Antiferromagnetic complexes involving metalmetal bonds : I. Synthesis and molecular structure of an antiferromagnetic dimer with a CrCr bond

The binuclear complex (C₅H₅)₂Cr₂(S)(SCMe₃)₂ was prepared by refluxing a solution of chromocene and t-butylmercaptane in heptane. The structure of the product was determined by single crystal X-ray diffraction. The chronium atoms are linked by a sulphide bridge (SCr 2.24 Å;, <CrSCr 74.1° and two SCMe₃ bridges (CrS 2.38 Å;, <CrSCr 68.3–69.3°). The two cyclopentadienyl ligands (CC 1.41 Å;, CrC 2.23 Å;) are in apical positions, their ring planes being parallel to each other. The complex is an antiferromagnet (?2J cm^?1) despite the small CrSCr angles and short chromiumchromium distance (2.689 Å;) indicative of strong CrCr bonding.     

Synthesis and molecular structure of niobocene(tricarbonyl)(π-cyclopentadienyl)molybdenum with metalmetal bond and unusual coordination of carbonyl groups

(C₅H₅)₂NbBH₄ reacts with C₅H₅M(CO)₃Me in toluene solution in the presence of Et₃N to give binuclear complexes (C₅H₅)₂NbM(CO)₃C₅H₅ where M is Mo or W (IV and V, respectively). The structure of IV has been studied by X-ray diffraction (the crystals are orthorhombic, a 12.748(5), b 16.745(6), c 14.314 $\text{A/ac>}\text{?}$;; Z = 8, space group of Pbca, automatic difractometer Syntex P2_I, λ(Mo-K_α, 1382 reflections, R = 0.056, R_w = 0.058). Molecule IV contains a wedge-like sandwich (π-C₅H₅)₂Nb (NbC 2.37–2.48, CC (av) 1.42 $\text{A/ac>}\text{?}$;, angle between ring planes 49°) linked with the (π-C₅H₅)Mo(CO) fragment by a direct NbMo bond (3.073 $\text{A/ac>}\text{?}$;) and two bridging CO groups, one nonsymmetrically bonded through the carbon atom only (CO 1.17, NbC 2.53, MoC 2.02 $\text{A/ac>}\text{?}$;) and the other σ-bonded to Mo (MoC 1.944 $\text{A/ac>}\text{?}$;) and π-bonded to Nb (CO 1.22, NbC 2.22, NbO 2.26 $\text{A/ac>}\text{?}$;). Three types of carbonyl groups present in IV give rise to strong IR bands at 1870, 1700 and 1560 cm^?1 assigned to the terminal, μ-bridging and σ, π-bridging CO groups respectively. Complex IV has a similar structure. The electronic structure of IV and its dissociation across the NbMo bond are discussed.     

Characteristic structural features of cyclopentadienyl derivatives of post-transition metals : II. Synthesis and structure of tris(triphenylphosphinegold)tetraphenylcyclopentadiene tetrafluoroborate

The trinuclear cationic complex [Ph₄C₅(AuPPh₃)₃⁺[BF₄]^- (I) obtained by interaction of C₅HPh₄AuPPh₃ or Ph₄C₅(AuPPh₃)₂ with [AuPPh₃⁺[BF₄]^- in THF was studied by X-ray diffraction. In the presence of benzene, triclinic crystals of the solvate [Ph₄C₅(AuPPh₃)₃]⁺[BF₄]^-· 2 C₆H₆ are formed, a = 12.845(6), b = 16.042(8), c = 22.642(11) Å, α = 86.62(4), β = 77.51(4), γ = 76.05(4)°, space group P$\text{1}$, Z = 2, 9494 reflections with I > 2σ (λ(Mo-K_α), θ/2θ scan, 2θ < 46°), with absorption correction R = 0.054. The complex represents a diaurated cation of tetraphenylcyclopentadienyl(triphenylphosphine)gold, containing a triangular Au₂C fragment (AuAu 2.820(1) Å) which is bonded to the third Au atom (AuAu 3.021(1) Å), coordinated to the cyclopentadienyl ligand by a bond intermediate between η¹(σ) and η³ (AuC 2.21(2), 2.60(2) and 2.71(2) Å).     

