A tetranuclear samarium(ii) inverse sandwich from direct reduction of toluene by a samarium(ii) siloxide

Abstract

The dinuclear SmII complex, [Sm2L4(dme)] (L = OSi(OtBu)3), is easily obtained from the protonolysis reaction of [Sm{N(SiMe3)2}(thf)2] with HOSi(OtBu)3. This complex reacts slowly with toluene, resulting in the isolation of the triple-decker arene-bridged SmII complex, [{Sm2L3}2(μ-η6:η6-C7H8)], in 44% yield. This reactivity provides the first example of unambiguous arene reduction by an isolated SmII species. In contrast, reduction of [SmL3]2 afforded the inverse sandwich complex, [{KSmL3}2(μ-η6:η6-C7H8)].

Carbon dioxide reduction by dinuclear Yb(ii) and Sm(ii) complexes supported by siloxide ligands

“…One lanthanide ion in the structure of 1-Sm is five-coordinated by a terminal siloxide ligand in a bidentate fashion and by three bridging siloxides while the second metal ion is six-coordinated by three bridging siloxide ligands in a bidentate fashion. The crystal structure of the solvate complex [Sm2L4(DME)], 17 was reported previously. The removal of the bound DME solvent from [Sm2L4(DME)], does not results in a decreased stability of the resulting Sm(II) complex 1-Sm because of the multiple coordination modes of the siloxide ligand.…”

“…On the other hand , the Sm-Osiloxide bond lengths in 1-Sm fall in a slightly larger range (2.387(5) -2.735(5) Å) compared to the mononuclear [SmL4K2] complex (2.381(2) -2.6659(18) Å) 8c and the dimeric [Sm2L4(dme)] complex (2.383(12) -2.692(13) Å). 17 Figure 1. Solid-state molecular structure of 1-Sm (50% probability ellipsoids).…”

“…The complex [Sm2L4(DME)] was previously shown to slowly react at room temperature with toluene affording, after few days, the tetranuclear divalent samarium sandwich complex [{Sm2L3}2(μ-η 6 :η 6 -C7H8)]. 17 Spectroscopic 1 H NMR study of 1-Sm in Tol-d8 at room temperature shows that the removal of the DME molecule from the coordination environment of the samarium metal centre does not impact the formation of this multiple decker complex. Notably, the 1 H NMR spectra of 1-Sm in Tol-d8 over time show the appearance after 5 days of a signal at d = 1.08 ppm assigned to the complex [{Sm2L3}2(μ-η 6 :η 6 -C7H8)].…”

CS2 Reductive Coupling to Acetylenedithiolate by a Dinuclear Ytterbium(II) Complex

“…[8c, 12] As such, the reaction of polynuclear lanthanide complexes with CS 2 is of interest because it may allow to trap reactive intermediates or stabilize unusualreactionproducts.Here, we report the reduction of CS 2 by the dinuclear Yb II complex [Yb 2 L 4 ], 1 [L = (OtBu) 3 SiO À ], [13] whicha llowed to trap for the first time ap roduct of CS coupling from CS 2 reduction in the complex [Yb 2 L 4 (C 2 S 2 )], 2,together with the CS 2 2À bridged key intermediate [Yb 2 L 4 (CS 2 )], 3.Crystals of the homoleptic complex 1,w ere obtained by recrystallization from n-hexane at À40 8Co ft he [Yb 2 L 4 (DME)] complex prepared as previously described for [Sm 2 L 4 (DME)]. [14] The solid-state structure of 1 is presentedi nF igure 1a nd showst he presence of ad imer in whicht wo Yb II ions are bridged by three oxygen atoms from three different siloxide ligands in an on-symmetric fashion. The YbÀO siloxide bond lengths in 1 range from 2.265(2) to 2.570(3) ,a nd are consistent with the values previously reported for the divalent ytterbium complex [YbL 4 K 2 ][ 2.251(6)-2.571 (6) ].…”

“…Crystals of the homoleptic complex 1,w ere obtained by recrystallization from n-hexane at À40 8Co ft he [Yb 2 L 4 (DME)] complex prepared as previously described for [Sm 2 L 4 (DME)]. [14] The solid-state structure of 1 is presentedi nF igure 1a nd showst he presence of ad imer in whicht wo Yb II ions are bridged by three oxygen atoms from three different siloxide ligands in an on-symmetric fashion. The YbÀO siloxide bond lengths in 1 range from 2.265(2) to 2.570(3) ,a nd are consistent with the values previously reported for the divalent ytterbium complex [YbL 4 K 2 ][ 2.251(6)-2.571 (6) ].…”