Bridging and chelating diphosphine ligands in Ru3(μ-H)(μ-N=CPh2)(CO)8(P—P). X-ray diffraction structures of Ru3(μ-H)(μ-N=CPh2)(CO)8(dmpe) and Ru3(μ-H)(μ-N=CPh2)(CO)8(bpcd)

Treatment of the azavinylidene-bridged cluster Ru₃(-H)(-N=CPh₂)(CO)₁₀ (1) with the diphosphine ligand bis(dimethylphosphino)ethane (dmpe) gives Ru₃( -H)(-N=CPh₂)(CO)₈(dmpe) (2) in moderate yield, while the ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) reacts with Ru₃( -H)(-N=CPh₂)(CO)₁₀ in the presence of Me₃NO to furnish Ru₃( -H)(-N=CPh₂)(CO)₈(bpcd) (3) in low yield. Each new cluster has been isolated and characterized in solution by IR and NMR (¹H and ³¹P) spectroscopies, and the coordination mode exhibited by the ancillary diphosphine ligand in 2 and 3 has been established by X-ray crystallography. Ru₃( -H)(-N=CPh₂)(CO)₈(dmpe) crystallizes in the monoclinic space group P2(1)/c, a = 10.791(1) Å, b = 16.377(1) Å, c = 18.148(1) Å, = 96.675(2)°, V = 3185.3(4) ų, Z = 4, D _cacl = 1.791 Mg/m³; R = 0.0360, R _w = 0.0866 for 7522 observed reflections with I > 2(I). Ru₃(-H)(-N=CPh₂)(CO)₈(bpcd) crystallizes, as the CH₂Cl₂ solvate, in the triclinic space group , a = 11.956(1) Å, b = 14.228(1) Å, c = 31.409(3) Å, = 89.377(2)°, = 79.344(2)°, = 77.235(2)°, V = 5118.4(8) ų, Z = 2, D _calc = 1.670 Mg/m³; R = 0.0557, R _w = 0.1069 for 10977 observed reflections with I > 2(I). The structural details of clusters 2 and 3 are contrasted with Ru₃(-H)(-N=CPh₂)(CO)₇(-dppm)(-dppm), which is the only known structurally characterized phosphine-substituted cluster of this genre.     

Alkyne insertion and coupling reactions of methyl propiolate with the heterometallic dimers CoRu(CO)7(μ-PPh2) and CoRu(CO)5[(Z)-Ph2PCH = CHPPh2](μ-PPh2): X-ray diffraction structures of CoRu(CO)4(μ-CO)[μ-PPh2C(O)CH(CCO2Me)C(O)CHC (CO2Me)] and CoRu(CO)3(μ-CO)[(Z)-Ph2PCH = CHPPh2][μ-PPh2C(O)C(CO2Me)CH]

The reaction of the terminal alkyne methyl propiolate with the heterometallic dimers CoRu(CO)₇(μ-PPh₂) (1) and CoRu(CO)₅[(Z)-Ph₂PCH=CHPPh₂](μ-PPh₂) (2) has been investigated at 65^°C in toluene. In the reaction of 1, chromatographic purification afforded a minor band, from which the two species RuCo(CO)₄(μ-CO)[μ-PPh₂C(O)CHC(CO₂Me)] and RuCo(CO)₄(μ-CO)[μ-PPh₂CHC(CO₂Me)] were observed by ¹H NMR spectroscopy, and one major band, whose ¹H NMR spectrum revealed the presence of multiple species. The identity of one of the compounds in the major component has been established as that of CoRu(CO)₄(μ-CO)[μ-PPh₂C(O)CH(CCO₂Me)C(O)CHC(CO₂Me)] (3) by X-ray diffraction analysis. The solid-state structure of 3 confirms the double insertion of CO and head-to-head coupling of the methyl propiolate that accompanies the formation of this product. Compound 3 crystallizes in the triclinic space group P-1, a = 8.4035(4), b = 9.6721(5), c = 17.678(1) Å, α = 94.135(2), β = 103.318(2), γ = 101.336(2)^°, V = 1360.5(1) ų, Z = 2, D _calc = 1.732 Mg/m³; R = 0.0300, R _w = 0.0760 for 8630 reflections with I > 2σ(I). The ruthenium-bound diphosphine ligand in 2 exerts a controlling influence on the reaction with added alkyne insomuch as only the mono-insertion product CoRu(CO)₃(μ-CO)[(Z)-Ph₂PCH=CHPPh₂][μ-PPh₂C(O)C(CO₂Me)CH] (4) is formed as a single regioisomer. The molecular structure of 4 was established by X-ray diffraction analysis and 4 was found to crystallize in the monoclinic space group P2₁/c, a = 19.483(7), b = 11.905(4), c = 20.131(7) Å, β = 110.455(6)^°, V = 4375(3) ų, Z = 4, D _calc = 1.466 Mg/m³; R = 0.0961, R _w = 0.1683 for 6262 reflections with I > 2σ(I). The reactivity of methyl propiolate with 1 and 2 is compared with the known reactivity that has been reported for other alkynes.     