Heterobimetallic Complexes: Substitution Effects in the [Tetracarbonylrhodiumbis{μ‐(diphenylphosphino)}{μ‐(η:η2‐(4‐diphenylphosphino‐κP)‐2‐methyl‐oxobutyl)}molybdenum](Mo‐Rh) System

Syntheses of the array of heterobimetallic complexes [(OC)₃M(μ‐PPh₂)₂(μ‐O‐C(CHMe(CH₂)₂PPh₂)RhL], M = Cr, Mo, W, L = ^tBuNC, are described, extending the previous study of the counterpart array for L = CO. A single crystal X‐ray structure determination is reported for the M = Mo adduct, enabling comparison with its previously reported L = CO counterpart, for which an improved redetermination is also reported. In the present complex the ^tBuNC ligand is found to be much more weakly bound (Rh‐C 2.026(5) Å) than the carbonyl group it displaces (Rh‐C 1.945(2) Å) with concomitant minor impact on the remainder of the rhodium ambience.     

Direct synthesis from MoCl3(THF)3 of a complex containing the [Mo3S4]4+ core

By reaction of MoCl₃(THF)₃ with NaSH in tetrahydrofuran, followed by addition of Me₂PCH₂CH₂PMe₂(dmpe), then chromatography on silica-gel, and finally addition of NH₄PF₆, the compound [Mo₃S₄Cl₃(dmpe)₃]PF₆·CH₃OH was prepared in moderate yield. X-ray crystallography showed the presence of a chiral cation based on a Mo₃S₄ core with chelating dmpe units arranged like the blades of a ship's screw. The three Cl atoms fill the remaining octahedral sites on each metal atom. The compound crystallizes in space group R3c with (hexagonal) cell dimensions of a = 15.310(7) Å, c = 30.640(3) Å and Z = 6. The [Mo₃S₄Cl₃(dmpe)₃]⁺ ion and the PF₆⁻ ion each have crystallographic C₃ symmetry. The principal distances and theirs esds are: MoMo, 2.766(4) Å; Mo(μ₃-S), 2.360(9) Å; Mo(μ₂-S), 2.290(7) Å, 2.336(7) Å; MoP, 2.534(8) Å, 2.605(8) Å; MoCl, 2.473(7) Å; PF, 1.56(2) Å, 1.64(3) Å. The correct enantiomer was obtained by refining both to convergence, which give R = 0.059 and R = 0.064.     

A large-angle X-ray scattering study of two amorphous inorganic polymers,Ru(SPh)3 and Mo(SPh)3

The two inorganic polymers Ru(SPh)₃ and Mo(SPh)₃ were examined by large-angle X-ray scattering, showing in both cases chains of face-sharing octahedra with alternating metal-metal distances (RuRu: 3.25 and 2.65 Å; MoMo: 3.30 and 2.70 Å).     

Highly reduced organometallics: XII. The reaction of a carbonyltungstate anion with triphenyltin chloride resulting in a phenyltin bond cleavage. X-ray structural characterization of the novel salt: [Me4N][(Ph3Sn)2{(Ph2Sn)2O-i-Pr}W(CO)3]

The reaction of a highly reduced tricarbonyltungstate species with triphenyltin chloride results in an unprecedented phenyl-tin cleavage and the formation of an unusual substituted carbonyl anion. The X-ray structure of [Me₄N][(Ph₃Sn)₂-{(Ph₂Sn)₂O-i-Pr}W(CO)₃] shows the presence of seven coordinate tungsten bound to three terminal carbonyl groups, two triphenyltin units and a previously unknown isopropoxo-bis(diphenyltin) bidentate ligand. The seven ligating atoms are disposed in an approximate 4 : 3 piano stool arrangement about the central tungsten atom. Crystal data: Space group P2₁/c, a 22.580(10), b 14.162(4), c 23.070(10) Å, β 114.21(4)°, Z = 4, V 6728(1) ų, ?(calc) 1.626 g cm^?3.     

