TY - JOUR

T1 - Hemilability of phosphine-thioether ligands coordinated to trinuclear Mo3S4 cluster and its effect on hydrogenation catalysis

AU - Gushchin, Artem L.

AU - Shmelev, Nikita Y.

AU - Malysheva, Svetlana F.

AU - Artem'ev, Alexander V.

AU - Belogorlova, Nataliya A.

AU - Abramov, Pavel A.

AU - Kompan'kov, Nikolay B.

AU - Manoury, Eric

AU - Poli, Rinaldo

AU - Sheven, Dmitriy G.

AU - Llusar, Rosa

AU - Sokolov, Maxim N.

N1 - Publisher Copyright: © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.

PY - 2018/11/7

Y1 - 2018/11/7

N2 - Ligand-exchange reactions of [Mo3S4(tu)8(H2O)]Cl4·4H2O (tu = thiourea) with (PhCH2CH2)2PCH2CH2SR ligands, where R = Ph (PS1), pentyl (PS2) or Pr (PS3), afford new complexes isolated as [Mo3S4Cl3(PS1)3]PF6 ([1]PF6), [Mo3S4Cl3(PS2)3]PF6 ([2]PF6) and [Mo3S4Cl3(PS3)3]PF6 ([3]PF6) salts in 30-50% yields as the major reaction products. The crystal structures of [1]PF6 and [2]PF6 were determined by X-ray diffraction (XRD) analysis. Each of the three phosphine-thioether ligands is coordinated in a bidentate chelating mode to a different molybdenum atom of the Mo3S4 trinuclear cluster; herein, all the phosphorus atoms of the phosphino-thioether ligand are located trans to the capping sulfur (μ3-S). A second product that forms in the reaction of [Mo3S4(tu)8(H2O)]Cl4·4H2O with PS1 corresponds to the neutral [Mo3S4Cl4(PS1)2(PS1*)] complex. Its XRD analysis reveals both bidentate (PS1) and monodentate (PS1*) coordinating modes of the same ligand. In the latter mode the phosphine-thioether is coordinated to a Mo atom only via the P atom. All compounds were characterized using 1H and 31P{1H} NMR spectroscopy, electrospray-ionization (ESI) mass spectrometry and cyclic voltammetry (CV). Reactions of [1]PF6, [2]PF6 and [3]PF6 with an excess of Bu4NCl in CD2Cl2 were followed by 31P{1H} NMR spectroscopy. The spectra indicate equilibrium between cationic [Mo3S4Cl3(PSn)3]+ and neutral [Mo3S4Cl4(PSn)2(PSn*)] (n = 1, 2) species. The equilibrium constants were determined as 2.5 ± 0.2 × 103 M−1, 43 ± 2 M−1 and 30 ± 2 M−1 (at 25 °C) for [1]PF6, [2]PF6 and [3]PF6, respectively, indicating quantitative differences in the hemilabile behaviors of the phosphino-thioether ligands, depending on the substituent at the sulfur. Clusters [1]PF6, [2]PF6 and [3]PF6 were tested as catalysts in the reduction of nitrobenzene to aniline with Ph2SiH2 under mild conditions. Significant differences in the catalytic activities were observed, which can be attributed to different hemilabile behaviors of the PS1 and PS2/PS3 ligands.

AB - Ligand-exchange reactions of [Mo3S4(tu)8(H2O)]Cl4·4H2O (tu = thiourea) with (PhCH2CH2)2PCH2CH2SR ligands, where R = Ph (PS1), pentyl (PS2) or Pr (PS3), afford new complexes isolated as [Mo3S4Cl3(PS1)3]PF6 ([1]PF6), [Mo3S4Cl3(PS2)3]PF6 ([2]PF6) and [Mo3S4Cl3(PS3)3]PF6 ([3]PF6) salts in 30-50% yields as the major reaction products. The crystal structures of [1]PF6 and [2]PF6 were determined by X-ray diffraction (XRD) analysis. Each of the three phosphine-thioether ligands is coordinated in a bidentate chelating mode to a different molybdenum atom of the Mo3S4 trinuclear cluster; herein, all the phosphorus atoms of the phosphino-thioether ligand are located trans to the capping sulfur (μ3-S). A second product that forms in the reaction of [Mo3S4(tu)8(H2O)]Cl4·4H2O with PS1 corresponds to the neutral [Mo3S4Cl4(PS1)2(PS1*)] complex. Its XRD analysis reveals both bidentate (PS1) and monodentate (PS1*) coordinating modes of the same ligand. In the latter mode the phosphine-thioether is coordinated to a Mo atom only via the P atom. All compounds were characterized using 1H and 31P{1H} NMR spectroscopy, electrospray-ionization (ESI) mass spectrometry and cyclic voltammetry (CV). Reactions of [1]PF6, [2]PF6 and [3]PF6 with an excess of Bu4NCl in CD2Cl2 were followed by 31P{1H} NMR spectroscopy. The spectra indicate equilibrium between cationic [Mo3S4Cl3(PSn)3]+ and neutral [Mo3S4Cl4(PSn)2(PSn*)] (n = 1, 2) species. The equilibrium constants were determined as 2.5 ± 0.2 × 103 M−1, 43 ± 2 M−1 and 30 ± 2 M−1 (at 25 °C) for [1]PF6, [2]PF6 and [3]PF6, respectively, indicating quantitative differences in the hemilabile behaviors of the phosphino-thioether ligands, depending on the substituent at the sulfur. Clusters [1]PF6, [2]PF6 and [3]PF6 were tested as catalysts in the reduction of nitrobenzene to aniline with Ph2SiH2 under mild conditions. Significant differences in the catalytic activities were observed, which can be attributed to different hemilabile behaviors of the PS1 and PS2/PS3 ligands.

KW - TRIRUTHENIUM CARBONYL-COMPLEXES

KW - N-HETEROCYCLIC CARBENES

KW - CUBANE-TYPE CLUSTERS

KW - PHP(C6H4-SH-2)(2) PHPS(2)H(2)

KW - AQUEOUS SPECIATION

KW - ANCILLARY LIGANDS

KW - CRYSTAL-STRUCTURE

KW - METAL-COMPLEXES

KW - MOLYBDENUM

KW - SUBSTITUTION

UR - http://www.scopus.com/inward/record.url?scp=85055528726&partnerID=8YFLogxK

U2 - 10.1039/c8nj03720e

DO - 10.1039/c8nj03720e

M3 - Article

AN - SCOPUS:85055528726

VL - 42

SP - 17708

EP - 17717

JO - New Journal of Chemistry

JF - New Journal of Chemistry

SN - 1144-0546

IS - 21

ER -