Beiträge zur Chemie des Bors, 140. Bor‐, Aluminium‐ und Galliumhalogenid‐Addukte einer Tetraaminodibor‐Verbindung

Abstract

Die Tetraaminodibor-Verbindung 1 lagert die Trihalogenide EX3 (E = B, Al, Ga; X = CI, Br, I) zu 1 : 1-bzw. 1 : 2-Koordinationsverbindungen an. Von diesen zeigt nur das thermisch stabilere BBr,-Addukt 1 b in Losung im Gegensatz zu den AIC1,-und GaCl,-Addukten kein fluktuierendes Verhalten. Die 1 : 2-Addukte sind starr, und nach NMR-Spektren bildet sich nur die meso-Form. Die Struktur der 1 : 1-Addukte wurde durch Rontgenstrukturanalyse von l g gesichert; die Einkristalle enthielten ein R-konfiguriertes Molekiil. Durch die Addition nimmt der sonst planare Diazaborolidin-Ring Briefumschlag-Konformation an.Contributions to the Chemistry of Boron, 1401)

Diborane(4) compounds with bidentate diamino groups

“…Having established that it was possible to substitute all NH hydrogens in compound 2a via lithiation and subsequent reaction with an electrophile (MeI or SnClMe 3 ), although not to isolate a tetra-anionic product, we examined a similar reaction with the 1,2-isomer 2b. Thus reaction of 2b with four equivalents of Bu n Li followed by treatment with excess SnClPh 3 afforded the tin derivative 1,2-B 2 {1,2-(NSnPh 3 ) 2 C 6 H 4 } 2 (7) in good yield. The structure of 7 was established by X-ray crystallography (Fig.…”

“…B-B distances are short (cf. 9 and 10) and t is small [11, B-B 1.645(3) A ˚; t 0 • ; 12, B-B 1.648 (7), 1.651(7) A ˚; t 0 and 6.4 • ], both resulting from the constraints imposed by the five-membered rings involving the tin atoms. As a final part of this study, we examined the electronic spectra of both 4 and the corresponding 1,2-isomer, 1,2-B 2 {1,2-(NMe) 2 C 6 H 4 } 2 (13), derived from the reaction between 2b, four equivalents of Bu n Li and an excess of MeI (full details of the preparation, structure and electrochemistry of 13 will be reported elsewhere).…”

“…4 A less well studied group incorporates chelating diamides where a key parameter used in describing the structures is the angle (t) between the N 2 B planes, i.e. t = 0 • describes a planar (eclipsed) structure and t = 90 7 All of these compounds with chelating groups adopt the 1,1-isomeric structure A as opposed to the alternative 1,2-isomeric form B although in a recent paper, we described the synthesis, structural characterisation and a computational analysis of both isomers of the diaminobenzene derivative B 2 {1,2-(NH) 2 C 6 H 4 } 2 (2), i.e. 1,1-B 2 {1,2-(NH) 2 C 6 H 4 } 2 (2a) [B-B 1.678(5) A ˚, t 0 • ] and 1,2-B 2 {1,2-(NH) 2 C 6 H 4 } 2 (2b) [B-B 1.649(3), 1.651(3) A ˚, t 0 • ].…”

Reactions of Amino-imino-boranes with Transition Metal Halides and Substituted Transition Metal Halides

“…This also holds for the rather long axial Ti-N3 distance of 2.330(3) A which is 0.257 A longer than the equatorial Ti-Nl bond of 1.933(3) A. Taking these data into account it is not surprising that there are three significantly differ ent B-N bond lengths: B-Nl of 1.434(4), B1-N2 of 1.460(4) and B1-N3 of 1.505(3) Ä, the longest falling into the range for BN single bonds with tetracoordinated nitrogen atoms [11]. The shortest B-N bond results from the three-coordinated N atom N 1 which resides in a planar environment and allows for BN 7r-bonding with the boron atom because the C2N unit of the tmp ligand is almost perpendicular to the BN2 ring unit preventing 7r-bonding.…”

2,6‐Bis(diazaboryl)pyridine – A Ligand with Hemilabile Donor and Lewis Acid Functionalities

“…In 1984, Nöth and co‐workers reported adduct formations of selected diazaborolidines with group 13 halides (e.g. 1,3‐dimethyl‐2‐phenyl‐1,3,2‐diazaborolidine and AlCl 3 , Figure , bottom) . However, the reported adduct is labile and the triel halide can be abstracted by addition of pyridine …”