Synthesis of four different antimony(III) O,O′-dialkyldithiophosphates: Characterization by 31P CP/MAS NMR, single-crystal X-ray diffraction, and adsorption at a stibnite surface (Sb2S3)
Graphical abstract
Highlights
► Crystal structure determination of [Sb{S2P(O-cyclo-C6H11)2}3]·1/3 C2H5OH. ► 31P CP/MAS NMR chemical shift anisotropy parameters for [Sb{(S2P(OR)2}3] complexes are determined. ► 31P CP/MAS NMR data on dithiophosphate ligands surface adsorbed on synthetic stibnite suggest a bridging coordination.
Introduction
Antimony and its compounds have many important applications, e.g., in alloys, in batteries, as flame-retardants, semiconductors, and pigments [1], [2], [3], [4], [5], [6], [7], [8], [9]. Antimony trisulfide (Sb2S3) has found use, e.g., in various optical and photosensitive applications, for radiolabeling, and as a lubricant [1], [2], [3], [4], [5], [6], [7], [8], [9]. The principal source of antimony is the natural mineral stibnite, Sb2S3. In the froth flotation of sulfide minerals, ionic O,O′-dialkyldithiophosphates (DTP) are frequently used reagent collectors. One of the important questions in flotation theory is connected with the fixation modes of ionic dithioreagent collectors (such as dialkyldithiophosphates, alkyldithiocarbonates (i.e., xanthates), and dialkyldithiocarbamates) on the surfaces of sulfide minerals. Previously, using both liquid and solid-state 31P NMR techniques, we have established principally different fixation modes of DTP ions on the surface of both synthetic sphalerite (ZnS) [10] and galena (PbS) [11]. The bridging coordination of DTP groups to two neighboring zinc atoms was suggested in the case of surface zinc(II) complexes on a ZnS surface [10], while there is mainly terminal S,S′-chelating coordination of DTP ions to one lead atom on a PbS surface [11]. To get an efficient flotation of Sb2S3, it is meaningful to understand the interaction between mineral surface and ionic dialkyldithiophosphate collectors.
In this study, we have characterized four different potassium O,O′-dialkyldithiophosphates adsorbed on the surface of synthetically prepared Sb2S3. It is known that Sb(III) is starting to oxidize to Sb(V) at pH above 4 [9]. In order to avoid oxidation, the adsorption experiments were performed at pH 3. 31P CP/MAS NMR was used to study the coordination of DTP groups to the mineral surface. For comparison, Sb(DTP)3 complexes with the same ligands were synthesized and 31P and 13C CP/MAS NMR measurements were taken. Both 31P chemical shifts and chemical shift anisotropy (CSA) were used to characterize the surface coordination.
Additionally, the crystal and molecular structure of tris(O,O′-di-cyclo-hexyldithiophosphato-S,S′)antimony(III), which is solvated with ethanol, has been determined using the single-crystal X-ray diffraction technique.
Section snippets
Synthesis of Sb2S3
Antimony trisulfide, Sb2S3, was synthesized in basically the same way as is previously reported [2]. An excess of thioacetamide was added to a 0.1 M solution of SbCl3 in absolute ethanol. The solution was stirred until the color changed from yellow to red. The mixture was left for 24 h before the precipitate was filtered and washed with ethanol. The red Sb2S3 was dried in vacuum at 100 °C until it transformed into the stable black form. The identity of the sample was confirmed by XRD.
Preparation of surface complexes
Surface
Structural description of [Sb{S2P(O-cyclo-C6H11)2}3]·1/3 C2H5OH (III)
Table 1 summarizes selected crystal data for solvated compound III. The unit cell of the compound comprises eighteen molecules of tris(O,O′-di-cyclo-hexyldithiophosphato-S,S′)antimony(III) and six ethanol molecules, [Sb{S2P(O-cyclo-C6H11)2}3]·1/3 C2H5OH.
The central antimony atom exhibits a sixfold coordination with three dithiophosphate groups acting as S,S′-bidentate-chelating ligands (see Fig. 2). Therefore, the coordination polyhedron [SbS6] can be approximated by a distorted octahedron,
Summary and conclusions
31P CP/MAS NMR data show that even if the isotropic chemical shifts of the DTP groups adsorbed at the Sb2S3 surface are almost identical to the chemical shifts of the corresponding Sb(DTP)3 complexes, the chemical shift anisotropy tensors are completely different for these two types of species. The tensors are more spherical for the 31P nuclei in the chemisorbed complexes and more prolate for the more crystalline Sb(DTP)3 complexes, indicating that the SPS bite angle increases when the DTP
Supplementary material
CCDC 833600 contains the supplementary crystallographic data for complex III. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336 033; or e-mail: [email protected].
Acknowledgments
We wish to thank CHEMINOVA AGRO A/S for kindly supplying the potassium dialkyldithiophosphate salts. Part of the study was financed by Agricola Research Centre Multicomponent Mineral Systems (ARC-MMS), through the Strategic Mining Research Program, co-funded by the Swedish mining industry and the Swedish Governmental Agency for Innovation Systems (Vinnova), and Centre for Advanced Mining and Metallurgy (CAMM), financed by strategic funds from the Swedish Government.