Regiospecific CO substitution in (μ-H)Ru3(μ3− η3-CHCHCMe)(CO)9 by 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione(bpcd). X-ray structure of (μ-H)Ru3(μ3−η3-CHCHCMe)(CO)7(bpcd)⋅MeOH

The triruthenium cluster ( -H)Ru₃( ₃–³-CHCHCMe)(CO)₉ reacts with the diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) in the presence of Me₃NO to afford ( -H)Ru₃( ₃– ³-CHCHCMe)(CO)₇(bpcd) in moderate yield. This new cluster has been isolated and characterized in solution by IR and NMR (¹H, ³¹P) spectroscopies, and the solid-state structure has been established by X-ray crystallography. ( -H)Ru₃( ₃– ³-CHCHCMe)(CO)₇(bpcd) MeOH crystallizes in the triclinic space group P , a = 11.2426(8) Å, b = 11.7141(8) Å, c = 16.195(1) Å, = 102.041(5)°, = 95.128(5)°, = 102.553(6)°, V = 2008.4(3) ų, Z = 2, d _calc. = 1.733 g/cm³; R = 0.0488, R _w = 0.0546 for 2212 observed reflections with I > 3 (I). The X-ray structure reveals that the bpcd ligand is bound exclusively to the Ru₃ core at the ruthenium center coordinated by the terminal CH unit of the -allylic ₃– ³-CHCHCMe moiety.     

Site-selective ligand substitution in CoRu(CO)7(μ-PPh2) using (Z)-Ph2PCH=CHPPh2 and reactivity of DMAD with CoRu(CO)5[(Z)-Ph2PCH=CHPPh2](μ-PPh2). X-ray structures of CoRu(CO)5[(Z)-Ph2PCH=CHPPh2](μ-PPh2) and CoRu(CO)3(μ-CO)[(Z)-Ph2PCH=CHPPh2] [μ, η3-Ph2PC(CO2Me)C(CO2Me)]

The heterometallic complex CoRu(CO)₇(μ-PPh₂) (1) reacts with the diphosphine ligand (Z)-Ph₂PCH=CHPPh₂ under both thermolysis and Me₃NO activation to furnish CoRu(CO)₅[(Z)-Ph₂PCH=CHPPh₂](μ-PPh₂) (2) in good yield. Treatment of 2 with dimethyl acetylenedicarboxylate (DMAD) at elevated temperature leads to the formal insertion of the DMAD ligand into the Co–phosphido bond and formation of the metallocyclic compound CoRu(CO)₃(μ-CO)[(Z)-Ph₂PCH=CHPPh₂][μ,η³-Ph₂PC(CO₂Me)C(CO₂Me)] (3) that contains a 5e^? alkenylphosphine moiety. These new CoRu compounds have been isolated by chromatography and fully characterized in solution by IR and NMR (¹H and ³¹P) spectroscopies, and the solid-state structures of both 2 and 3 have been determined by X-ray diffraction analysis. CoRu(CO)₅[(Z)-Ph₂PCH=CHPPh₂](μ-PPh₂) crystallizes in the monoclinic space group P2 ₁/n, a = 11.493(8), b = 20.24(1), c = 17.04(1) Å, β = 91.03(1)°, V = 3964(5) ų, Z = 4, D _calc = 1.477 Mg/m³; R = 0.0475, R _w = 0.1054 for 5120 observed reflections with I > 2σ (I). CoRu(CO)₃(μ-CO)(Z)-Ph₂PCH=CHPPh₂][μ,η³-Ph₂PC(CO₂Me)C(CO₂Me)], as the CH₂Cl₂ solvate, crystallizes in monoclinic space group P2 ₁/c, a = 17.0307(9) Å, b = 11.2124(6) Å, c = 24.083(1) Å, β = 97.755(1)°, V = 4556.8(4) ų, Z = 4, D _calc = 1.579 Mg/m³; R = 0.0379, R _w = 0.0609 for 10774 observed reflections with I > 2σ(I). The regioselective coordination of the (Z)-Ph₂PCH=CHPPh₂ ligand to the two equatorial sites of the ruthenium center in 2 and the presence of the metallocyclic alkenylphosphine ligand in 3 are confirmed by the structural studies. The regiochemistry found in the coordination of (Z)-Ph₂PCH=CHPPh₂ to 1 is contrasted with the related diphosphine ligands bma and bpcd, while the DMAD insertion reactivity with 2 is discussed relative to alkyne reactions reported for the parent compound CoRu(CO)₇(μ-PPh₂).     

