[2 + 2]‐Cycloaddition von Iminoboran und Iminophosphan

Abstract

[2 + 21-Cycloaddition Products from lminoborane and IminophosphaneThe iminoborane Bu -B = N-tBu (la) and the iminophosphanes R2N -P = N -R' (2a, b) undergo a cyclisation to the corresponding 1,3,2,4-diazaphosphaboretidines (3a, b). Wie anhand zweier Diazadiboretidine vom Typ 4 mittels Rontgenstrukturanalyse nachgewiesen wurde, liegt bei dieser Verbindungsklasse wohl im allgemeinen ein planarer Vierring mit koplanaren Nachbaratomen vor. Auch die NPNP-Vierring-Verbindung 5a ist planar gebaut, die beiden Nachbaratome Si sind hierzu koplanar angeordnet, nicht jedoch die P-gebundenen Gruppen NR,, die aus der Vierringebene in trans-Stellung zueinander herausragen. Es liegt nahe, den Verbindungen 3a, b einen planaren NPNB-Vierring mit koplanaren Nachbaratomen zuzuschreiben mit Ausnahme des nicht koplanaren N-Atoms der NR2-Gruppe. Hierfur spricht die Verwandtschaft der NMR-Signale von 4a und der Iminoboran-Halfte von 3a, b (Tab. 1) sowie von Sa, b und der Iminophosphan-Halfte von 3a, b (Tab. 2,3). Aus den NMR-Daten von 5a wurde eine unerwartet hohe Barriere fur die Rotation der N(SiMe3)2-Gruppe um die PN-Achse abgeleitet3). Wir finden jetzt ebenfalls im NMR-Spektrum bei Raumtemperatur eine Nichtaquivalenz der beiden Reste R 0 Verlag

Novel [2 + 2] Cycloaddition Reactions of (Dimethylamino)bis(trifluoromethyl)borane, (CF3)2BNMe2, with N-Sulfinylsulfonamides, Aminoiminophosphines, Carbodiimides, and a Keteneimine

“…Compounds 2a − e and 3a − e are the first examples and four-membered rings where both boron and nitrogen are tetracoordinated. However, related cycloadducts with tricoordinate boron and nitrogen have been obtained with aminoiminophosphines and iminoboranes …”

An Element‐Substituted Cyclobutadiene Exhibiting High‐Energy Blue Phosphorescence

“…[14][15][16][17][18][19][20][21] Indeed, while CBD is extremely reactive,i ts BN analogue,1 ,3,2,4-diazadiboretidine (DADBT,F igure 1b)i sachemically stable and isolable species when sterically bulky groups are attached to the boron and nitrogen atoms for kinetic protection. [22][23][24][25][26][27][28] Quantum chemical calculations have suggested that the parent DADBT (B 2 N 2 H 4 )i nt he S 0 state has an onaromatic or weakly Hückel antiaromatic character depending on slight structural differences. [29] Form ore detail, DADBT in the S 0 state with a( quasi-)planar rhombic structure is ac losed-shell species,i nw hich the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are localized on the nitrogen and boron atoms,r espectively (Figure 1b).…”

Formation of the spirocyclic, Si-centered cage cations [ClP(NSiMe3)2Si(NSiMe3)2P5]+ and [P5(NSiMe3)2Si(NSiMe3)2P5]2+

“…For structurally related compounds, this was rationalized by the close proximity of the CH 3 -groups to the lone pair of electrons on the adjacent P atom. 20 Due to the same reason, two relatively large 4 J (PH) coupling constants (3.4 and 3.7 Hz) were observed for the isomer of 9 in which the SiCl 3 -group points towards the face of the four-membered ring (9′). 19 The chlorosubstituted Si atom in 9 appears as doublet resonance in the typical range in the 29 Si NMR spectrum (δ(Si) = −27.3 ppm) 21 It is assumed, that 7 is obtained from 9 via an intermediate of type 10 which forms upon rotation 22 of the P-N bond involving the SiCl 3 -substituted N atom and inversion 23 of one of the P centers in 9 (Scheme 2).…”