�ber r�umliche Behinderung chemischer Reaktionen

The Manifold Structural Chemistry of Alkali Metal Enediamide Complexes

“…The bonding situation of Li1 is better described as η 4 -coordination by the C 2 N 2 π-system, as being strongly displaced from the DAD plane by 77.6(2)°and resulting in a "piano-stool" arrangement which is completed by a terminal and a weakly bonded μ-bridging THF ligand. Symmetric σ 2 -coordination of the enediamide ligand such as in 4 has been previously observed in Li 2 ( Ph2 DAD pTol )(THF) 4 [35] and in Li 2 ( (MePhN)2 DAD pTol )(Et 2 O) 3 , [36] while σ,π-coordination similar as in 6 has been seen only in a related ortho-phenylenediamide derivative [42] (cf. Table 2).…”

“…Mode [b] ) R e f . M1 M2 [36] Li 2 ( H2 DAD Dipp )(DME) 2 [31] , this work [40] Li( R2 DAD Tipp )(μ-THF)(THF) 2 [33] [Na 2 ( Me2 DAD Mes )(Et 2 O) 2 ] 2 XOQQEA 46.8(1) (σ) 74.7(1) (π) [33] [Na 2 ( Me2 DAD Mes )(THF) 2 ] 2 XOQQIE 50.5(1) (σ) 66.6(1) (σ + π?) [33] [Na 2 ( Me2 DAD Dep )] n XOQQOK 45.5(2) (σ) 76.7(2) (π) [33] Na 2 ( R2 DAD Dipp )(μ-Et 2 O)(Et 2 O) 2 (R 2 = C 10 H 6 , acenaphthylene residue) UKAWEI 23.9(2) (σ) 76.6(2) (π) [43] Na 2 ( Me2 DAD Dipp )(THF) 4 (7) 38.2(1) (σ) 76.6(1) (π) this work K 2 ( H2 DAD Dipp )(μ-THF)(THF) 4 (5) IKUVOA 40.6(2) (σ) 67.4(2) (σ) [11] [K 2 ( H2 DAD Dipp )(THF)] n GUCRUS 57.3(1) (σ) 80.5(1) (π) [32] K 2 ( Me2 DAD Dipp )(DME) 2 (THF) VERPEP 41.0(2) (σ) 77.9(2) (π) [34] K 2 ( R2 DAD CH2Py )(THF) 3 (R 2 = buta-1,4-diyl) REQREM 52.0(2) (σ) 61.6(2) (σ) [37] K 2 ( Me2 DAD Dipp )(μ-THF)(THF) 2.5 (8) 29.6(2) and 30.5(2) (σ) 75.7(2) and 72.8(1) (π) this work…”

“…[32,33] The M-N bond lengths in 3-8 (M = Li, Na, K) are all within the expected ranges for enediamide complexes. [11,[31][32][33][34][35][36][37][40][41][42][43] The values are primarily determined by the coordination number of the metal and do not change systematically in going from the H2 DAD Dipp to the Me2 DAD Dipp ligand. While the M-N distances do not differ significantly between σand π-coordinated metals as well, the corresponding M···C separations to the DAD core correlate clearly with the displacement angle δ (cf.…”

“…[29,30] A few structurally characterized alkali metal enediamide complexes derived from 1 and 2 have been reported previously. These include lithium, sodium and potassium derivatives of 1, [11,31,32] 2, [33,34] Ph2 DAD pTol (pTol = para-tolyl), [35] and additionally functionalized derivatives like (MePhN)2 DAD pTol [36] and R2 DAD CH2Py (R 2 = buta-1,4-diyl, CH 2 Py = CH 2 -4-pyridyl) [37] (cf. Table 1).…”

A facile access to indigodianiles

“…In 1999 we reported a formation reaction of indigodianiles starting from bis-imidoylchlorides of oxalic acid 3 [4]. Such acylderivatives are valuable building blocks for numerous heterocyclic compounds which were often formed via cascade reactions [5].…”