Synthesis and X-ray structure of [(μ-H)Os3(CO)10(μ-η2-N=CCH=CHCH=CC2H5)]

The reaction of [Os₃(CO)₁₀(MeCN)₂] with 2-ethylpyridine at ambient temperature leads to the isolation of the cluster [(-H)Os₃(CO)₁₀(-²-N=CCH=CHCH=CC₂H₅)][3 (65% yield) which has been structurally characterized by crystallographic methods. The compound crystallizes in the triclinic space group with a = 9.334(2), b = 9.918(2), c = 11.767(1) Å, = 92.13(2), = 99.93(1), = 99.88(2)°, V = 1054.7(3) ų and Z = 2. The same edge of the osmium triangle in the cluster is bridged by both the hydrido and the heterocyclic ligands, the latter through the nitrogen and the carbon atoms of the C=N bond.     

Chelation of a diphosphine ligand at FeCo2(CO)9(μ3-S): Spectroscopic and X-ray diffraction data for FeCo2(CO)7(bpcd)(μ3-S)

The tetrahedrane cluster, FeCo₂(CO)₉(₃-S), reacts with the redox-active ligand, 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd), to give the disubstituted cluster, FeCo₂(CO)₇(bpcd)(₃-S), as the sole product. This diphosphine-substituted cluster contains a cobalt-bound, chelating bpcd ligand. Both IR and ³¹P NMR spectroscopies have been employed in the solution characterization of FeCo₂(CO)₇(bpcd)(₃-S), and the solid-state structure has been unequivocally established by X-ray diffraction analysis. FeCo₂(CO)₇(bpcd)(₃-S) crystallizes in the monoclinic space group C2/c, a = 34.494(3) Å, b = 11.4194(9) Å, c = 18.634(2) Å, = 98.103(7)°, V = 7266.7(9) ų, Z = 8, and d_calc = 1.584 g/cm³. Cyclic voltammetric studies on FeCo₂(CO)₇(bpcd)(₃-S) reveal the presence of two quasireversible redox responses assigned to the 0/1^– and 1^–/2^– redox couples. The orbital composition of these redox couples has been examined by carrying out extended Hückel MO calculations on the model complex FeCo₂(CO)₇(H₄-bpcd)(₃-S), with the results being compared to related cluster compounds.     

Reaction between [Ru3(CO)10(μ-dppm)] (dppm = Ph2PCH2PPh2) and Te2(C6H4OEt-4)2: X-ray crystal structure of [Ru2(CO)6{μ-C6H4PPh(CH2)PPh}]

Treatment of [Ru₃(CO)₁₀(-dppm)] (1) with the ditelluride Te₂(C₆H₄OEt-4)₂ in refluxing toluene afforded the new aryltellurol bridged complex [Ru₂(CO)₄(-TeC₆H₄OEt-4)₂ (-dppm)] (2) together with three known complexes [Ru₄(CO)₈(-CO)(₄-Te)₂(-dppm)] (3), [Ru₂(CO)₆{-CH₂PPh(C₆H₄)PPh}] (4), and [Ru₂(CO)₆{-C₆H₄PPh(CH₂)PPh}] (5). All the four complexes were characterized by spectroscopic methods, including an X-ray structure determination for 5. Complex 5 crystallizes in the monoclinic space group P2₁/c with a = 13.650(2), b = 9.995(2), c = 18.929(3) Å, = 97.49(2)°, V = 2560.4(8) ų, and Z = 4. In this complex the two ruthenium atoms are bridged by the phosphino-phosphide ligand C₆H₄PPh(CH₂)PPh which is attached to one Ru by the C₆H₄ group and a P atom while to the other Ru by both the two P atoms. Both the ruthenium atoms show distorted octahedral geometry. The Ru—Ru bond length is 2.8719(7) Å.     

