Zwitterionic and biradicaloid heteroatomic cyclopentane derivatives containing different group 15 elements

The formal cyclopentane-1,3-diyl derivatives [E1(μ-NTer)2({E2C} = NDmp)] (Ter = 2,6-dimesityl-phenyl, Dmp = 2,6-dimethylphenyl) were prepared by 1,1-insertion of CNDmp into the N–E2 bond of [E1(μ-NTer)2E2] (E1 = N, P; E2 = P, As).

Fluorobenzene was dried over CaH 2 , distilled and degassed prior to use. Diethyl ether, THF, toluene and benzene were dried over Na/benzophenone and freshly distilled prior to use. NMR: 31 P{ 1 H}, 13 C{ 1 H} and 1 H NMR spectra were recorded on BRUKER spectrometers AVANCE 250, AVANCE 300 and AVANCE 500, respectively. The 1 H and 13 C NMR chemical shifts were referenced to the solvent signals. [6] The 31 P NMR chemical shifts are referred to H 3 PO 4 (85%) respectively. C 6 D 6 was dried over Na and freshly distilled prior to use.

MS:
Finnigan MAT 95-XP from Thermo Electron was used.
X-ray Structure Determination: X-ray quality crystals of all compounds were selected in Fomblin YR-1800 perfluoroether (Alfa Aesar) at ambient temperatures. The samples were cooled to 173(2) K during measurement. The data were collected on a Bruker Apex Kappa-II CCD diffractometer or on a Bruker-Nonius Apex X8 CCD diffractometer using graphite monochromated Mo K α radiation (λ = 0.71073). The structures were solved by direct methods (SHELXS-2013) [7] and refined by full-matrix least squares procedures (SHELXL-2013). [8] Semi-empirical absorption corrections were applied (SADABS). [9] All non-hydrogen atoms were refined anisotropically, hydrogen atoms were included in the refinement at calculated positions using a riding model.

Synthesis of Ter 2 N 2 PAsCNDmp (2PAs)
To a violet solution of [P(µ-NTer) 2 As] (181 mg, 0.246 mmol) in 4 ml benzene, a colourless solution of CNDmp (33 mg, 0.252 mmol) in 2 ml was added within 5 minutes. The solution turned grey and finally green within 10 minutes. Afterwards, volatiles were removed in vacuo until crystallization commenced (approx. 0.5 ml). The solution was left undisturbed overnight, resulting in the deposition of a green precipitate. The supernatant was filtered off (sintered glass frit) and the solid was dried in vacuo (150 mg, 0.168 mmol, 68%).

Computational Details
Utilizing the experimental structural data, all calculations were carried out with the Gaussian 09 package of molecular orbital programs. [10] The wave functions for the crystal structures were optimized with a 6-31G(d,p) basis set on the pbe1pbe level of density functional theory and the optimized structures were checked to be a minimum on the energy hypersurface. For Sb a relativistic pseudopotential was used, Sb: ECP46MDF 4 46.