Melvyn Rowen Churchill

Structural considerations of terdentate ligands: crystal structures of 2,2′ : 6′,2″-terpyridine and 2,6-bis(pyrazol-1-yl)pyridine

The crystal structures of the terdentate ligands 2,2′ : 6′,2″-terpyridine (terpy) and 2,6-bis(pyrazol-1-yl)pyridine (bppy) were determined by single-crystal diffraction studies. The compound terpy crystallizes in the non-centrosymmetric orthorhombic space group P212121 with a= 3.947(1), b= 16.577(7) and c= 17.840(6)A; the structure was refined to R= 0.0745 for all 1087 independent data and R= 0.0470 for those 609 data with F > 6σ(F). The compound bppy crystallizes in the centrosymmetric orthorhombic space group Pnma with a= 11.929(3), b= 21.320(3) and c= 3.889(0)A; this structure was refined to R= 0.0409 for all 896 independent data and R= 0.0300 for those 723 reflections with F > 6σ(F). The structures of the free terpy and bppy ligands were compared directly with the structures of the co-ordinated terpy and bppy ligands in the [RuL(NO2)(PMe3)2][ClO4] complexes (L = terpy 1 or bppy 2) in order to determine if any ligand structural changes occur upon co-ordination to ruthenium. To act as terdentate ligands, it was observed that both terpy and bppy must adopt the cis,cis ligand configuration as opposed to the trans,trans configuration found in the solid state and as the equilibrium configuration in solution. Both terpy and bppy distort upon co-ordination to ruthenium. The greatest distortions for terpy occur primarily at the central pyridine ring. Large distortions were observed for bppy at both in the central pyridine ring and in the terminal pyrazole rings.

Crystal and molecular structure of tetramethylammonium carbidohexadecacarbonylhexaferrate(2–), [Me4N]2[Fe6(CO)16C], a hexanuclear iron cluster complex with an encapsulated six-co-ordinate carbon atom

The title compound crystallizes in the centrosymmetric orthorhombic space group Pnma, with a= 10·098(15), b= 18·788(20), c= 36·712(36)A, and Z= 8. The structure was solved by packing considerations and was refined to R 11·9% for the 1584 independent nonzero reflections. The asymmetric unit consists of two half-anions of [Fe6(CO)16C]2–(the remaining halves being generated by crystallographic mirror planes) and two [Me4N]+ cations. The [Fe6(CO)16C]2– anion has 13 terminal carbonyl ligands [two per iron atom, except for Fe(4) which bears three], and 3 ‘semi-bridging’ carbonyls. Nonbridged Fe–Fe bonds range from 2·646(10) to 2·743(10)A, bridged Fe–Fe bonds from 2·553(10) to 2·632(10)A. The encapsulated carbido-carbon atom is octahedrally co-ordinated to six iron atoms, with individual Fe–C distances from 1·805(38) to 1·968(38)A.

Synthesis and x-ray crystallographic characterization of (μ3-Bi)2Fe3(CO)9: A reformulation of Hieber's Bi2Fe5(CO)20

Abstract When [HFe(CO) 4 ] − is treated first with NaBiO 3 and then dilute H 2 SO 4 , a complex mixture of neutral metal carbonyl clusters results, some of which can be extracted into petroleum ether. Upon prolonged standing the extract yields a precipitate which has been characterized by X-ray crystallography as Bi 2 Fe 3 (CO) 9 . The complex Bi 2 Fe 3 (CO) 9 crystallizes in the centrosymmetric orthorhombic space group Cmcm ( D 2 h 17 ; No. 63) with a 10.616(2) A, b 13.458(3) A, c 11.347(3) A, V 1621.1(7) A 3 and Z = 4. Single-crystal X-ray diffraction data (Mo- K α , 2θ = 4.5–55.0°) were collected on a Syntex P2 1 four-circle diffractometer and the structure was refined to R F 5.4% and R W F 4.5% for all 1039 independent data ( R F 4.5% and R W F 4.5% for those 851 reflections with | F 0 | > 3.0σ(| F 0 |)). The molecule lies on a site of crystallographic C 2 v symmetry and is disordered. The individual molecules have a trigonal bipyramidal Bi 2 Fe 3 core with the bismuth atoms occupying the apical sites (BiFe 2.617(2)–2.643(2) A, FeFe 2.735(5)–2.757(5) A). Each iron atom is linked to three terminal carbonyl ligands and the molecule has approximate C 3 h symmetry. The nine peripheral oxygen atoms are ordered and define a tricapped trigonal prism. The equatorial iron atoms are disordered with the two Fe 3 triangles mutually displaced by approximately 30°; the disordered ensemble has approximate D 3 h symmetry.

