Electron spin resonance of bis(1-phenylborabenzene)cobalt(II)

Abstract

Electron spin resonance measurements of bis(1-phenylborabenzene)cobalt(II) in toluene–ether solution at 77 K yields the following parameters: g_x= 2·130, g_y= 1·915, g_z= 1·990, A_x= 142. A_y= 62, A_z= 34 (× 10^–4 cm^–1), and |Q′|= 0·0003 cm^–1. The sign of Q′ is deduced to be positive. The nominal electron configuration is (d_x²–y²)², (d_xy)², (d_yz)², (d_z²)¹. The unpaired electron is in a d_z²–d_x²–y² hybrid orbital with 66% in d_z² and 13% in d_x²–y². Analysis of the quadrupole coupling constant suggests that the bonding is very similar to that in ferrocene with 0·7 electron back donated to each borabenzene ring.