Table 1 Geometric and electronic structure data of [{IMesCo}2Bi5] (1) and hypothetical anion [{IMesCo}2Bi5]− obtained with the functional PBE

From: Isolation of a planar π-aromatic Bi5− ring in a cobalt-based inverse-sandwich-type complex

 

Co–Co

Co–Bi

Bi–Bi

C–Co–Co

E

S2 (S2–S[S + 1])

g

Gap

Nue (Co/Co/Bi5)

X-ray

2.52

2.75–2.79

2.90–2.91

176

–

–

 

–

–

M−

2.53

2.72–2.83

2.91–2.93

176

 

0

 

1.235

0.0/0.0/0.0

2A

2.56

2.70–2.88

2.90–2.96

170

0

0.811 (0.061)

2.03

0.254

0.49/0.49/0.03

2B

2.57

2.72–2.85

2.89–2.92

179

0

0.764 (0.014)

2.03

0.169

0.44/0.44/0.19

2BS

2.53

2.67–2.86

2.90–2.94

178/169

–3

0.830 (0.083)

2.05

0.331

1.20/–0.19/0.04

4A

2.65

2.76–2.95

2.93–2.94

167

+46

3.887 (0.137)

1.93

0.057

1.51/1.51/0.05

  1. Column labelling: Co–Co, Co–Bi and Bi–Bi are the (ranges of) distances (in Å) between the corresponding atoms, C–Co–Co labels the bend of the Co–Co axis and the Co–C axes at the two Co atoms (in °). E is the energy relative to the 2A state (in kJ mol−1); in the following column, the S2 values and their deviations from the value for the pure doublet/quartet are given, g is the calculated g factor, Gap denotes the HOMO–LUMO gap (in eV) and Nue is the number of unpaired electrons according to a Mulliken analysis75 at the Co atoms and at the {Bi5} ring. Row labelling: M− denotes the anionic (diamagnetic) species. The subsequent lines denote neutral species: in 2A, the orbital 126a (HOMO within the irrep a) is singly occupied, in 2B, the orbital 123b (HOMO within irrep b) is singly occupied. 2BS is a broken symmetry state with overall one unpaired electron. In 4A the unpaired electrons reside in 126a, 123b and 124b (Fig. 5).
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