Ditrielanes (R3Si)2E−E(SiR3)2 and Heterocubanes (R3Si)4E4Y4 (R3Si =tBu3Si,tBu2PhSi; E = Al, Ga, In, Tl; Y = O, Se)

Abstract

3 SiCl. According to X-ray structure analyses, the ditrielanes contain two planar groups R 2 EE which are orthogonal to each other (R = R*; angle REER ca. 90°) or nearly orthogonal (R = RЈ; angle REER ca. 80°). All compounds are deeply colored. The λ max value of the visible absorption shifts with increasing atomic number of E and with the increasing angle between the R 2 EE planes to longer wavelengths (ruby R− besides the mentioned ditrielanes − are presented.In fact, except for the compounds dealt with in this publication, only three other examples of silyl-ditrielanes, namely [(Me 3 Si) 3 Si] 4 E 2 with E ϭ Ga, [9] In, [10] Tl [11] have been published to date. On the other hand, some organyland aminyl-ditrielanes R 4 E 2 are known with R ϭ

NMR parameters of the tetrahedrane [Fe2(CO)6(μ-SNH)], studied by experiment and DFT

“…Chemical shifts δ 59 Co or δ 55 Mn of the cobalt or manganese carbonyl complexes are instructive examples in this context, since the δ values cover large ranges [27,28]. As shown previously, the δ 57 Fe values can be calculated with reasonable Scheme 2 Isolobal replacement of Fe(CO) 3 fragments with BH, starting from 1 accuracy [26,29], although errors of ± 200 ppm may be encountered [30]. The coupling constant 1 J( 57 Fe, 57 Fe) in 1 is hardly accessible by experimental methods without 57 Fe labelling.…”

“…Previously, we have measured the 13 C and 15 N NMR spectra of 1 at room temperature and determined the coupling constant 1 J( 57 Fe, 15 N) = 6.1 Hz in natural abundance of the isotopes [18]. In the present work, we report lowtemperature 13 C NMR data of 1, including the coupling constants 1 J( 57 Fe, 13 C), and the first example of a 57 Fe chemical shift for a complex containing the (OC) 3 Fe-Fe(CO) 3 unit. After optimizing the geometry of 1 by DFT calculations [B3LYP/6-311 + G(d,p)], the NMR parameters such as chemical shifts and coupling constants of 1 were calculated at the same level of theory.…”

“…Isolobal replacement of the Fe(CO) 3 fragments with BH units leads to tetrahedrane-type structures. Such a structure is preferred as long as one Fe(CO) 3 moiety is left (2), whereas it becomes energetically less favored if both Fe(CO) 3 units are replaced (3).…”

“…Tetrahedrane-type structures are common in both main group [1][2][3][4][5][6] and transition metal chemistry [7][8][9][10][11][12]. We have been interested for some time in aza-diferra-thiatetrahedranes, since the parent hexacarbonyl derivative 1 can be obtained in good yield (>50%) from the reaction of bis(trimethylsilyl)sulfur diimide with Fe 3 (CO) 12 , followed by chromatography on silica [13].…”

“…After optimizing the geometry of 1 by DFT calculations [B3LYP/6-311 + G(d,p)], the NMR parameters such as chemical shifts and coupling constants of 1 were calculated at the same level of theory. Changes in the bonding situation by stepwise isolobal replacement of the Fe(CO) 3 with BH fragments (Scheme 2) have been examined by optimizing the respective geometries of 2 and 3. The complex 2 is unknown, and alternatively 16e complexes with fourmembered cyclic structures such as 2a (Fe-BH-NH-S) and 2b (Fe-NH-BH-S) are conceivable.…”