TY - JOUR
T1 - Thirteen-Electron Manganese(II) Tetraalkyls. Synthesis, Characterization, and X-ray Crystal Structures of [Li(tmed)]2[MnMe4] and the “β-Unstable” Species [Li(tmed)]2[MnEt4] and [Li(tmed)]2[Mn(CH2CH2-t-Bu)4]
AU - Morris, Robert J.
AU - Girolami, Gregory S.
PY - 1989/6
Y1 - 1989/6
N2 - Alkylation of diethyl ether solutions of MnCl2 with 4 equiv of LiR (R = Me, Et, n-Bu, t-Bu, CH2SiMe3 or Ph) in the presence of N, N, N', N'-tetramethylethylenediamine (tmed) gives pale-colored divalent tetraalkylmanganates of stoichiometry [Li(tmed)]2[MnR4] in good yields. In the case of Li(t-Bu), a side reaction with diethyl ether leads to the formation of ethylene and the eventual isolation of the insertion product [Li(tmed)]2[Mn(CH2CH2-t-Bu)4]; the tert-butyl complex [Li(tmed)]2[Mn(t-Bu)4] could not be prepared even in other solvents. These 13-electron peralkyl species are stable at room temperature and are among the few well-characterized compounds of their type. The alkyls that contain β-hydrogen atoms are remarkably resistant to β-elimination. The single-crystal X-ray structures of [Li(tmed)]2[MnMe4] (1), [Li(tmed)]2[MnEt4] (2), and [Li(tmed)]2[Mn(CH2CH2-t-Bu)4] (3) have been determined, and compounds 2 and 3 are the first structurally characterized transition-metal peralkyls that contain β-hydrogen atoms. The coordination geometries around the manganese centers are essentially tetrahedral, and there are no agostic Mn•••H-C interactions. The Li cations each interact with two a-carbon atoms of the alkyl ligands and bridge opposite edges of the tetrahedron to give nearly linear Li•••Mn•••Li arrays. Crystallographic data (Mo Ka, X = 0.71073 A): 1, space group P21/c with a = 13.591 (2) Å, b = 15.190 (3) Å, c = 12.007 (2) Å, β = 94.27 (1)°, V = 2472 (1) Å3, Z = 4, T = 223 K, RF = 0.062, RwF = 0.068 on 179 variables and 1812 data; 2, space group C2/c with a = 14.766 (5) Å, b = 10.442 (2) Å, c = 18.696 (3) Å, β = 109.37 (2)°, V = 2720 (2) Å3, Z = 4, T = 248 K, RF = 0.045, RwF = 0.048 on 227 variables and 1631 data; 3, space group C2/c with a = 10.846 (3) Å, b = 19.972 (4) Å, c = 21.435 (4) Å, β = 99.25 (2)°, V = 4583 (4) Å3, Z = 4, T = 248 K, RF = 0.053, RwF = 0.063 on 196 variables and 1109 data.
AB - Alkylation of diethyl ether solutions of MnCl2 with 4 equiv of LiR (R = Me, Et, n-Bu, t-Bu, CH2SiMe3 or Ph) in the presence of N, N, N', N'-tetramethylethylenediamine (tmed) gives pale-colored divalent tetraalkylmanganates of stoichiometry [Li(tmed)]2[MnR4] in good yields. In the case of Li(t-Bu), a side reaction with diethyl ether leads to the formation of ethylene and the eventual isolation of the insertion product [Li(tmed)]2[Mn(CH2CH2-t-Bu)4]; the tert-butyl complex [Li(tmed)]2[Mn(t-Bu)4] could not be prepared even in other solvents. These 13-electron peralkyl species are stable at room temperature and are among the few well-characterized compounds of their type. The alkyls that contain β-hydrogen atoms are remarkably resistant to β-elimination. The single-crystal X-ray structures of [Li(tmed)]2[MnMe4] (1), [Li(tmed)]2[MnEt4] (2), and [Li(tmed)]2[Mn(CH2CH2-t-Bu)4] (3) have been determined, and compounds 2 and 3 are the first structurally characterized transition-metal peralkyls that contain β-hydrogen atoms. The coordination geometries around the manganese centers are essentially tetrahedral, and there are no agostic Mn•••H-C interactions. The Li cations each interact with two a-carbon atoms of the alkyl ligands and bridge opposite edges of the tetrahedron to give nearly linear Li•••Mn•••Li arrays. Crystallographic data (Mo Ka, X = 0.71073 A): 1, space group P21/c with a = 13.591 (2) Å, b = 15.190 (3) Å, c = 12.007 (2) Å, β = 94.27 (1)°, V = 2472 (1) Å3, Z = 4, T = 223 K, RF = 0.062, RwF = 0.068 on 179 variables and 1812 data; 2, space group C2/c with a = 14.766 (5) Å, b = 10.442 (2) Å, c = 18.696 (3) Å, β = 109.37 (2)°, V = 2720 (2) Å3, Z = 4, T = 248 K, RF = 0.045, RwF = 0.048 on 227 variables and 1631 data; 3, space group C2/c with a = 10.846 (3) Å, b = 19.972 (4) Å, c = 21.435 (4) Å, β = 99.25 (2)°, V = 4583 (4) Å3, Z = 4, T = 248 K, RF = 0.053, RwF = 0.063 on 196 variables and 1109 data.
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U2 - 10.1021/om00108a018
DO - 10.1021/om00108a018
M3 - Article
AN - SCOPUS:0000223559
SN - 0276-7333
VL - 8
SP - 1478
EP - 1485
JO - Organometallics
JF - Organometallics
IS - 6
ER -