Photoinduced formation of phosphido-bridged clusters derived from Ru3(CO)9(PPh2H)3. Crystal and molecular structure of Ru3(μ-H)(μ-PPh2)3(CO)7

Abstract The new complex Ru 3 (CO) 9 (PPh 2 H) 3 (I) was prepared by the direct thermal reaction of Ru 3 (CO) 12 with PPh 2 H and was spectroscopically characterized. Irradiation of I with λ ≥ 300 nm leads to the formation of Ru 2 (μ-PPh 2 ) 2 (CO) 6 (II) and three new phosphido-bridged complexes, Ru 3 (μ-H) 2 (μ-PPh 2 ) 2 (CO) 8 (III), Ru 3 (μ-H) 2 (μ-PPh 2 ) 2 (CO) 7 (PPh 2 H) (IV) and Ru 3 (μ-H)(μ-PPh 2 ) 3 (CO) 7 (V). These complexes have been characterized spectroscopically and Ru 3 (μ-H)(μ-PPh 2 ) 3 (CO) 7 by a complete single crystal X-ray structure determination. It crystallizes in the space group P 2 1 / n with a 20.256(3), b 22.418(6), c 20.433(5) A, β 112.64(2)°, V 8564(4) A 3 , and Z = 8. Diffraction data were collected on a Syntex P2 1 automated diffractometer using graphite-monochromatized Mo-K α radiation, and the structure was refined to R F 4.76% and R w F 5.25% for the 8,847 independent reflections with F 0 > 6σ(F 0 ). The structure consists of a triangular array of Ru atoms with seven terminal carbonyl ligands, three bridging diphenylphosphido ligands which bridge each of the RuRu bonds, and the hydride ligand which bridges one RuRu bond. Complex IV was also shown to give V upon photolysis and is thus an intermediate in the photoinduced formation of V from I.

Effect of carbenoid structure on the reactions of rhodium-stabilized carbenoids with cycloheptatriene

Rhodium prolinate catalyzed reactions of diazocarbonyls with cycloheptatriene are very dependent on the carbenoid structure and can result in either cyclopropanation, C–H insertion or a combined C–H insertion Cope rearrangement.

X-ray structural characterization of [Et4N+]3[BiFe4(CO)163−]

Abstract Sodium bismuthate has previously been reported to react with Fe(CO) 5 in methanolic KOH, producing the [BiFe 4 (CO) 16 3− ] anion. [Et 4 N + ] 3 [BiFe 4 (CO) 16 3− ] crystallizes in the centrosymmetric monoclinic space group P 2 1 / n with a 13.497(2), b 19.765(3), c 19.275(3) A, β 91.086(13)°, V 5141.0(15) A 3 , Z = 4. Diffraction data (2θ = 4.5–45.0°, using Mo- K α radiation) were collected with a Syntex P2 1 automated four-circle diffractometer and the structure was refined to R F 7.5% and R wF 6.1% for those 4306 reflections with | F o | > 3σ(| F o |). The [BiFe 4 (CO) 16 3− ] anion contains a central bismuth tetrahedrally surrounded by Fe(CO) 4 units, with an average Bi—Fe distance of 2.750(2) A. Each iron atom is in a trigonal-bipyramidal environment. The three Et 4 N + cations are all disordered.

Iridium-carbonyl clusters: VI. Mixed-metal clusters via metal-hydride coupling. Synthesis of CpMM′3(CO)11 (M = Mo, W; M′ = Co, Ir) and the crystal structure of CpMoIr3(CO)11

