Bonding characteristics of alkali-metal amides in solution and in the solid state: NMR and X-ray diffraction study of N-lithioindole-N,N,N',N'-tetramethylethylenediamine, N-sodioindole-N,N,N',N'-tetramethylethylenediamine, and N-sodioindole-N,N,N',N'',N''-pentamethyldiethylenetriamine

Alkali metal and magnesium enamides from metallation of the alkyl ligands [(2-Pyr)(SiMe3)CH2] and [6-Me-(2-Pyr)(SiMe3)CH2]: a solid state and ab initio study†

“…This raises the effective coordination of the metal and compensates for the relatively low formal coordination environment of four. The Na-H(21, 21Ј) distances in 1 of 3.07(2) and 3.12(3) Å, are significantly different from comparative distances in 3, Na(1)-H(21) 2.58 (8) and Na(2)-H(21) 2.74(8) Å, indicating that there are relatively strong compensatory agostic interactions in 3, similar to those observed in 6. This is much less pronounced in 1, especially when compared with those in the K analogue, 2, (see below), and is clearly a result of increased steric crowding.…”

The first structurally characterised sodium primary amide complex; synthesis and crystal structure of 2-PhOC6H4NHNa·NMe[(CH2)2NMe2]2

“…1 Molecular structure of 2-PhOC,H,NHNa-NMe[(CH2),-NMe,], 1 (hydrogen atoms omitted for clarity). Selected bond lengths (A) and angles (O): Na(1)-N(4) 2.419(3), Na(1)-N(4') 2.428(3), Na(1)-N(2) 2.528(3), Na(1)-N(3) 2.574(3), Na(1)-N(1) 2.725(3), Na(l)-C(S)3.1 14(4), Na(ltNa(1') 3.208(2), N(4)-Na(l)-N(4') 97.12(9), Na(l)-N(4)-Na(l') 82.88(9), C(5kN(2)-Na(l) 99.0(2)…”

An N-lithio-indole from the reaction of LiCH(TMS)2 and PhNC

“…When the sample was cooled, a second exchange process was observed. Thus, at 233 K the 7 Li-{ 1 H}-NMR signal was a broad peak, which at 193 K split into four separate signals, while the tmen protons were also found as four equal intensity signals at 213 K. As other signals in the 1 H-NMR spectrum were essentially unaffected by changes in temperature, we attribute above fluxional effects to conformational changes in the Li(tmen) metallacycles.…”

“…† The 1 H-NMR spectrum showed a characteristic signal for the CH(TMS) group at d 5.67 and 3 broad signals for the coordinated tmen ligands, the latter indicating that tmen was participating in a dynamic exchange process. The two signals in the 7 Li-{ 1 H}-NMR spectrum observed at ca. 300 K converged at 333 K into a singlet, indicating a rapid exchange between the two lithium atoms.…”