Synthesis and X-ray structure of [(μ-H)Ru3(CO)8(μ-Cl)(μ-dppm)] [dppm = bis(diphenylphosphino)methane]

The reaction of [Ru₃(CO)₁₀(-dppm)] 1 with PPhCl₂ in refluxing CHCl₃ results in the isolation of [(-H)Ru₃(CO)₈(-Cl)(-dppm)] 3 in 10% yield. Compound 3, which has been structurally characterized by crystallographic methods, is also formed from the reaction of 1 with H₂ in refluxing CCl₄. The compound crystallizes in the monoclinic space group P2₁/c with a = 16.814(2), b = 18.7590(12), c = 11.486(2) Å, = 97.745(11)°, V = 3589.8(8) ų, and Z = 4. The hydride and chloride ligands bridge the same edge of the triruthenium cluster as the dppm ligand.     

Synthesis and structural analysis of (μ-SCH2CH2CH2S-μ)Fe2(CO)5(2-C5H4NPPh2)

Treatment of (μ-SCH₂CH₂CH₂S-μ)Fe₂(CO)₆ with equimolar 2-C₅H₄NPPh₂ in the presence of Me₃NO·2H₂O in CH₂Cl₂/MeCN solutions gave the title complex (μ-SCH₂CH₂CH₂S-μ)Fe₂(CO)₅(2-C₅H₄NPPh₂) in 76% yield. The title complex was characterized by spectroscopy as well as by single crystal X-ray diffraction analysis. The molecular structure consists of a butterfly [Fe₂S₂] cluster with propane, five carbonyls, and 2-C₅H₄NPPh₂. In the crystal packing diagram, intermolecular C–H···O hydrogen bonds between phenyl and carbonyl groups stabilize the solid state.     

Carbon–hydrogen and carbon–phosphorus bond cleavage in a triruthenium cluster complex containing dppm: The crystal and molecular structures of Ru3(CO)6{μ 3-OPPh2 C2H(C6H4)PPhCH2PPh}(μ 3-OPPh2)Ph and Ru3(CO)6 {μ-OPPh2C2H(C6H4)PPhO}(μ-PPh2)(μ-PPh2O)

The crystal and molecular structures of Ru₃(CO)₆{μ ₃-OPPh₂C₂H(C₆H₄)PPhCH₂PPh}-(μ ₃-OPPh₂)Ph (1) and Ru₃(CO)₆{μ-OPPh₂C₂H(C₆H₄)PPhO}(μ-PPh₂)(μ-PPh₂O) (2) have been determined by single crystal X-ray diffraction. Both complexes contain oxygen atoms oxidatively inserted into phosphorus–ruthenium bonds, and unique σ/π multidentate ligands formed from C $---{\text{H}}$ H and C $--$ P bond cleavage in bis(diphenylphosphino)acetylene and bis(diphenylphosphino)methane. Complex 1 crystallized in the triclinic space group ${\bar 1}$ , with lattice parameters a = 11.642(4) Å, b = 15.018(5) Å, c =16.587(5) Å, α = 2.48(3)°, β = 76.47(2)°, γ = 70.35(3)°, V = 2651.1(15) ų, Z = 2. Complex 2 crystallized in the centered monoclinic space group, C2/c, with lattice parameters a = 34.467(4) Å, b = 14.274(2) Å, c = 23.258(3) Å, β = 5.29(1)°, V = 11394(3) ų, Z = 8.     

CO replacement in Ru3(CO)12 by 2,3-bis(diphenylphosphino)maleic anhydride (bma). X-ray structures of Ru3(CO)10(bma)·H2O and

Thermolysis of Ru₃(CO)₁₂ with 2,3-bis(diphenylphosphino)maleic anhydride (bma) in toluene solution gives the new compounds Ru₃(CO)₁₀(bma) (2), Ru₂(CO)₆(bma) (3), and (4). All compounds have been isolated and characterized in solution by IR and³¹P NMR spectroscopy. The solid-state structures of2, as the monohydrate, and4 were established by X-ray crystallography. Ru₃(CO)₁₀(bma)·H₂O crystallizes in the monoclinic space groupC2/c,a=12.741(2) Å,b=19.548(2) Å,c=32.973(4) Å, β=96.847(9)°,V=8154(2) ų,Z=8,d _calc=1.740 g cm^?3;R=0.046,R _w =0.051 for 2541 observed reflections withl>3σ(l). The bma ligand in2 is bound to the triruthenium frame in a bridging fashion, with equatorially disposed PPh₂ groups. The X-ray structure of2 reveals an extreme twisting of the maleic anhydride ring away from the plane defined by the plane of the three ruthenium atoms, along with a significant lengthening of the maleic anhydride C=C π bond. crystallizes in the monoclinic space groupP2₁/c,a=9.3113(5) Å,b=18.164(1) Å,c=20.097(1) Å, β-102.021(4)°,V=3324.5(3) ų,Z=4,d _calc=1.671 g cm^?3;R=0.024,R _w =0.030 for 3499 observed reflections withl>3σ(l). The presence of the μ₂ moiety and P?C (maleic anhydride) bond cleavage attendant in the formation of4 are confirmed by X-ray analysis. The relationship of the compounds3 and4 to the dimeric compounds Ru₂(CO)₆(bpcd) and [where bpcd=4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione] is discussed. Independent studies dealing with Ru₃(CO)₁₀(bma) (bridging isomer) have shown that cluster2 is stable in toluene solution at elevated temperature and does not afford compounds3 and4, suggesting the intermediacy of the putative chelating isomer of Ru₃(CO)₁₀(bma) (1) as the source of3 and4.     