Abstract The reaction of CpM(CO) 3 H (M = Mo, W), with IrCl(CO) 2 ( p -toluidine) leads to the species CpMIr 3 (CO) 11 ; reaction of CpM(CO) 3 H with Co 4 (CO) 12 produces the known species CpMCo(CO) 11 in high yield. The newly-reported species CpMoIr 3 (CO) 11 has been subjected to an X-ray structural analysis. It crystallizes in the centrosymmetric orthorhombic space group Pbca (No. 61) with a 12.2830(15), b 13.5113(18), c 24.9418(30) A, V 4139.3(9) A 3 and Z = 8.Diffraction data were collected with a Syntex P2 1 automated diffractometer (Mo- K α radiation, 2θ 4.0–45.0°) and the structure was refined to R 5.4% for all 2421 data ( R 4.5% for those 2141 data above 3σ(¦ F 0 ¦)). CpMoIr 3 (CO) 11 is neither isomorphous nor isostructural with the known species CpWIr 3 (CO) 11 or CpMoCo 3 (CO) 11 . It differs by possessing three bridging carbonyl ligands which encircle one MoIr 2 face of the tetrahedral MoIr 3 cluster. The structure is completed by a Cp ligand on Mo and eight terminal carbonyl ligands (one on the molybdenum atom, three on the unique iridium atom and two each on the iridium atoms associated with the MoIr 2 (μ-CO) 3 moiety). The molecule has approximate C s symmetry.

Synthesis and characterization of the yttrium(III) and lutetium(III) complexes of 1,4,7-tris(carbamoylmethyl)-1,4,7-triazacyclononane (TCMT). Crystal structure of [Y(TCMT)(CF3SO3)2(H2O)](CF3SO3)

The 1,4,7-tris(carbamoylmethyl)-1,4,7-triazacyclononane (TCMT) ligand and its complexes with yttrium(III) and lutetium(III) have been prepared. [Y(TCMT)(CF3SO3)2(H2O)](CF3SO3) crystallizes in the centrosymmetric triclinic space group P1 (No. 2) with a = 10.3660(14), b = 11.7663(15), c = 13.3008(20) A, α = 72.079(10), β = 81.684(12), γ = 78.401(11)°, V = 1506.1(4) and Z = 2. The structure was refined to R = 5.64% for those 1758 reflections with |Fo| > 6σ(|Fo|). The nonacoordinate yttrium(III) ion has a bound water molecule, two bound triflate ions and a hexadentate TCMT ligand. The coordination geometry may be described as a 3:5:1 arrangement in which the C6N3 backbone occupies the ‘3’ sites and H2O the unique ‘1’ site, or alternatively as a capped square antiprism or as a distorted tricapped trigonal prism. The [Ln(TCMT)]3+ complexes dissociate completely in aqueous solution within 25 min at pH 6.0 and 37°C in the presence of Cu2+ as a trapping agent. Molecular mechanics calculations have been used to investigate the strain energy of the TCMT and 1,4,7-triazacyclononane-1,4,7-triacetate (NOTA) ligands in complexes that are 6-, 7- or 9-coordinate.

Silicone grease as a precursor to a pseudo crown ether ligand: crystal structure of [K+]3[K(Me2SiO)7+][InH(CH2CMe3)3–]4

The crystallization of K[InH(CH2CMe3)3] from heptane in the presence of silicone grease led to the formation of the title compound, in which one potassium cation is surrounded by a planar cyclo-(Me2SiO)7 ligand; K+⋯ O distances range from 2.86(3) to 2.99(4)A.

Structural studies on osmium carbonyl hydrides XXVI. Crystal structure of a complex with a 2-methylimidazolyl ligand bound to a triosmium cluster: (μ-H)Os3(CO)10[μ-3,4-η2-C3N2H2(2-CH3)] ☆

Abstract The compound (μ-H)Os3(CO)10[μ-3,4-η2-C3N2H2(2-CH3)] has been studied via a single-crystal X-ray diffraction study. It crystallizes in the centrosymmetric mono-clinic space group P21/n with a 9.568(3), b 17.663(5), c 12.063(2) A and β 97.72(2)°. All non-hydrogen atoms were located and the structure was refined to RF 5.5% for all 1894 data and RF 3.7% for those 1511 data with ¦F0¦ > 3σ(¦F0¦). Unlike the corresponding imidazolyl complex, this 2-methylimidazolyl complex is ordered in the crystalline state. The two non-bridged OsOs bond lengths are Os(1)Os(3) 2.884(1) and Os(2)Os(3) 2.892(1) A, while the di-bridged distance is Os(1)Os(2) 2.957(1) A. The 2-methylimidazolyl ligand is bonded to the triosmium cluster via the linkages Os(1)N(1) 2.153(16) A and Os(2)C(1) 2.089(18) A.