104130-61-2Relevant academic research and scientific papers
Cationic 2-azaallenylidene complexes of chromium and tungsten. Complexes with a novel metallaheterocumulene system
Seitz, Friedrich,Fischer, Helmut,Riede, Jürgen,Vogel, Jürgen
, p. 2187 - 2192 (2008/10/08)
The reaction of (CO)5M[C(OEt)N=CR2] with BF3 yields 2-azaallenylidene complexes [(CO)5M=C= N=CR2]BF4 (M = Cr ([3]BF4), W ([4]BF4); CR2 = C(C6H4Br-4)2 (a), CPh2 (b), C(C6H4OMe-4)2 (c), C(C6H4)2O (d), C(2,4,6-C6H2Me3)2 (e), C(CMe3)2 (f)). The abstraction of Cl- from (CO)5Cr-C≡N-CCl3 by AlCl3 gives [(CO)5Cr=C=N=CCl2]AlCl4 ([3a]AlCl4). IR, 13C NMR, and electronic spectra reveal the high degree of electron delocalization within the metallaheterocumulene system. The structure of [3d]-BF4·CH2Cl2 has been determined by an X-ray diffraction analysis (crystal data: monoclinic, space group P21/c, a = 15.811 (4) A?, b = 12.657 (4) A?, c = 12.966 (3) A?, β = 111.98 (2)°, and Z = 4). The Cr-C-N-C fragment is almost linear (Cr-C-N = 179.0 (5)°; C-N-C = 171.1 (5)°) and allows the formation of two orthogonal π-systems Both C-N distances (118.4 (7) and 134.3 (7) pm, respectively) differ significantly. Therefore, the complexes are best described as resonance hybrids of the two limiting structures A and B: the 2-azaallenylidene complex A and the carbocationic isonitrile complex B. [3d]BF4 reacts with Me3N+-O- to yield the ketone O=C(6H4)2O. On near-UV irradiation of [3b]BF4 and [3d]BF4, the olefins R2C=CR2 (CR2 = CPh2, C(C6H4)2O) are formed.
