TY - JOUR
T1 - Oxidative stretching of metal-metal bonds to their limits
AU - Brogden, David W.
AU - Turov, Yevgeniya
AU - Nippe, Michael
AU - Li Manni, Giovanni
AU - Hillard, Elizabeth A.
AU - Clérac, Rodolphe
AU - Gagliardi, Laura
AU - Berry, John F.
PY - 2014/5/5
Y1 - 2014/5/5
N2 - Oxidation of quadruply bonded Cr2(dpa)4, Mo 2(dpa)4, MoW(dpa)4, and W2(dpa) 4 (dpa = 2,2′-dipyridylamido) with 2 equiv of silver(I) triflate or ferrocenium triflate results in the formation of the two-electron-oxidized products [Cr2(dpa)4]2+ (1), [Mo2(dpa)4]2+ (2), [MoW(dpa) 4]2+ (3), and [W2(dpa)4] 2+ (4). Additional two-electron oxidation and oxygen atom transfer by m-chloroperoxybenzoic acid results in the formation of the corresponding metal-oxo compounds [Mo2O(dpa)4]2+ (5), [WMoO(dpa)4]2+ (6), and [W2O(dpa) 4]2+ (7), which feature an unusual linear M···M≡O structure. Crystallographic studies of the two-electron-oxidized products 2, 3, and 4, which have the appropriate number of orbitals and electrons to form metal-metal triple bonds, show bond distances much longer (by >0.5 Å) than those in established triply bonded compounds, but these compounds are nonetheless diamagnetic. In contrast, the Cr-Cr bond is completely severed in 1, and the resulting two isolated Cr 3+ magnetic centers couple antiferromagnetically with J/k B= -108(3) K [-75(2) cm-1], as determined by modeling of the temperature dependence of the magnetic susceptibility. Density functional theory (DFT) and multiconfigurational methods (CASSCF/CASPT2) provide support for "stretched" and weak metal-metal triple bonds in 2, 3, and 4. The metal-metal distances in the metal-oxo compounds 5, 6, and 7 are elongated beyond the single-bond covalent radii of the metal atoms. DFT and CASSCF/CASPT2 calculations suggest that the metal atoms have minimal interaction; the electronic structure of these complexes is used to rationalize their multielectron redox reactivity.
AB - Oxidation of quadruply bonded Cr2(dpa)4, Mo 2(dpa)4, MoW(dpa)4, and W2(dpa) 4 (dpa = 2,2′-dipyridylamido) with 2 equiv of silver(I) triflate or ferrocenium triflate results in the formation of the two-electron-oxidized products [Cr2(dpa)4]2+ (1), [Mo2(dpa)4]2+ (2), [MoW(dpa) 4]2+ (3), and [W2(dpa)4] 2+ (4). Additional two-electron oxidation and oxygen atom transfer by m-chloroperoxybenzoic acid results in the formation of the corresponding metal-oxo compounds [Mo2O(dpa)4]2+ (5), [WMoO(dpa)4]2+ (6), and [W2O(dpa) 4]2+ (7), which feature an unusual linear M···M≡O structure. Crystallographic studies of the two-electron-oxidized products 2, 3, and 4, which have the appropriate number of orbitals and electrons to form metal-metal triple bonds, show bond distances much longer (by >0.5 Å) than those in established triply bonded compounds, but these compounds are nonetheless diamagnetic. In contrast, the Cr-Cr bond is completely severed in 1, and the resulting two isolated Cr 3+ magnetic centers couple antiferromagnetically with J/k B= -108(3) K [-75(2) cm-1], as determined by modeling of the temperature dependence of the magnetic susceptibility. Density functional theory (DFT) and multiconfigurational methods (CASSCF/CASPT2) provide support for "stretched" and weak metal-metal triple bonds in 2, 3, and 4. The metal-metal distances in the metal-oxo compounds 5, 6, and 7 are elongated beyond the single-bond covalent radii of the metal atoms. DFT and CASSCF/CASPT2 calculations suggest that the metal atoms have minimal interaction; the electronic structure of these complexes is used to rationalize their multielectron redox reactivity.
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U2 - 10.1021/ic5007204
DO - 10.1021/ic5007204
M3 - Article
C2 - 24746142
AN - SCOPUS:84899842757
SN - 0020-1669
VL - 53
SP - 4777
EP - 4790
JO - Inorganic chemistry
JF - Inorganic chemistry
IS - 9
ER -