References (47)
- et al.
Mater. Res. Bull.
(2003) - et al.
Solid State Commun.
(1978) - et al.
Appl. Radiat. Isotopes
(2003) - et al.
Mater. Chem. Phys.
(2000) - et al.
Wear
(2006) - et al.
Inorg. Chim. Acta
(2001) - et al.
J. Coll. Interf. Sci.
(2008) - et al.
Inorg. Chim. Acta
(1983) - et al.
J. Magn. Reson.
(2003) - et al.
J. Magn. Reson.
(1998)
Solid State Nucl. Mag.
Inorg. Chim. Acta
Inorg. Chim. Acta
J. Magn. Reson.
Inorg. Chim. Acta
Polyhedron
Structure-Property Relations in Nonferrous Metals
D: Appl. Phys.
J. Mater. Chem.
Trans. Instn. Min. Metall. (Sect. C: Miner. Process. Extr. Metall.)
Zhur. Obshch. Khim.
Lubric. Eng.
J. Chem. Phys.
Cited by (7)
A novel surfactant O,O'-bis(2-butoxyethyl) ammonium dithiophosphate: Synthesis, selective flotation and adsorption mechanism towards galena
2022, Minerals EngineeringCitation Excerpt :Dithiophosphorus acid is an organophosphorus compound and can chelate with Cu, Pb, Zn, Pt, Au, Ag, Co and Ni to form metal complexes. They are commonly used as lubricant additives (Huq et al., 2007; Mosey and Woo, 2006; Rodina et al., 2011; Sánchez et al., 2004), agricultural pesticides or fertilizer (Huang et al., 2019c; Kabra et al., 2009), metal extractants or corrosion inhibitors (Alam et al., 1997; Alimarin et al., 1989; Larsson et al., 2012; Sole et al., 1995) and flotation collectors (Fan et al., 2019; Kloppers et al., 2016; McFadzean et al., 2012; Tijsseling et al., 2019; Wiese et al., 2005). As flotation collectors, the most widely used dithiophosphorus acid compounds are dithiophosphate (DTP) and dithiophosphinate (DTPI) because of their high selectivity for galena and sphalerite/pyrite separation (McFadzean et al., 2013; Pecina-Treviño et al., 2003; Tercero et al., 2019; Zhong et al., 2015).
Interaction mechanism of lead ions with stibnite surfaces and enhancement of xanthate adsorption
2021, Journal of Molecular LiquidsCitation Excerpt :Stibnite is often associated with native gold, scheelite, pyrite, and arsenopyrite [6–9]. Stibnite is concentrated and separated from gangue minerals by flotation, using a variety of activators and collectors [10–13]. The use of a metal ion as an activator in the flotation of valuable minerals has been widely reported.
Indirect influence of alkyl substituent on sigma-hole interactions: The case study of antimony(III) diphenyldithiophosphates with covalent Sb-S and non-covalent Sb⋯S pnictogen bonds
2019, PolyhedronCitation Excerpt :In this structure all the three dicyclohexyldithiophosphate ligands reveal a pronounced anisobidentate mode of coordination to the antimony(III). For each of the dithiophosphate group one of the Sb–S bonds is essentially shorter as compared with the other one [18]. In a similar manner to the above example, aromatic complex Sb{S2P(OC6H4Me-m)2}3 adopts a distorted octahedral arrangement of sulfur atoms around antimony(III) center due to anisobidentate binding [19].
A fixation mode of gold from solutions using heterogeneous reaction of cadmium dicyclohexyl dithiophosphate with H[AuCl<inf>4</inf>]. Structural and (<sup>13</sup>C, <sup>31</sup>P) CP/MAS NMR studies and thermal behaviour of crystalline polymeric gold(I) dicyclohexyl dithiophosphate and bis(dicyclohexylthiophosphoryl) disulphide
2013, Journal of Molecular StructureCitation Excerpt :This structural diversity is defined by the possibilities of dithiophosphate ligands to play various structural functions, (i.e., unidentate, terminal chelating, bridging or combined coordination). Previously, different dithiophosphate compounds comprising cyclo-hexyl substituents have been characterised using X-ray diffraction (XRD) and multinuclear (13C, 31P, 113Cd, 195Pt) CP/MAS NMR: ammonium [5], potassium [6], nickel(II) [7–10], chromium(III) [11], platinum(II) [12,13], zinc(II) [1], cadmium(II) [14,15], lead(II) [16,17], thallium(I) [18] and antimony (III) [3]. ( Di-cyclo-pentyl dithiophosphate nickel(II) and mercury(II) complexes have been also described [19,20].)
Arsenic(III) complexes of substituted diphenyldithiophosphate: synthesis, characterization, single crystal X-ray, DFT, and Hirshfeld surface analysis
2020, Journal of Coordination ChemistryApplications of nuclear shielding
2014, Nuclear Magnetic Resonance