Fulvene—platinum complexes: x-ray crystal structure of [Pt(η2-C5H4CPh2)(PPh3)2]

Bis(cycloocta-1,5-diene)platinum reacts with 2,3,4,5-tetraphenylfulvene to afford the complex [Pt(η²-CH₂C₅Ph₄)(cod)] (cod  C₈H₁₂) in which the metal atom is coordinated to the exo-cyclic double bond of the fulvene. Related compounds [Pt(η²-CH₂C₅Ph₄L₂] (L  PPh₃, PMePh₂, PMe₂Ph, AsPh₃ or CNBu^t have also been prepared and characterised. Reaction of the complexes [Pt(C₂H₄)₂(L)] (L  P(cyclo-C₆H₁₁)₃, PPh₃ or AsPh₃) with 2,3,4,5-tetraphenylfulvene yields the compounds [Pt(C₂H₄)(η²-CH₂C₅PH₄)(L)]. NMR data for the new species are reported and discussed. 6,6-Diphenylfulvene reacts with [Pt(cod)₂] and PPh₃ ($\text{1}\text{2}$ mol ratio) to give the complex [Pt(η²-C₅H₄CPh₂)-(PPh₃)₂] in which the metal atom is bonded to carbon atoms C(2) and C(3) of the fulvene ring. This was established by an X-ray diffraction study. Crystals are monoclinic, space group P2₁/n, with Z  4 in a unit cell of dimensions a  13.761(4), b  21.653(13), c  17.395(6) Å, β,  104.46(2)°. The structure has been solved and refined to R  0.064 (R′  0.064) for 3139 independent diffracted intensifies measured at room temperature. The platinum atom is in a trigonal environment formed by the two ligated phosphorus atoms and the CC bond of the fulvene which is elongated to 1.52(3) Å. The c₅ fulvene ring is planar, and makes an angle of 108° with the coordination plane around the platinum. In this plane the metal atom is slightly asymmetrically bonded with PtC 2.15(2) and 2.24(2) Å, and PtP 2.280(6) and 2.301(6) Å.     

Molybdänhalogenidcluster mit zwei terminalen Alkoholatliganden: Synthese und Kristallstrukturen von (C18H36N2O6Na)2[Mo6Cl12(OCH3)2] und (C18H36N2O6Na)2[Mo6Cl12(OC15H11)2] · 2C4H6O3

Molybdenum(II) Halide Clusters with two Alcoholate Ligands: Syntheses and Crystal Structures of (C₁₈H₃₆N₂O₆Na)₂[Mo₆Cl₁₂(OCH₃)₂] and (C₁₈H₃₆N₂O₆Na)₂[Mo₆Cl₁₂(OC₁₅H₁₁)₂] · 2C₄H₆O₃ . Reaction of Mo₆Cl₁₂ with two equivalents of sodium methoxide in the presence of 2,2,2-crypt yields (C₁₈H₃₆N₂O₆Na)₂[Mo₆Cl₁₂(OCH₃)₂] ( 1 ), which can be converted to (C₁₈H₃₆N₂O₆Na)₂[Mo₆Cl₁₂(OC₁₅H₁₁)₂] · 2C₄H₆O₃ ( 2 ) by metathesis with 9-Anthracenemethanole in propylene carbonate. As confirmed by X-ray single crystal structure determination ( 1 : C2/m, a=25.513(8) Å, b=13.001(3) Å, c=10.128(3) Å, β=100.204(12)°; : C2/c, a=15.580(5) Å, b=22.337(5) Å, c=27.143(8) Å, β=98.756(10)°) the compounds contain anionic cluster units [Mo₆ClCl(OR^a)₂]^2? with two alcoholate ligands in terminal trans positions ( 1 : d(Mo—Mo) 2.597(2) Å to 2.610(2) Å, d(Mo—Clⁱ) 2.471(3) Å to 2.493(4) Å, d(Mo—Cl^a) 2.417(8) Å and 2.427(8) Å, d(Mo—O) 2.006(13) Å; 2 : d(Mo—Mo) 2.599(3) Å to 2.628(3), d(Mo—Clⁱ) 2.468(8) Å to 2.506(7) Å, d(Mo—Cl^a) 2.444(8) Å and 2.445(7) Å, d(Mo—O) 2.012(19) Å).     

