Solid-state structure of sulfur bis(trimethylsilylimide), S(NSiMe3)2, and multinuclear magnetic resonance studies of some sulfur bis(silylimides) in solution

Abstract

In the solid state sulfur bis(trimethylsilylimide) 1 has been shown t o adopt the € / Z configuration by singlecrystal X-ray diffraction (space group P i , triclinic). In solution sulfur bis(sily1imides) R(NSN)R' [R = R' = SiMe, 1 or Si,Me, 2; R = SiMe,, R' = Si,Me, 3 or SiMe,SiMe,(NSN)SiMe,are fluxional at room temperature. Comparison of the 'H. 13C, and, in particular, 15N N M R data indicates that 1 and 2 undergo rapid € / Z c ZIEisomerization even at 173 I<, whereas in the case of 3 and 4 this process is slowed at l o w temperature and the E/Z configuration prevails with the SiMe, group in the E position.Sulfur bis(trimethylsilylimide), S(NSiMe,), 1, has been extensively used as a versatile reagent in sulfur-nitrogen chemistry.' In principle, its structure in solution can be described by any of the three configurations Z / Z , E / E and E/Z (2 = syn, E = anti) which are generally possible for sulfur diimides, S(NR) 2 , bearing iden tical subs ti tuen ts. However, there appears to be conflicting evidence in the literature concerning the structure of 1. Analysis of the IR and Raman spectra3 inferred point group C2, indicating a distorted E/E configuration. In contrast a recent electron-diffraction study came to the conclusion that 1 adopts a distorted Z / Z configuration in the gas phase.4 Both 'H and 14N NMR spectra of 1 in solution show a single resonance signal.' A single signal was also found in the 15N NMR spectrum,6 although the reported S(' 5N) value differed considerably from the S(I4N) value. The conditions for recording the 15N NMR spectrum were probably not correct. All this prompted us to reinvestigate the solution-state NMR spectra of 1 and to compare the data with three other related sulfur diimides 2 (R = R' = Si2Me5),7 3 (R = SiMe,, R' = Si,Me,)7 and 4 [R = SiMe,, R' = SiMe,SiMe,(NSN)SiMe,]. A single-crystal X-ray analysis of 1 was carried out at -160 "C in order to establish its solid-state molecular structure.

Experimental and Theoretical Studies of Unusual Four‐Membered Metallacycles from Reactions of Group 4 Metallocene Bis(trimethylsilyl)acetylene Complexes with the Sulfurdiimide Me3SiN=S=NSiMe3

“…Free trimethylsilyl-substituted sulfurdiimide 3 exhibits two S-N double bonds of similar length (S-N1 1.523(1), S-N2 1.516(1) Å]; [11] when bound to a metal fragment, as in complex 4Ti, both bonds are elongated (av. S-N bond length in 4Ti 1.742 Å [12] ) and can be referred to as S-N single bonds (Σr cov = 1.74 Å [13] ).…”

The First Lanthanide Complexes with a Redox‐Active Sulfur Diimide Ligand: Synthesis and Characterization of [LnCp*2(RN=)2S], Ln=Sm, Eu, Yb; R=SiMe3

“…Structure and electrochemistry of the free ligand and EPR of its RA Neutral (Me 3 SiN=) 2 Si ss tructurally non-rigid. In the crystalline state it adopts the E,Z configuration and it features rapid E,Z$Z,E isomerization in solution [17] (see the Supporting Information). According to (U)B3LYP-D3/def2-TZVP calculations, the most stable configuration of both (Me 3 SiN=) 2 Sa nd [(Me 3 SiN= ) 2 ] À C in the gas phase and organic solution is E,Z ( Table S1 in the Supporting Information).…”

“…Neutral (Me 3 SiN=) 2 S is structurally non‐rigid. In the crystalline state it adopts the E , Z configuration and it features rapid E , Z ↔ Z , E isomerization in solution (see the Supporting Information). According to (U)B3LYP‐D3/def2‐TZVP calculations, the most stable configuration of both (Me 3 SiN=) 2 S and [(Me 3 SiN=) 2 ] − .…”

“…For full data, see Ref. and Table S3 in the Supporting Information. Particularly, the XRD structure of E , Z (Me 3 SiN=) 2 S is fairly well reproduced by the calculations, with the only significant deviation in the S−N−Si bond angle.…”

“…Figure 4 shows the low-energy spectra of these cations together with that of complex 1.T he energy spectrum of 1 + demonstrates ligand-field splittingo fe very 6 H J level of Sm 3 + into Stark sublevels [25] corresponding to an umber of Kramers doublets.T he ligand-field splitting within 300-400 cm À1 predicted for 1 + is similar to those obtained forg round-statem ultiplets of bis(phthalocyaninato) complexes of as eries of Ln III cations( 400-600 cm À1 ). [26] In turn, every Kramers doublet of 1 + is converted into aq uartet of split levels of complex 1 as ar esult of exchange [17]and Ta ble S3 in the SupportingInformation.Particularly,t he XRD structure of E,Z (Me 3 SiN=) 2 Si sf airly well reproduced by the calculations, with theo nly significant deviation in theS ÀNÀSi bond angle.…”