Molybdenum-95 NMR measurements of dioxomolybdenum(VI) complexes. 3. Inverse halogen dependence of molybdenum chemical shift of [MoO2]2+ complexes

Molybdenum-95 NMR study of mononuclear oxomolybdenum(IV) complexes

“…The relatively shielded resonances of the oxo-Mo(IV) complexes containing NCS" and NCO" ligands further corroborate the inverse halogen dependence because in other systems displaying this dependence the NCS" complexes are shielded compared to the analogous halo complexes. 14 The shielding of 95Mo by NCS" and NCO" in the present complexes is, however, substantially greater than that previously observed (ca. 300 vs. 90 ppm).…”

Oxo sulfido ligand substitution in dimolybdate ([Mo2O7]2-): reaction sequence and characterization of the final product, [MoS3(OSiMe3)]-

“…49 Others have found that reaction of certain dioxomolybdenum(VI) complexes with (Me3Si)2S afforded paramagnetic species and no new 95Mo signals. 50 Apparent reduction is also found in the = 7 system. Here spectropho-tometric yields of [0,3], measured at 403 and 534 nm and based on the extinction coefficients of the isolated Ph4P+ salt, are 82-89%.…”

Synthesis and Characterization of MO[OSi(OtBu)3]4 and MO2[OSi(OtBu)3]2 (M = Mo, W): Models for Isolated Oxo-Molybdenum and -Tungsten Sites on Silica and Precursors to Molybdena− and Tungsta−Silica Materials

“…The compound 3a exhibits a singlet at −156 ppm (ω 1/2 = 173 Hz) in its 95 Mo NMR spectrum. Significant chemical shift differences have been observed for complexes of the MoO 2 2+ group upon changing the donor atoms of the additional ligands (δ −219 to +630). , Negative chemical shifts occur for MoO 2 2+ species ligated exclusively by O atoms . The chemical shift of 3a is at relatively high field compared to those assigned to dioxo-molybdenum complexes containing siloxide ligands, such as MoO 2 [( c -C 6 H 11 ) 7 (Si 7 O 11 )(OTMS)] (δ −70.6, ω 1/2 = 220 Hz) …”