Anionische Komplexe [Mo₂(O₂CPh)₄X₂]^2⊖ mit X = N₃, Cl, Br. Die Kristallstruktur von (PPh₄)₂[Mo₂(O₂CPh)₄Cl₂] · 2CH₂Cl₂ / Anionic Complexes [Mo₂(O₂C-Ph)₄X₂]^2⊖ with X = N₃, Cl, Br. The Crystal Structure of (PPh₄)₂[Mo₂(O₂C-Ph)₄Cl₂] · 2CH₂Cl₂

Abstract

The syntheses and IR spectra of the complexes [Mo 2 (O 2 C-Ph) 4 X 2 ] 2⊖ with X = N 3 , CI, Br and the counter ion PPh 4 ⊕ are reported. The azido and the bromo complexes are obtained from a solution of [Mo 2 (O 2 CPh) 4 ] with PPh 4 N 3 in pyridine or by reaction with PPh 4 Br in CH 2 Br 2 , respectively. When (PPh 4 ) 2 [Mo 2 (O 2 CPh) 4 (N 3 ) 2 ] is dissolved in CH 2 Cl 2, nitrogen is evolved and the complex with X = CI is obtained. The crystal structure of (PPh 4 ) 2 [Mo 2 (O 2 CPh) 4 Cl 2 ] · 2CH 2 Cl 2 was determined from X-ray diffraction data (5676 observed independent reflexions, R = 0.042). It crystallizes in the monoclinic space group P2 1 /n with four formula units per unit cell; the lattice constants are a = 1549, b = 1400, c = 1648 pm, β = 94.6°. The centrosymmetric [Mo 2 (O 2 CPh) 4 Cl 2 ] 2⊖ ion has a rather short Mo-Mo bond of 213 pm, whereas the MoCl bonds are very long (288 pm)