Reaction of bis(dimethoxyphosphino)dimethylhydrazine (dmpdmh) with Ru3(CO)12: Evidence for facile ligand fragmentation in Ru3(CO)10(dmpdmh) to give Ru4(CO)12[μ-N(Me)N(Me)], Ru3(CO)11[P(OMe)3], and Ru3(CO)9[μ-P(OMe)3]

Thermolysis of the cluster Ru₃(CO)₁₂ with the bis(phosphanyl)hydrazine ligand (MeO)₂PN (Me)N(Me)P(OMe)₂ (dmpdmh) in toluene at 75°C furnishes the known clusters Ru₄(CO)₁₂ [-N(Me)N(Me)] (2) and Ru₃(CO)₁₁[P(OMe)₃] (3), in addition to the new cluster Ru₃ (CO)₁₀(dmpdmh) (1) and the phosphite-tethered cluster Ru₃(CO)₉[-P(OMe)₃] (4). The simple substitution product Ru₃(CO)₁₀(dmpdmh), a logical intermediate to clusters 2–4, was synthesized by treating Ru₃(CO)₁₂ with Me₃NO in CH₂Cl₂ at room temperature, and independent thermolysis reactions using cluster 1 was shown to yield clusters 2–4. The solid-state structure of clusters 2 and 4 were unequivocally established by X-ray diffraction analysis. Ru₄(CO)₁₂[-N(Me)N(Me)] crystallizes in the orthorhombic space group Pnna (#52), a = 12.913(1), b = 13.3238(6), c = 12.5690(8) Å, V = 2162.5(2) ų, Z = 4, and d _calc = 2.452 g/cm³. Ru₃(CO)₉[-P(OMe)₃] crystallizes in the triclinic space group P a = 9.586(1), b = 14.354(1), c = 14.997(2) Å, = 89.82(1)°, = 98.36(1)°, = 92.010(8)°, V = 2040.4(4) ų, Z = 4, and d _calc = 2.212 g/cm³. The coordination of the dimethylazo linkage to the four ruthenium atoms in 2 and the phosphorus atom and one of the oxygen atoms of the methoxy groups to the three ruthenium centers in 4 are confirmed by X-ray analysis.     

Thermolysis of the tetrahedrane cluster PhCCo3(CO)3(μ-CO)Cp2 with the unsaturated diphosphine ligands (Z)-Ph2PCH=CHPPh2 and 4,5-Bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd): Redox properties and molecular structure of PhCCo3(CO)(μ-CO)[(Z)-Ph2PCH=CHPPh2]Cp2

Thermolysis of the tricobalt cluster PhCCo₃(CO)₃(μ-CO)Cp₂ (1) with the diphosphine ligands (Z)-Ph₂PCH=CHPPh₂ and 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) has been examined and found to give the diphosphine-substituted clusters PhCCo₃(CO)[(Z)-Ph₂PCH=CHPPh₂](μ-CO)Cp₂ (2) and PhCCo₃(CO)(bpcd)(μ-CO)Cp₂ (3) in moderate yield. The new compounds 2 and 3 have been isolated and characterized in solution by IR and NMR (¹H and ³¹P) spectroscopies. VT ³¹P NMR data reveal that the chelating diphosphine ligand is fluxional in solution and exhibits a rocking motion between the axial and equatorial sites that renders both phosphorus moieties identical at ambient temperature. The molecular structure of PhCCo₃(CO)[(Z)-Ph₂PCH=CHPPh₂](μ-CO)Cp₂ (2) has been determined by X-ray crystallography. PhCCo₃(CO)[(Z)-Ph₂PCH=CHPPh₂](μ-CO)Cp₂ crystallizes, as the CH₂Cl₂ solvate, in the monoclinic space P2₁/n, a = 16.822(2) Å, b = 10.554(1) Å, c = 23.135(3) Å, β = 100.944(2)^°, V = 4032.4(8) ų, Z = 4, and d _calc = 1.537 Mg/m³; R = 0.0488, R _w = 0.0725 for 9431 reflections with I > 2σ(I). The solid-state structure of cluster 2 establishes the chelating nature of the ancillary (Z)-Ph₂PCH=CHPPh₂ ligand at the unique Co(CO)P₂ center via coordination at an equatorial and an axial site. The redox behavior of clusters 2 and 3 has been explored by cyclic voltammetry and chronocoulometry. Each cluster reveals the presence of two one-electron oxidations of common origin due to the oxidation of a Co–Co bonding orbital. Whereas cluster 2 does not exhibit an accessible reduction process in CH₂Cl₂, a ligand-based one-electron reduction was found for cluster 3 given its low-lying π* LUMO associated with the bpcd ligand. The electrochemical data for clusters 2 and 3 are discussed with respect to the reported redox chemistry for this genre of tricobalt cluster and the bpcd ligand.     