Synthesis and structure of FeRu3(CO)13(μ-PPh2)2; A “64-electron” cluster complex with a planar triangulated rhomboidal array of metal atoms

The species FeRu₃(CO)₁₃(μ-PPH₂)₂, synthesized from Ru₃(CO)₁₂ and Fe(CO)₄(Ph₂PPPh₂),has been characterized both spectroscopically and via a single-crystal X-ray structural analysis. This complex crystallizes in the centrosymmetric triclinic space group P$\text{1}$ [No. 2, C_i¹] with a  10.066(3), b  12.899(3), c  17.003(4) Å, α  111.89(2), β  91.02(2), γ  102.00(2)°, V  1992.7(9) ų, Z  2, ?(obsd)  1.79(2) g cm^-3 and ?(calcd)  1.82 cm^-3. Diffraction data were collected with a Syntex P2₁ automated four-circle diffractometer and the structure was refined to R_F  6.0% and R_WF  3.6% for all 5213 reflections (R_F  3.8%, R_WF  3.6% for those 4140 reflections with |F_o|> 3σ(|F_o|).The metal atoms define a planar triangulated rhombus, with atoms Ru(1) and Ru(2) at the bridgehead, and Fe(1) and Ru(3) at the acute apices. Fe(1) is linked to four terminal carbonyl ligands and is associated with the heteronuclear bonds Fe(1)Ru(1)  2.861(1) Å and Fe(1)Ru(2)  2.868(1) Å. The ruthenium atoms are each bonded to three terminal carbonyl groups. The retheniumruthenium distances are Ru(1)Ru(2)  3.098(1), Ru(1)Ru(3)  3.147(1), and Ru(2)Ru(3)  3.171(1) Å. The structure is completed by Ph₂P bridges across the Ru(1)Ru(3) and Ru(2)(ru(3) vectors (<Ru(1)P(1)Ru(3)  84.89(5)° and <Ru(2)P(2)Ru(3)  85.56(6)°).     

Study of new molecular and crystal structures of 4,4,10,10-tetramethyl-1,3,7,9-tetraazospiro[5.5]undecane-2,8-dione and its salts: Monochloride,mononitrate, and tetraiodotellurate

