TY - JOUR
T1 - Synthesis and reactivity of air-stable isolable anionic Group 6 molybdenum and tungsten carbene complexes with a metal-centred negative charge
AU - Lalor, Fergus J.
AU - O'Neill, S. A.
PY - 2003/11/1
Y1 - 2003/11/1
N2 - The first air-stable anionic carbene complexes with a metal-centred negative charge [TpMe2(CO)2M=C(CN) 2]- (3a, M=Mo; 3b, M=W), [TpMe2,4Cl (CO)2Mo=C(CN)2]- (4), [Tpi-Pr,4Br(CO)2Mo=C(CN)2] - (5) and [TpMe2(CO)2Mo= C(CN)R]- (11a-d, R=substituted alkyl) have been synthesised by addition of cyanide anion to the corresponding chlorocarbyne complexes 1, 6, 7 or to the alkylcarbyne complexes 9a-d. Carbene complexes 3 and 11 are stereochemically rigid with the plane of the carbene ligand coinciding with the molecular mirror plane. The electron-rich carbene carbons in these complexes show some of the most highly shielded values of δ Ccarbene so far observed. The dicyanocarbene complexes (3) did not give stable products with electrophiles but the cyano(alkyl)carbene complexes (11b-d) could be doubly alkylated at the CN nitrogen to give the cationic dialkylaminoalkyne complexes [TpMe2(CO)2Mo{η2(C,C)Me2 N-C≡C-R}]+ (12). Complex 11a (R=C(CN)2 CH3) eliminates [CH3C(CN)2]- in the presence of MeI and yields purple TpMe2(CO)2 M≡C-CN (2a), the first example of a cyanocarbyne complex and a presumed intermediate in the formation of 3a.
AB - The first air-stable anionic carbene complexes with a metal-centred negative charge [TpMe2(CO)2M=C(CN) 2]- (3a, M=Mo; 3b, M=W), [TpMe2,4Cl (CO)2Mo=C(CN)2]- (4), [Tpi-Pr,4Br(CO)2Mo=C(CN)2] - (5) and [TpMe2(CO)2Mo= C(CN)R]- (11a-d, R=substituted alkyl) have been synthesised by addition of cyanide anion to the corresponding chlorocarbyne complexes 1, 6, 7 or to the alkylcarbyne complexes 9a-d. Carbene complexes 3 and 11 are stereochemically rigid with the plane of the carbene ligand coinciding with the molecular mirror plane. The electron-rich carbene carbons in these complexes show some of the most highly shielded values of δ Ccarbene so far observed. The dicyanocarbene complexes (3) did not give stable products with electrophiles but the cyano(alkyl)carbene complexes (11b-d) could be doubly alkylated at the CN nitrogen to give the cationic dialkylaminoalkyne complexes [TpMe2(CO)2Mo{η2(C,C)Me2 N-C≡C-R}]+ (12). Complex 11a (R=C(CN)2 CH3) eliminates [CH3C(CN)2]- in the presence of MeI and yields purple TpMe2(CO)2 M≡C-CN (2a), the first example of a cyanocarbyne complex and a presumed intermediate in the formation of 3a.
KW - Anionic carbene complexes
KW - Chlorocarbyne
KW - Cyanocarbyne
KW - Molybdenum
KW - Tungsten
UR - https://www.scopus.com/pages/publications/0142088820
U2 - 10.1016/S0022-328X(03)00755-1
DO - 10.1016/S0022-328X(03)00755-1
M3 - Article
AN - SCOPUS:0142088820
SN - 0022-328X
VL - 684
SP - 249
EP - 265
JO - Journal of Organometallic Chemistry
JF - Journal of Organometallic Chemistry
IS - 1-2
ER -