Organic syntheses via transition metal complexes. 80. Allenylidene complexes from [(2-aminoethenyl)carbene] chromium complexes

Article abstract of DOI:10.1021/om00007a018

Allenylidene complexes (CO)₅Cr=C=C=C(NRR¹)Ph (5a-d) (NRR¹ = NMe₂, NMePh, NEtPh, indolinyl) are formed on reaction of (2-aminoalkenyl)carbene complexes (CCO₅-Cr=C(OEt)-CH=C(NR¹)Ph (4a-d) with aluminum chloride in carbon disulfide/dichloromethane in 53-73% isolated yield. The X-ray structure of complex 5d [NRR¹ = NMePh; monoclinic space group P2₁/c (No. 14), a = 12.989(1) ?, b = 13.520(2) ? c = 12.546(1) ?, Z = 4, R = 0.044, R_w2 = 0.143] indicates that a polarized iminium-alkynyl structure (CO)₅Cr^--C≡CC(=N⁺MePh)Ph gives a more adequate description of the bond distances than the allenylidene structure.