Diborane(4) compounds with bidentate diamino groups

Abstract

The reaction between B(2)(NMe(2))(4) and 1,2-(NH(2))(2)-4-Bu(t)C(6)H(3) affords the diborane(4) compound 1,2-B(2){1,2-(NH)(2)-4-Bu(t)C(6)H(3)}(2) as the exclusive product whilst the reaction between rac-1,2-(NH(2))(2)C(6)H(10) and B(2)(NMe(2))(4) also affords only the 1,2-isomer, i.e. 1,2-B(2){1,2-(NH)(2)C(6)H(10)}(2), which is shown to be the more stable isomer by computational methods. The previously reported compounds 1,1-B(2){1,2-(NH)(2)C(6)H(4)}(2) and 1,2-B(2){1,2-(NH)(2)C(6)H(4)}(2) both react with four equivalents of Bu(n)Li to give what are presumed to be tetra-anions which react further with MeI, SnClMe(3) or SnClPh(3) to give the tetrasubstituted products 1,1-B(2){1,2-(NMe)(2)C(6)H(4)}(2), 1,1-B(2){1,2-(NSnMe(3))(2)C(6)H(4)}(2) and 1,2-B(2){1,2-(NSnPh(3))(2)C(6)H(4)}(2) respectively. The compound 1,1-B(2){1,8-(NH)(2)C(10)H(6)}(2) has also been prepared from the reaction between B(2)(NMe(2))(4) and 1,8-diaminonaphthalene. Lithiation and subsequent reaction with SnClMe(3), SnCl(2)Me(2) or SnCl(2)Ph(2) affords 1,1-B(2){1,8-(NSnMe(3))(2)C(10)H(6)}(2), 1,1-B(2){1,8-(N(2)-μ-SnMe(2))C(10)H(6)}(2) and 1,1-B(2){1,8-(N(2)-μ-SnPh(2))C(10)H(6)}(2) respectively. All new compounds have been characterised by X-ray crystallography.

Luminescent Symmetrically and Unsymmetrically Substituted Diboranes(4)

“…Irradiation in the range of λ exc,max = 297 nm to λ exc,max = 341 nm prompts emission in solution in the range of λ em,max = 325 nm to λ em,max = 511 nm in the cases 5 , 8 and 9 (Table , Figure ) suggesting the cyclic 1,4‐diaza‐2,3‐diborinane scaffold as origin of a common fluorescence slightly modified by the different substituents. In comparison to Norman and Russell's cyclic 1,4‐diaza‐2,3‐diborinane isomer emission of cyclic 1,4‐diaza‐2,3‐diborinanes 5 and 9 is hypsochromically shifted, probably due to the absence of one half of the fused cyclic system. Upon formal replacement of one NMe 2 group in 5 by para ‐dimethylaminophenyl as in 9 , a bathochromic shift of 30 nm in emission is observed, which is indicative of the expansion of the conjugated system.…”

“…Upon formal replacement of one NMe 2 group in 5 by para ‐dimethylaminophenyl as in 9 , a bathochromic shift of 30 nm in emission is observed, which is indicative of the expansion of the conjugated system. Similarly, the presence of an additional aminophenyl substituent ( 8 ) results in a bathochromic shift compared to Norman and Russell's cyclic 1,4‐diaza‐2,3‐diborinane isomer . The emission band is split into two maxima at λ em,max = 473 nm and λ em,max = 511 nm due to vibronic coupling (the corresponding excitation band is at λ exc,max = 341 nm; Table , Figure ).…”

“…Norman and Russel et al isolated both possible isomers from the reaction between o ‐phenylenediamine and tetrakis(dimethylamino)diborane(4) via transamination . With R = Me at the nitrogen atoms, Norman and Russel found both isomers to be fluorescent . While diazaboroles are known to be fluorescent, 1,4‐diaza‐2,3‐diborinane derivatives have not been intensely investigated in this regard.…”

Direkte Umwandlung eines terminalen Borylen‐ in einen terminalen Phosphinidenkomplex

“…[7b-e, 23] Die trigonal-planare Geometrie um das Stickstoffatom sowie der N-B-Abstand (1.428 (3) )b estätigen das Vorliegen einer typischen R 2 N = BR 2 -Einheit (N-B 1.40-1.44 ). [24] Die P-N-B-Clund Mn-P-N-B-Fragmente sind, wie aus Torsionswinkeln von 166.1 (1) [25] Einer NCS-Analyse ("natural chemical shielding") [26] dieser 31 P-NMR-Resonanz zufolge gehen 94 %d er Abschirmung des Phosphorkerns von den Kernorbitalen aus,d ie jedoch durch die starken Entschirmungseffekte hauptsächlich der P-Mn-Bindung (61 %) und des freien Elektronenpaars am Phosphoratom (17 %) überkompensiert werden. Dichtefunktionalrechnungen haben überdies gezeigt, dass die stärkere Entschirmung in 2 im Vergleich zu Cartys kationischen Eisenkomplex [Cp*-(OC) 2 FePNiPr 2 ] + auf folgenden Unterschieden beruht: 1) Gegenwart von Mn I anstelle von Fe II ,2 )Ersatz von Cp* durch Cp und 3) starker Einfluss des Borliganden auf die P-N-Wechselwirkung.…”

Direct Conversion from Terminal Borylene into Terminal Phosphinidene

“…[7b-e,23] Thet rigonal planar geometry of the nitrogen atom, and the NÀBd istance of 1.428(3) are both as expected for aR 2 N=BR 2 -type linkage (typically between 1.40-1.44 ). [24] TheP -N-B-Cl and Mn-P-N-B moieties are almost coplanar, with torsion angles of 166.1(1)8 8 and 166.6(2)8 8 respectively.T his suggests some degree of p-delocalization along the Mn-P-N-B spine,d espite the long P À Nd istance ( Figure 3). Complex 2 was characterized by NMR spectroscopy.I ts 11 BNMR spectrum showed abroad singlet at 49.8 ppm, which is typical of at hree-coordinate boron nucleus.T he 31 P{ 1 H} NMR spectrum revealed ah eavily deshielded chemical shift at 1283 ppm as ab road singlet, which is the most deshielded 31 PNMR shift reported for any isolated electrophilic terminal phosphinidene complex (cf.…”