Pamela A. Wexler

95Mo NMR investigation on cationic [C5H5Mo(CO)2L2]BF4 complexes (L = group 15 donor ligands ☆

Abstract Photochemically-initiated oxidative fission of the MoMo bond in [C5H5Mo(CO)3]2 by the ferricenium salt [(C5H5)2Fe]BF4 in the presence of four equivalents of L affords a good yield of [C5H5Mo(CO)2L2]BF4 (L = group 15 donor ligands). 95Mo NMR data are reported and discussed together with the NMR and IR data of new complexes. Decomposition of the title cations in polar solvents affords low yields of the corresponding [C5H5MO(CO)3L]BF4 complexes. The X-ray crystal structure of [C5H5Mo (CO)3{P(C6H5)3}]BF4 is reported. The cation has the CpML4 piano-stool geometry.

Paramagnetic organometallics: preparation, structural, and redox chemistry of tantalum(II) η6-arene complexes

The reduction of (η6-C6R6)Ta(OR′)2Cl [(1) R = Et; (2) R = Me; OR′= 2,6-diisopropylphenoxide] with excess Na/Hg provides the first well characterised TaII organometallics, viz. the monomeric compounds (η6-C6R6)Ta(OR′)2[(3) R = Et; (4) R = Me]; the X-ray structure of (η6-C6Et6)Ta (O-2,6-Pri2C6H3)2(3), reveals some unusual distortions in the co-ordinated arene ligand.

Crystal and molecular structure of [SnLCl3]]. The single-crystal electron paramagnetic resonance spectra of [MoE(L)Cl2] and [MoO(L)(NCS)2] diluted in [SnLCl3] [E=O or S;L=tris(3,5-dimethylpyrazolyl)hydroborate]

The crystal structure of [SnLCl3] has been determined and shown to consist of discrete distorted fac-octahedral molecules [L = tris(3,5-dimethylpyrazolyl)hydroborate]. The single-crystal EPR spectra, at room temperature and Q-band frequencies, of [MoE(L)Cl2] and [MoO(L)(NCS)2], E = O or S, diluted in the structurally similar [SnLCl3] have been recorded. The data from the different possible diluent sites in [SnLCl3] are consistent with exact, or nearly exact, monoclinic EPR symmetry for each of the molybdenum compounds which involves a rotation of the g and A tensors about an axis perpendicular to the mirror plane in each molecule. The angles of rotation are in the range 30–38° and are in good agreement with those obtained via simulation of the frozen-solution X-band EPR spectra of the compounds. The relationships between the g and A tensors, the molecular geometries, and the electronic structures are discussed.

Structure of an enantiomerically pure tetrahydropyranyl ether

S)-Methyl 2-phenyl-2-((2S)-tetrahydro- 2(2H)-pyranyloxy)acetate, C14H1804, Mr=250.29, orthorhombic, P21212~, a = 7.850 (1), b = 8.211 (1), c=21.123(3) A, V=1361.5 (3) A 3, Z=4, Dx= 1.22 gcm -3, Mo KeG A = 0.71073 A, /x = 0.8 cm- 1, F(000) = 536, T = 296 K, R = 0.039 for 973 unique reflections with Fo2> 3tr(Fo2). In this diastereomer the anomeric alkoxy substituent is axially oriented. The absolute stereochemistry at the anomeric carbon is assigned as S based upon the known stereo- chemistry of the mandelate ester.