Schwingungsspektren und Kraftkonstanten des Tetraselenomolybdats(VI) und des Tetraselenowolframats(VI). Raman-Spektren von (NH4)2MoO2S2 und (NH4)2WO2S2

Intermediate Species Revealed during Sulfidation of Bimetallic Hydrotreating Catalyst: A Multivariate Analysis of Combined Time-Resolved Spectroscopies

“…The defined bands at 451 and 476 cm –1 could be assigned to stretching vibrational modes of the Mo–S (2−) bond in bridging and terminal positions, respectively. Indeed hexavalent molybdenum oxysulfidic species, (MoO x S 4– x ) 2– displays single line at ∼ 473 cm –1 for x = 2 or 3, , whereas stretching vibrations of bridging sulfido ligands are encountered between 420 and 460 cm –1 as reported in Table S1. Finally taking into account the complete lack of lines in the 500–600 cm –1 range for the spectrum of Comp.1 characteristic of the oxidic precursors, we propose to attribute the line at 540 cm –1 to the stretching mode of the S–S disulfido bridge as previously ascribed by Payen et al…”

“…The spectral range 420–480 cm –1 allows the unambiguous identification of vibrational modes involving sulfur since no overlap with Mo-O vibrations is expected. The lines can be assigned to the stretching vibration mode of bridging Mo V –μ 2 S–Mo V bonds as for (n-Bu 4 N) 2 (Mo V 2 O 2 S 2 (S 2 ) 2 ) and Mo IV -μ 3 S-Mo IV bonds as for (NH 4 ) 2 (Mo IV 3 S 13 ]·H 2 O or to the one of the Mo–S t bonds (here S t stands for a terminal sulfido ligand) like that encountered for the Raman spectrum of the (Mo VI O 4– x S x ) 2– anion. , …”

“…The lines can be assigned to the stretching vibration mode of bridging Mo V −μ 2 S−Mo V bonds as for (n-Bu 4 N) 2 (Mo V 2 O 2 S 2 (S 2 ) 2 ) 52 and Mo IV -μ 3 S-Mo IV bonds as for (NH 4 ) 2 (Mo IV 3 S 13 ]•H 2 O 53 or to the one of the Mo−S t bonds (here S t stands for a terminal sulfido ligand) like that encountered for the Raman spectrum of the (Mo VI O 4−x S x ) 2− anion. 54,55 In the 500−550 cm −1 region, the broad lines are generally associated to the stretching mode of bridged disulfide (S 2 2−…”

Synthesis of WS42– Intercalated NiZnAl LDHs as Effective Adsorbents to Remove Copper Ions from Water

“…Their spectra are shown in Figure . For ATT, an intense band at 481 cm –1 and a weak band at 455 cm –1 are, respectively, assigned to the symmetric and asymmetric stretching vibrations of W–S in WS 4 2– . Another weak band at 181 cm –1 is assigned to the bending vibration of S–W–S in WS 4 2– .…”

Vibrational spectra of intra- and inter-metal and semimetal bonds

“…These findings, however, should be contrasted with the report that the ¡¡(CO) frequencies are nearly identical for the series Cl3MCo(CO)4 (M = Si, Ge, Sn), though normal coordinate calculations show that the M-Co stretching force constant decreases in value as M changes from silicon to tin. 45 The Sn-M interaction is also said to increase when R changes from methyl to phenyl for R3SnMn(CO)5, R3SnMo(CO)3CsFl5, and R3- Sn-Pt 200 (ir) 61 213 (ir) 206 and Cl3GeCo(CO)4, the y(Sn-Co) mode of Cl3SnCo(CO)4 is fairly pure owing to the relatively heavy mass of the tin atom. 45 Still, heavy ligands such as chlorine and C6H5 are expected to couple to some extent with the y(Sn-M) mode, and this coupling cannot be ignored when relating shifts of KSn-M) frequencies to the relative strength of Sn-M bonds.…”