This is the first work to synthesize 4,4,10,10-tetramethyl-1,3,7,9-tetraazospiro[5.5]undecane-2,8-dione monohydrate, monochloride, mononitrate, and teteraiodotellurate: C₁₁H₂₀N₄O₂·H₂O (I), C₁₁H₂₁N₄O ₂ ⁺ ·Cl^? (II), C₁₁H₂₁N₄O ₂ ⁺ ·NO ₃ ^? (III), and 2(C₁₁H₂₁N₄O ₂ ⁺ )·TeI ₄ ^2? ·C₃H₆O (IV) and determine their structures. Crystals of I are monoclinic: space group P2₁/c, at 298 K a = 5.7118(7) Å, b = 17.842(2) Å, and c = 13.5905(16) Å; β = 91.621(11)°; V = 1384.5(3) ų; d _x = 1.239 g/cm³, Z = 4. Crystals of II are tetragonal: space group P4₃, at 298 K a = 6.4134(3) Å and c = 34.292(2) Å; V = 1410.47(14) ų; d _x = 1.303 g/cm³; Z = 4. Crystals of III are triclinic: space group \(P\bar 1\) , at 298 K a = 8.7614(14) Å, b = 9.3904(18) Å, and c = 10.028(2) Å; α = 63.27(2)°, β = 78.591(16)°, and γ = 84.308(15)°; V = 722.3(2) ų; d _x = 1.40 g/cm³; Z = 2. Crystals of IV are triclinic: space group \(P\bar 1\) , at 100 K a = 10.4630(4) Å, b = 11.9372(6) Å, and c = 16.4118(5) Å; α = 72.058(3)°, β = 76.406(3)°, and γ = 87.029(3)°; V = 1895.04(12) ų; d _x = 2.06 g/cm³; Z = 2. The synthesis of s and p metals with spirocarbone in acetone medium is found to be impossible due to the protonation by the oxygen atom of the carbonyl group. The main crystalline product of the complexation reaction is a monosalt. Evidence is provided that the recrystallization and drying of the synthesized spirocarbone preparation yields monohydrate (I); its purity and monophasity is confirmed by a Rietveld refinement of the powder X-ray pattern. The lattice parameters at room temperature are: a = 5.6885(12) Å, b = 17.8496(12) Å, and c = 13.518(3) Å; β = 91.449(15)°; V = 1372.1(4) ų. The sample is monophasic.     

The crystal and molecular structure of tris[(triphenylstannyl)methyl]methane

The title compound, C₅₈H₅₂Sn₃, belongs to the triclinic space group P$\text{1}$, with a 10.165, b 13.365, c 18.670 Å, α 96.28, β 93.88, γ 103.15°, V = 2443.8 ų, f_w = 1105.1, Z = 2, D_calc 1.501 g cm^?3, m.p. 206.5–208°C, λ(Mo-K_$\text{α}$) 0.71069 Å. The structure was refined on 2684 nonzero reflections to an R factor of 0.044. The crystal contains molecules in which the (SnCH₂)₃CH core possesses an approximate C₃ symmetry. The three SnC(H₂) bonds are gauche to the C(4)-H bond. Repulsive interactions involving the bulky Ph₃Sn substituents lead to large SnC(H₂)C(H) angles (av. 117.3°), whereas the C(H₂)C(H)C(H₂) angles at the tertiary carbon average 111.3°. Little distortion of the Ph₃Sn groups themselves is present, since the PhSnPh angles (av. 109.8°) are almost equal to the C(H₂)SnPh angles (av. 109.9°). The molecule as a whole has no symmetry because the aromatic rings in the three Ph₃Sn groups have different orientations. The phenyl groups create a pocket in the middle of the molecule which encloses and shields the tertiary hydrogen atom. The resulting inaccessibility of this hydrogen accounts in part for the low reactivity of the title compound in redox reactions.     

Synthesis and characterization of the organoimidopolyoxomolybdates [ n -Bu4N]2[Mo6O17(≡NAr)2] (Ar = 2-ethyl-6-methylphenyl and 2-isopropyl-6-methylphenyl)

Two new bifunctionalized arylimido derivatives of hexamolybdate, [n-Bu₄N]₂[Mo₆O₁₇(C₆H₃N-2-C₂H₅-6-CH₃)₂] (1) and [n-Bu₄N]₂[Mo₆O₁₇(C₆H₃N-2-CH(CH₃)₂-6-CH₃)₂]?·?H₂O (2), in which the two organoimido groups are covalently bonded to hexamolybdate at the cis positions, were synthesized by self-assembled metathesis of α-octamolybdate and organoimido ligands with N,N′-dicyclohexylcarbodiimide as dehydration agent, and characterized by elemental analysis, ¹H NMR, IR and electronic spectroscopy, and X-ray diffraction analysis. Both derivatives have short Mo–N bond distances [Mo(1)–N(1), 1.740(3)?Å; Mo(2)–N(2), 1.739(3)?Å for 1 and Mo(1)–N(1), 1.734(3)?Å; Mo(2)–N(2), 1.741(3)?Å for 2] and form dimers via π–π stacking in the crystalline state.     

