Systematic Approach for the Construction of Niobium and Tantalum Sulfide Clusters

Abstract

Treatment of the imido complexes [MCl3(NR)py2] (R = (t)Bu, 2,6-Me2C6H3; M = Nb 1, 3; Ta 2, 4) (Xyl = 2,6-Me2C6H3) with (Me3Si)2S in a 1:1 ratio afforded the new cube-type sulfide clusters [MCl(NR)py(μ3-S)]4 (R = (t)Bu, 2,6-Me2C6H3; M = Nb 5, 7; Ta 6, 8) with loss of Me3SiCl. Reactions of 5 and 6 with cyclopentadienyllithium in 1:4 ratio resulted in the rupture of the coordinative M-S bonds and the replacement of a pyridine molecule and a chlorine atom by an η(5)-cyclopentadienyl group in each metal center, affording the compounds [M(η(5)-C5H5)(N(t)Bu)(μ-S)]4 (M = Nb 9, Ta 10). These processes may develop through formation of the complexes [M4(η(5)-C5H5)2(μ-Cl)(N(t)Bu)4py2(μ3-S)2(μ-S)2](C5H5) (M = Nb 11, Ta 12), also obtained by reaction of 5 and 6 with cyclopentadienyllithium in 1:3 ratio. As further evidence, 11 and 12 led to complexes 9 and 10 by treatment with one more equivalent of the lithium reagent. The structural study of these metal sulfide clusters has been also performed by X-ray crystallography.

Molecular Design of Cyclopentadienyl Tantalum Sulfide Complexes

“…The trimetallic sulfide cluster [Ta 3 (η 5 -C 5 Me 5 ) 3 Cl 3 (μ 3 -Cl)­(μ-S) 3 (μ 3 -S)] ( 2 ) was prepared in a manner similar to that of the recently reported cube-type sulfide clusters [MCl­(NR)­py­(μ 3 -S)] 4 (M = Nb, Ta; R = t Bu, 2,6-Me 2 C 6 H 3 ) . Treatment of [Ta­(η 5 -C 5 Me 5 ) 3 Cl 4 ] ( 1 ) with (Me 3 Si) 2 S (3:4 ratio) in toluene heated at 100 °C for 72 h produced 2 cleanly as a yellowish green microcrystalline solid along with SiClMe 3 , as outlined in Scheme .…”

“…We reported previously the syntheses of cubane-type or incomplete cubane-type group 5 (Nb, Ta) sulfide clusters, which involved the distorted octahedral imido compounds [MCl 3 (NR)­py 2 ] (M = Nb, Ta) as building block complexes and hexamethyldisilathiane reagent, (Me 3 Si) 2 S, as a sulfur source . However, the scarce solubility exhibited by these species prevented exploration of their reactivity.…”

Coinage Metal Complexes with Di‐tertiary‐butyl Sulfide as Precursors with Ultra‐Low Decomposition Temperature

“…The silylated chalcogenoethers (R 3 Si) 2 E (E=S, Se, Te) have been employed as excellent starting reagents for the synthesis of metal chalcogenide nanomaterials and clusters owing to their ability to transfer the chalcogenide anion (E 2− ) under mild condition and versatility in reacting even with non‐conventional metal reagents or being employed in a variety of synthetic methods [16–18] . These silylated chalcogenoethers react readily with a metal reagent MX n (X=alkyl, halide, amide, carboxylate), where facile and homogeneous delivery of chalcogenide (E 2− ) to the metal center and M−E bond formation are promoted by the generation and elimination of the corresponding R 3 SiX [19–23] . On the contrary, the exploit of non‐silylated chalcogenoethers R 2 E (R=a non‐silylated alkyl group; E=S, Se, Te) have been mainly restricted to the elaboration of thin films by chemical vapor deposition technique requiring usually high temperature [24,25] .…”

“…[16][17][18] These silylated chalcogenoethers react readily with a metal reagent MX n (X = alkyl, halide, amide, carboxylate), where facile and homogeneous delivery of chalcogenide (E 2À ) to the metal center and MÀ E bond formation are promoted by the generation and elimination of the corresponding R 3 SiX. [19][20][21][22][23] On the contrary, the exploit of non-silylated chalcogenoethers R 2 E (R = a non-silylated alkyl group; E = S, Se, Te) have been mainly restricted to the elaboration of thin films by chemical vapor deposition technique requiring usually high temperature. [24,25] Only recently, we have employed nonsilylated selenoether ligands, particularly the ones having facile decomposition mechanism, [26] for the first time in the solutionphase synthesis of metal selenide NPs for the photocatalytic applications.…”

An Effective Route to Dinuclear Niobium and Tantalum Imido Complexes

“…Transition-metal complexes containing the unsaturated MNR linkage were known decades ago. As ancillary ligand, the involvement of this multiply bonded functionality in reactions and applications has been extensively reviewed. − Focusing our attention on niobium and tantalum, a variety of synthetic protocols afford imido complexes with nearly any organic substituent from available starting materials in high yield. ,, A common method to prepare imido complexes of formula [MCl 3 (NR)­L 2 ] comprises the reaction of MCl 5 with the corresponding amines NHRSiMe 3 and nitrogen-, oxygen-, and sulfur-donor molecules (L) in hydrocarbon solvents. − These compounds exhibit a pseudo-octahedral geometry with a six-coordinate metal center, where the imido ligand and one donor molecule (L) occupy axial positions. The trans imido ligand in these species labilizes the donor group located opposite to it, this latter being easily replaced in subsequent reactions. , Moreover, the strong labilizing effect of the imido groups on the donor ligand trans to the MNR bond makes it possible to form dinuclear or even polynuclear complexes.…”