Synthesis, characterization and properties of Mo6S8(4-tert-butylpyridine)6 and related M6S8L6 cluster complexes (M = Mo, W)

Abstract

Octahedral molybdenum chalcogenide clusters are the building blocks of the well-known Chevrel phases. Although the synthesis of molecular Mo 6 S 8 L 6 (L = PEt 3 and pyridine) clusters has been previously reported, a high yield and larger scale synthetic procedure is needed to produce soluble Mo 6 S 8 L 6 (L = Lewis base ligand) clusters, so that they can be used as precursors for the construction of novel network structures. Using the previously developed W 6 S 8 (4tert-butylpyridine) 6 synthesis as a starting point, a facile, high yield (70%) synthesis of Mo 6 S 8 (4-tert-butylpyridine) 6 from (Bu 4 N) 2 Mo 6 Cl 8 Cl 6 was developed. This general sulfidation reaction scheme can be extended to the direct preparation of many M 6 S 8 L 6 (M = W, Mo; L = Lewis base ligand) complexes. Three Mo 6 S 8 L 6 complexes (L = PEt 3 , methylamine, 4,4Ј-bipyridine) were also prepared via ligand exchange reactions with Mo 6 S 8 (4-tert-butylpyridine) 6 . The above Mo 6 S 8 L 6 complexes were characterized and their reactivity was compared with their tungsten counterparts. Crystal structures were found for Mo 6 S 8 (4-tert-butylpyridine) 6 , Mo 6 S 8 (4,4Ј-bipyridine) 6 , and Mo 6 S 8 (methylamine) 6 .

Neutral Mo6Q8-clusters with terminal phosphane ligands – a route to water-soluble molecular units of Chevrel phases

“…20,21 Other methods of preparation of molybdenum chalcogenide clusters, mostly {Mo 6 S 8 }-based clusters, with phosphane (PEt 3 ) or other organic ligands (4- tert -butylpyridine, morpholine, etc. ) are presented in ref. 22 and 23.…”

“…). 22–24 Furthermore, [{Mo 6 S 8 }(4- t BuPy) 6 ] obtained using method (ii) was proved to be a useful parent compound for the synthesis of cluster complexes with other organic ligands (PEt 3 , 4,4′-bipyridyl (4,4′-bipy) and CH 3 NH 2 ). 23…”

“…Analysing the literature, only two synthetic methods can be singled out: (i) reduction of the triangular chalcogenide cluster Mo 3 Q 7 Cl 4 with metallic magnesium in tetrahydrofuran magnesium in the presence of PEt 3 20,21 and (ii) substitution of m 3 -bridging ligands in octahedral molybdenum halide complexes by the reaction with Q 2À in the presence of a pro-ligand, such as phosphanes (PEt 3 and PPh 3 ), or other organic ligands (4-tert-butylpyridine ((4-t BuPy)), morpholine, etc.). [22][23][24] Furthermore, [{Mo 6 S 8 }(4-t BuPy) 6 ] obtained using method (ii) was proved to be a useful parent compound for the synthesis of cluster complexes with other organic ligands (PEt 3 , 4,4 0 -bipyridyl (4,4 0 -bipy) and CH 3 NH 2 ). 23 Thus, herein we present the preparation and characterisation of two new chalcogenide molybdenum cluster compounds with (2-carboxyethyl)diphenylphosphane ligands [{Mo 6 Q 8 }(Ph 2 PC 2 H 4 COOH) 6 ] (Q = S (1), Se (2)) using the modified method (ii).…”

Apical Cyanide Ligand Substitution in Heterometallic Clusters [Re3Mo3Q8(CN)6]n– (Q = S, Se)

“…The average M–N distances are slightly longer than the typical Re–N distances found in the octahedral rhenium clusters with the terminal TBP or pyridine ligands. [4h] They are close to the Mo–N distances found in the compounds [Mo 6 S 8 (py) 6 ] and [Mo 6 S 8 (TBP) 6 ] . Presence of the voluminous tert ‐butyl group in the aromatic rings prevents the formation of π–π stacking between the terminal ligands of the nearby clusters.…”

Quantum Soldering of Individual Quantum Dots

“…The compound Co 6 Se 8 (PEt 3 ) 6 is part of a large and varied family of metal chalcogenide molecular clusters that includes Chevrel phase analogues such as Cr 6 Te 8 (PEt 3 ) 6 ,30 Mo 6 S 8 (PEt 3 ) 6 ,31, 32 and W 6 S 8 (PCy 3 ) 6 ,4, 33 and larger compounds that contain tens to hundreds of metal atoms 34. We anticipate that our approach will provide a route to integrating clusters with tunable optical, electronic, and magnetic properties into electrical circuits and devices.…”