Synthesis and structure of [C3N2H5][Cu(H2PO4)2Cl]·H2O with a chain structure: the first example of an organically templated copper (II) phosphate

A new one-dimensional copper (II) phosphate, [C₃N₂H₅][Cu(H₂PO₄)₂Cl]·H₂O, I, with pseudo-10-membered channels along the b-axis formed by the hydrogen bonded chains, containing imidazolium ions has been synthesized and characterized by single-crystal X-ray diffraction. The compound being the first example of an organically templated copper (II) phosphate, crystallizes in the monoclinic space group P2₁/n (No. 14) with a=8.9998(14) Å, b=7.0189(11) Å, c=18.986(3) Å; β=102.964(3)°; V=1168.8(3) ų; Z=4. The copper chlorophosphate chains in I are topologically similar to those observed in fornacite and vauquelinite.     

Synthesis and structure of platinum complexes [Ph4P]+[PtCl3(DMSO)]− and [Ph4P]+[PtCl5(DMSO)]−

The reaction of tetraphenylphosphonium chloride with an equimolar amount of potassium tetrachloroplatinate or hexachloroplatinic acid in dimethyl sulfoxide gave the complexes [Ph₄P]⁺[PtCl₃(DMSO)]^? (I) and [Ph₄P]⁺[PtCl₅(DMSO)]^? (II), respectively. The phosphorus atoms in the cations have tetrahedral environment, the CPC angles and P-C distances 105.63(13)°–112.13(14)°, 1.795(3)–1.797(3) Å I) and 105.7(3)°–112.9(3)°, 1.783(7)–1.791(6) Å II). The platinum coordination polyhedra in the anions [PtCl₃(DMSO)]^? and [PtCl₅(DMSO)]^? are distorted square (Pt-S, 2.1937(8); Pt-Cl, 2.2894(10)–2.3024(10) Å; trans-angles: SPtCl, 177.38(4)°; ClPtCl, 175.40(4)°) and octahedron (Pt-S 2.291(2) Å; Pt-Cl, 2.312(2)–2.334(2) Å, trans-angles: SPtCl, 178.28(9)°; ClPtCl, 178.80(9)° and 178.88(8)°).     

Carbon-13 nuclear magnetic resonance studies of some phosphonium,arsonium, sulfonium and pyridinium keto-stabilized salts,and ylides and of their palladium(II) complexes

The ¹³C chemical shifts, the ¹³C³¹P coupling constants, and some one-bond ¹³C¹H coupling constants were measured for the title compounds. For the ylides of phosphorus, arsenic and sulfur, the data are consistent with an sp²-hybridized ylidic carbon with a strong, localized negative charge, while for the pyridinium ylide this charge is much more delocalized. in the homologous series of salts the electron-withdrawing ability of the groups studied varies in the order: Ph₃P⁺ < Ph₃As⁺ « Me₂S⁺ « Me₂C₅H₃N⁺. The differences in the carbonyl chemical shift between the ylides and the corresponding salts are a measure of the resonance stabilization of the negative charge in the form X⁺CCO^?; this stabilization varies with the groups studied in the order: Ph₃P⁺ < Ph₃As⁺ ≈ Me₂S⁺ « Me₂C₅H₃N⁺. The ylide—palladium(II) complexes contain a bond between the ylidic carbon and the metal: the ylidic carbon is shifted upfield in the complex with respect to the free ligand, while the adjacent carbonyl is shifted strongly downfield. These data suggest that the PdC(1) bond is strongly polarized with a high electron density on the C(1) atom which cannot be delocalized through resonance as in the free ligands.     

