M.C. Puerta

Unusual reverse face-to-face stacking in propylene linked pyrazole system: perspective of organic materials

Flexible dimers 1, 2, and 3 of “pyrazole” derivatives linked with propylene spacer are synthesized and conformational stability in solid, solution, and gaseous states is studied through single crystal X-ray diffraction, 2D NOESY ,and DFT, respectively. The folded conformation of compound 2 is stable in all three states and X-ray diffraction evince that molecule is intramolecularly stacked in reverse face-to-face manner. TEM image of compound 2 exhibits rigid hollow nanospikes with high tendency to form agglomerates.

Displacement of tetrahydrofuran ligands by tripodal phosphines. Crystal structure of [MoCl3{N(CH2CH2PPh2)3}]·C4H8O

The complexes [MoCl3{P(CH2CH2PPh2)3}]·thf and [MoCl3{N(CH2CH2PPh2)3}]·thf (thf = tetrahydrofuran) have been prepared from [MoCl3(thf)3] by ligand replacement reaction of thf. An X-ray crystal structure investigation of [MoCl3{N(CH2CH2PPh2)3}]·thf shows a distorted-octahedral structure with a meridional arrangement of the three chlorine ligands. The amine acts as tridentate ligand with a pendant PPh2 group.

Dinitrogen and related compounds of molybdenum with the tripodal phosphines N(CH2CH2PPh2)3 or P(CH2CH2PPh2)3 as coligands

The reduction of [MoCl3{N(CH2CH2PPh2)3}] with a sodium dispersion in tetrahydrofuran (thf) under a dinitrogen atmosphere yields the unstable complex cis-[Mo(N2)2{N(CH2CH2PPh2)3}], which decomposes in a few days even in solution under dinitrogen. Studies of the chemical reactivity of this compound towards carbon monoxide, PMe3, Mel and CF3CO2H have been carried out and the complexes [Mo(CO)3L], [Mo(PMe3)3L], [Mol2L] and [Mo(CF3CO2)2L][L = N(CH2CH2PPh2)3] have been isolated and identified. The reduction of the analogous complex [MoCl3{P(CH2CH2PPh2)3}] gives unstable trans-[Mo(N2)2{P(CH2CH2PPh2)3}]. The ligand-substitution reaction of cis-[Mo(N2)2(PMe3)4] with N(CH2CH2PPh2)3 yields the complex cis-[Mo(N2)(PMe3){N(CH2CH2PPh2)3}].

Synthesis and reactivity of [MCl2(CNBut)3(PMe3)2] (M = Mo or W): preparation of [MCl(CNBut)4(PMe3)2]Cl and [M(SnCl3)(CNBut)3(PMe3)3](SnCl3) derivatives. The crystal structure of [MoCl(CNBut)4(PMe3)2]Cl·2Me2CO

Abstract The reaction of the sixteen-electron paramagnetic complex [MCl 2 (PMe 3 ) 4 ](M = Mo or W) with CNBu t gives the eighteen-electron diamagnetic seven-coordinate complex [MoCl 2 (CNBu t ) 3 (PMe 3 ) 2 ] ( 1 ) or [WCl 2 (CNBu t ) 3 (PMe 3 ) 2 ] ( 2 ). These complexes react with additional CNBu t to give the complexes [MCl(CNBu t ) 4 -(PMe 3 ) 2 ]Cl (M = Mo ( 3 ) or W ( 4 )). An X-ray diffraction study of 3 shows it to have a capped trigonal prismatic structure in the solid state. The reaction of [MCl 2 -(CNBu t ) 3 (PMe 3 ) 2 ] with anhydrous SnCl 2 yields the complexes [M(SnCl 3 )-(CNBu t ) 3 (PMe 3 ) 3 ](SnCl 3 ) (M = Mo ( 5 ) or W ( 6 )), which have been studied by 119 Sn NMR spectroscopy. A new route to the complex trans -[MoCl 2 (PMe 3 ) 4 ] from MoCl 5 has also been developed.

Dinitrogen complexes of chromium(III) with chelating agents

SummaryTwo new dinitrogen complexes of CrIII with EDTA and CDTA have been prepared from reaction of [Cr(Y-H)H2O] (Y = EDTA, CDTA) with sodium azide in aqueous solution. Both complexes exhibit characteristic bands at 2070 cm−1 in the i.r. spectra corresponding to ν(N2). The 10 Dq and B parameters were calculated from the u.v. visible spectra.

Reactivity of seven-coordinate molybdenum(II) and tungsten(II) isocyanide complexes: The crystal structure of [MoCl(CNBut4(PMe3)2]Cl

Abstract The seven-coordinate isocyanide complexes [MCl2(CNBut)3(PMe3)2] (M = Mo or W), react with additional CNBut yielding the derivatives [MCl(CNBut)4(PMe3)2]Cl. The crystal structure of the [MoCl(CNBut)4(PMe3)2]Cl complex shows an almost perfect two- fold symmetry for the cation [MoCl(CNBut)4(PMe3)2+ along the MoCl bond and two different possible orientations for the t-butyl groups. The reaction of [MCl2(CNBut)3 (PMe3)2 (M = Mo or W) with anhydrous SnCl2 yields complexes containing the SnCl3− ligand, derived from the insertion of SnCl2 into the metal-halide bond.

Thermal decomposition of dinitrogen complexes of Cr(III)

Abstract The thermal behaviour of two dinitrogen complexes of chromium with EDTA and CDTA have been studied using DTA and TG. IR spectroscopy is used for the characterization of intermediate products. The loss of dinitrogen occurs at 240°C in both cases.