Self-assemblies of Ni(II) with phenanthroline and maleate anions: [Ni(H2O)3(phen)L] ⋅ H2O (1) and [Ni(H2O)2(phen)L] ⋅ 2H2O (2) with H2L = maleic acid

The complex [Ni(H₂O)₃(phen)(C₄H₂O₄)] H₂O (1), which was obtained by reaction of phenanthroline, Ni(NO₃)₂ 6H₂O, and maleic acid in CH₃OH/H₂O at pH = 7.05, crystallized in the monoclinic space group P2₁ (no. 4) with cell dimensions: a = 9.350(1) Å, b = 7.631(1) Å, c = 12.821(1) Å, = 106.25(1), and D _calc = 1.607 g/cm³ for Z = 2. The Ni atoms are each octahe drally coordinated by one chelating phen ligand, three H₂O molecules and one monodentate maleato ligand to form [Ni(H₂O)₃(phen)(C₄H₂O₄)] complex molecules with d(Ni–O) = 2.038–2.090 Å, d(Ni–N) = 2.066, 2.089 Å. The formed complex molecules are, via the intermolecular hydrogen bonds, assembled into columnar 1D chains. Interdigitation of the chelating phen ligands of the neighboring chains leads to 2D layers and the crystal H₂O molecules are hydrogen bonded to the oxygen atoms of the maleate not coordinated to the Ni atom. However, reaction of NiCO₃, phen, and maleic acid in CH₃OH/H₂O at pH = 6.33 afforded [Ni(H₂O)₂(phen)(C₄H₂O₄)] 2H₂O (2), which crystallized in the triclinic space group (no. 2) with cell dimensions: a = 7.971(1) Å, b = 8.237(1) Å, c = 13.304(1) Å, = 81.005(6)°, = 87.877(8)°, = 78.322(8)°, and D _calc = 1.671 g/cm³ for Z = 2. The Ni atoms are each octahedrally coordinated by two N atoms of one phen ligand and four O atoms of two H₂O molecules and two bis–monodentate maleato ligands with d(Ni–O) = 2.041–2.120 Å and d(Ni–N) = 2.095 Å. The Ni atoms are bridged by the maleato ligands to generate 1D ¹ [Ni(H₂O)₂(phen)(C₄H₂O₄)_2/2] chains along [100]. The supramolecular assemblies of the 1D chains via – stacking inter- actions result in thick 2D layers parallel to (001), between which the noncoordinating H₂O molecules are sandwiched. The paramagnetic [Ni(H₂O)₂(phen)(C₄H₂O₄)_2/2] 2H₂O (2) obeys the Curie–Weiss law _m(T-) = 1.139cm³ mol^–1 K with the Weiss constant = –0.95 K.     

Synthesis and X-ray structure of [(H3O)(C14H20O5)2][Me2NH2]2 [PMo12O40] · 2C14H20O5 (C14H20O5 = benzo-15-crown-5; Me2NH = dimethylamine)

[(H₃O)(C₁₄H₂₀O₅)₂][Me₂NH₂]₂ [PMo₁₂O₄₀] · 2C₁₄H₂₀O₅ 1 was synthesized from benzo-15-crown-5 and H₃PMo₁₂O₄₀·24H₂O in N,N-dimethylformamide for the first time. 1 crystallizes in the monoclinic space group C2/c with a = 18.583(4), b = 25.510(5), c = 19.904(4) Å, = 94.66(3)° D _c = 2.124 mg/m³ for Z = 4. Refinement based on 7358 observed reflections led to a R1(wR2) = 0.0378(0.0761). The complex cation, [(H₃O)(C₁₄H₂₀O₅)₂]⁺, exhibits a sandwich structure by hydrogen-bonding in the mean distance of 2.955 Å. The anion, PMo₁₂O₄₀ ^3–, is a -Keggin structure.     

