Butterfly Diradical Intermediates in Photochemical Reactions of Fe₂(CO)₆(μ-S₂)

Abstract

Photolysis of the tetrahedrane Fe2(CO)6(mu-S2) at 450 +/- 35 nm in a Nujol matrix at low temperatures gives an isomer characterized by its nu(CO) infrared frequencies. Comparison of these experimental frequencies with those calculated by density functional theory using the BP86 functional indicates this photoisomer to be the butterfly singlet diradical Fe2(CO)6S2 isomer in which the S-S bond of the tetrahedrane is broken but the Fe-Fe bond is retained. Photolysis at higher energies (420-280 nm) results in CO loss from this singlet butterfly diradical as indicated again by comparison of the experimental infrared nu(CO) frequencies with those calculated for an Fe2(CO)5S2 isomer of this type.

Binuclear Carbonylheptalenechromium Complexes: Partition of Heptalene into a Complexed Heptafulvene Subunit and an Uncomplexed 1,3‐Diene Subunit for Coordination to a Multiply Bonded Pair of Chromium Atoms

“…The reported ν(CO) frequencies are those determined by the BP86 method, which has been shown to be more reliable than the B3LYP method for this purpose. [40] In this work, the reported ν(CO) frequencies predicted by the BP86 method are also found to be closer to the experimental values than those determined by the M06L method.…”

Formal chromium–chromium triple bonds and bent rings in the binuclear cycloheptatrienylchromium carbonyls (C7H7)2Cr2(CO)n (n=6,5,4,3,2,1,0): A density functional theory study

“…The other (C 7 H 7 ) 2 Cr 2 (CO) n derivatives (n = 4, 3, 2, 1) are seen to be energetically favored with respect to disproportionation. Table 16 summarizes the m(CO) frequencies of the (C 7 H 7 ) 2 Cr 2 (CO) n derivatives using the BP86 functional, which has been found to be more reliable for m(CO) frequencies than the B3LYP method [47,48]. As expected, the bridging m(CO) frequencies appear $300 cm À1 below the terminal m(CO) frequencies in similar compounds and thus typically around 1600 cm À1 .…”

Cyclic versus acyclic structures of six-carbon ligands in binuclear cobalt carbonyl derivatives: Some thermochemical observations

“…The second approach is the BP86 method, which combines Becke's 1988 exchange functional with Perdew's 1986 correlation functional [23,24]. The BP86 method usually provides vibrational frequencies closer to the experimental values [25]. However, Reiher and coworkers have found that B3LYP favors the high-spin state and BP86 favors the low-spin state [26].…”