligand. This is the first time that an unsupported Mo-W single bond distance is reported.     

Synthesis and structures of the η5-C5H5Cl(CO)2W-η1,η5-(PPh2)C5H4(CO)2Fe-η1,η5-C5H4Mn(CO)3 and MeSi[C5H4(CO)2Fe-η1,η5-C5H4Mn(CO)2PPh3]3 complexes

The metallation of the η⁵-C₅H₅(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃ complex with BuⁿLi (THF, ?78 °C) followed by the treatment of the lithium derivative with Ph₂PCl afforded the η⁵-Ph₂PC₅H₄(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃ complex. The reaction of the latter with η⁵-C₅H₅(CO)₃WCl in the presence of Me₃NO produced the trinuclear complex η⁵-C₅H₅Cl(CO)₂W-η¹,η⁵-(Ph₂P)C₅H₄(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃. The structure of the latter complex was established by IR, UV, and 1H and ³¹P NMR spectroscopy and X-ray diffraction. The reaction of MeSiCl₃ with three equivalents of LiC₅H₄(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₂PPh₃ gave the hexanuclear complex MeSi[C₅H₄(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₂PPh₃]₃.