Reaction of ethyl diazoacetate with Co3(CO)9(μ3-CCl): Isolation and X-ray structures of Co3(CO)9(μ3-CCO2Et), Co3(CO)9(μ3-CCH2CO2Et), and [Co3(CO)9(μ3-CCHCO2Et)]2

The reaction between the tricobalt cluster Co₃(CO)₉(₃-CCl) (1) and AlCl₃, followed by treatment with ethyl diazoacetate, N₂CHCO₂Et, affords a complex mixture of products in low yields. Column chromatography has allowed the isolation of the four cluster compounds Co₃(CO)₉(₃-CH) (2), Co₃(CO)₉(₃-CCO₂Et) (3), Co₃(CO)₉(₃-CCH₂CO₂Et) (4), and [Co₃(CO)₉(₃-CCHCO₂Et)]₂ (5). Clusters 4 and 5 are new and have been fully characterized in solution by IR and ¹H NMR spectroscopy. The molecular structures of clusters 3–5 have also been determined by single-crystal X-ray diffraction analysis. Co₃(CO)₉(₃-CCO₂Et) crystallizes in the triclinic space group P , a = 8.8393(5), b = 14.727(1), c = 15.272(1) Å, = 93.361(6), = 105.509(5)°, = 100.336(6)°, V = 1872.6(2) ų, Z = 4, and d _calc = 1.823 g/cm³. Co₃(CO)₉(₃-CCH₂CO₂Et) crystallizes in the monoclinic space group P2₁/n, a = 9.3806(7), b = 9.2617(8), c = 22.455(2) Å, = 94.483(7)°, V = 1944.9(3) ų, Z = 4, and d _calc = 1.803 g/cm³. [Co₃(CO)₉(₃-CCHCO₂Et)]₂ crystallizes in the monoclinic space group C2/c, a = 21.585(2), b = 8.7977(7), c = 20.784(1) Å, = 104.807(6)°, V = 3815.8(5) ų, Z = 4, and d _calc = 1.835 g/cm³. Plausible pathways leading to the formation of clusters 2, 4, and 5 are discussed.     

Reaction of the dicobalt alkyne compound Co2(CO)6(μ-dmad) with the diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd). Spectroscopic properties, X-ray diffraction data, and thermal reactivity of the chelating isomer of Co2(CO)4(bpcd)(μ-dmad)

Treatment of Co₂(CO)₆(-dmad) (where dmad = dimethyl acetylenedicarboxylate) with the bidentate ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) in the presence of added Me₃NO affords the new alkyne compound Co₂(CO)₄(bpcd)(-dmad) in good yield. Both IR and ³¹P NMR spectroscopies indicate that the bpcd ligand is coordinated to a single cobalt center in a chelating fashion in solution. The solid-state structure of Co₂(CO)₄(bpcd)(-dmad) is identical to the solution structure Co₂(CO)₄(bpcd)(-dmad), as determined by X-ray diffraction analysis. Co₂(CO)₄(bpcd)(-dmad) crystallizes in the triclinic space group P-1, a = 10.7460(8) Å, b = 11.628(2) Å, c = 15.077(1) Å, = 95.831(9)°, = 91.205(7)°, = 101.526(9)°, V = 1834.7(3) ų, Z = 2, and d _calc = 1.514 g/cm³; R = 0.0489, R _w = 0.0528 for 2854 reflections with I > 3(I). The thermal reactivity of Co₂(CO)₄(bpcd)(-dmad) has been briefly explored by spectroscopic methods, and evidence is presented for the attack of one of the PPh₂ groups on an alkyne carbon atom in Co₂(CO)₄(bpcd)(-dmad) to from the zwitterionic hydrocarbyl compound Co₂(CO)₄(-²:²:¹:¹-(MeO₂C)=C(CO₂Me)PPh₂C=C(PPh₂)C(O)CH₂C(O)] upon thermolysis. The redox chemistry of both Co₂(CO)₄(bpcd)(-dmad) and Co₂(CO)₄[-²:²:¹:¹-(MeO₂C) C=C(CO₂Me)PPh₂C=C(PPh₂)C(O)CH₂C(O)] has been explored by cyclic voltammetery.     