Reactions of triphenylbenzylphosphonium and tetraphenylstibonium chlorides with potassium tetrachloroplatinates in dimethylsulfoxide

Platinum complexes [Ph₃PhCH₂P]⁺[(Me₂S=O)PtCl₃]^? I and cis-Cl₂(Ph₃Sb)(Me₂S=O)Pt II were synthesized by reaction of triphenylbenzylphosphonium and tetraphenylstibonium chlorides with potassium tetrachloroplatinate in DMSO. Crystal I is formed by triphenylbenzylphosphonium tetrahedral cations [P-C_Ph 1.791(4)-1.795(4) Å, P-C_Alk 1.811(4) Å; CPC 107.57(18)°-111.46(17)°] and by square anions [(Me₂S=O)PtCl₃]^? [Pt-Cl 2.3236(11), 2.2981(12), 2.2977(11) Å; Pt-S 2.1950(10) Å; trans-angles SPtCl 177.51(4)°, ClPtCl 178.74(4)°]. In a square-planar complex II [trans-angles SPtCl 178.01(6)°, ClPtSb 177.96(4)°] with central platinum atom the chlorine atoms [Pt-Cl 2.308(1), 2.350(1) Å], triphenylstibine [Pt-Sb 2.5118(4) Å] and dimethyl sulfoxide [Pt-S 2.195(1) Å] molecules are coordinated. Compound II is a first example of mixed ligand complex of platinum(II), where in the coordination sphere of central atom the tertiary stibine is present along with DMSO ligand.     

The synthesis and crystal structure of a trinuclear molybdenum cluster compound [Mo3(μ-O)(μ-S)3(μ(μ-OAc)2(dtp)2·(Py)]·0.5H2O

[Mo₃,OS₃(dtp)₄(H₂O)] reacts with NaOAc·3H₂O in Py to give the title compound. The crystal data are as follows: [Mo₂OS₃)(OAc)₂(dtp)₂·Py]?0.5H,O(dtp = [S₃P(OC₂H₅)₂]^?, Py = C₅H₅N); M = 976.64; triclinic; space group P1 ; a=11.704(5), b=14.169(7), c= 11.688 (5) Å α=109.94(4) β = 91.53(4), γ = 91.93(4)°; V= 1819(1) Ų; Z=2; D_c = 1.78 g·cm^?3 λ(Mo Kα) = 0.71069 Å μ=15.15 cm^?1; F(000) = 970 T=296 K; final R=0.071 for 1652 reflections with I>3σ(I). In the molecule, the [Mo₃OS₃] core is surrounded by two bridging OAc groups and two terminal chelate dtp groups attached to the {Mo₃} triangle in a symmetric style, and the Py ligand is coordinated to the Mo atom at the apex of {Mo₃} triangle with the nitrogen. This novel configuration is obtained for the first time with Mo—N bond length being 2.27 (2) Å and three Mo—Mo bond lengths 2.584 (4), 2.587 (4) and 2.657(4) Å, respectively. As a whole, the molecule has a virtual C₂ symmetry.     

Preparation and Reactivity of Mo(NCMe)(η2‐C2Ph2)2(η4‐C4Ph4)

Reaction of Mo(CO)(η²‐C₂Ph₂)₂(η⁴‐C₄Ph₄) and Me₃NO in acetonitrile solvent affords Mo(NCMe)(η²‐C₂Ph₂)₂(η⁴‐C₄Ph₄) 1 . Compound 1 reacts with trimethylphosphine to produce Mo(PMe₃)(η²‐C₂Ph₂)₂(η⁴‐C₄Ph₄) 2 , or reacts with diphenylacetylene to produce (η⁵‐C₅Ph₅)₂Mo 3 and Mo(η²‐O₂CPh)(η⁴‐C₄Ph₄H)(η⁴‐C₄Ph₄) 4 . The molecular structures of 1, 2 and 4 have been determined by an X‐ray diffraction study.