Crystal and molecular structure of octacarbonyl[bis(bispentafluorophenylarsenido)] dimolybdenum,Mo2(CO)8[μ-As(C6F5)2]2

The X-ray crystallographic structure determination of Mo₂(CO)₈[-As(C₆F₅)₂]₂ reveals that the compound crystallizes in the tetragonal space groupP42₁ c witha=14.915(3),c=16.732(3) Å,V=3722(1) ų, andZ=4. Least-squares refinement based on 1474 independent observed data [(F _obs)3(F _obs)] resulted in a finalR value of 0.038. The Mo-Mo distance of 3.132(1) Å is longer than found in analogous phosphido-bridged molybdenum systems. The central Mo₂As₂ rhombus is nearly flat and the coordination geometry of the Mo atoms is essentially octahedral. An unusual staggering of the Mo(CO)₄ groups by 15.8° and short intramolecular C₆F₅CO contacts support the presence of a strong steric interaction between the Mo(CO)₄ and As(C₆F₅)₂ groups.     

Molecular structure and hydrogen bonding of 4-dimethylaminopyridinioacetate in its crystalline dihydrate and hydrochloride trihydrate,L·2H2O and [L2H]Cl·3H2O (L=p-Me2NC5H4N+CH2CO2 −)

The crystalline dihydrate and hydrochloride trihydrate of a new betaine, namely, L·2H₂O (1) and [L₂H]Cl·3H₂O(2) (L=p-Me₂NC₅H₄N⁺CH₂CO₂), have been synthesized and characterized by X-ray crystallography. Molecule L in compound1 [space groupPbcn, witha=15.732(3),b=7.894(2),c=18.304(4) Å, andZ=8] possesses approximateC _s symmetry. The formation of hydrogen bonds by water molecules bridging neighboring carboxy oxygen atoms leads to an infinite two-dimensional network composed of a packing of two different kinds of 12-membered rings. In compound2 [space group PT witha=7.341(2),b=9.543(2),c=17.010(4) Å, =82.43(2)°, =80.34(2)°, =74.05(2)°, andZ=2], the carboxylate groups of a pair of betaine molecules are bridged by a proton to form a dimeric cation L₂H⁺ with a very strong asymmetric hydrogen bond of length 2.464(7) Å. The crystal structure features a hydrogen-bonded corrugated ribbon comprising an alternate arrangement of edge-sharing centrosymmetric (H₂O)₄(Cl^–)₂ and (H₂O)₄ rings running parallel to thea axis.     

Characterization of an asymmetric M(chelate)2(μ-Cl)2MCl2 dimer and isolation of corresponding DMSO adducts: X-ray crystal structures of Co(phen)2(μ-Cl)2CoCl2⋅C4H8O and M(chelate)Cl2(DMSO) x (Co, x = 1; Ni, x = 2) complexes

In aqueous solution, [M(chelate)Cl₂]x (chelate = 2,2-bipyridine, 1,10-phenanthroline) complexes can disproportionate to produce M(chelate)₂ ⁿ⁺ species that contain two chelating ligands. After extraction with organic solvent,Co(phen)₂(-Cl)₂CoCl₂(1) has been characterized by X-ray diffraction (monoclinic, C2/c, a = 10.278(2)Å, b = 22.026(5)Å, c = 12.941(3)Å, = 103.959(4)°, Z = 4, 2414 reflections [I 2 (I)], R ₁ = 0.0321, wR ₂ = 0.0864). However, addition of [M(chelate)Cl₂]x starting materials to dimethyl sulfoxide produces complexes that retain a single chelate ligand. The pentacoordinate complex Co(bpy)Cl₂DMSO (2) has been structurally characterized (triclinic, P , a = 7.824(2)Å, b = 9.570(4)Å, c = 10.025(2)Å, = 83.24(3)°, = 87.14(2)°, = 83.35(3)°, Z = 2, 2455 reflections [I 2 (I)], R ₁ = 0.0278, wR ₂ = 0.0747). In the case of nickel, two different geometric isomers are observed, depending on the chelate identity: trans-(DMSO)₂Ni(bpy)Cl₂ DMSO (3) (monoclinic, P21/c, a = 10.9149(8)Å, b = 12.1287(9)Å, c = 17.0044(13)Å, = 98.610(1)°, Z = 4,3519 reflections [I 2 (I)], R ₁ = 0.0209, wR ₂ = 0.0560) and cis-(DMSO)₂Ni(phen)Cl₂ (4) (monoclinic, P21/c, a = 8.404(2)Å, b = 14.051(4)Å, c = 16.710(4)Å, = 92.44(3)°, Z = 4, 3069 reflections [I 2 (I)], R ₁ = 0.0691, wR ₂ = 0.1782).