硫酸三(2,2'-联吡啶)合铬(11)电子光谱的讨论

STUDY ON THE ELECTRON SPECTRA OF TRIS(2,2'-BIPYRIDINE) CHROMIUM(11)

[C(r2,2'-bpY)_3]so_4的电子光谱有四个吸收峰,λ_1=486.4nm,λ_2=393.4nm,λ_3=306nm,λ_4=242nm.λ_1和λ_2都是d→d光谱,分别是电子从~3T_1g(P)跃迁到~3Eg和~3T_2g而产生的。λ_3和λ_4都是配体光谱,λ_3属于n→π*跃迁,入_4属于π→π*跃迁。场强参数D_q值为2225cm^(-1),大约是六水合铬(11)的D_q值的1.4～1.76倍。电子排斥参数B值约770cm^(-1),电子云扩展系数β≤0.93。配体与中心离子之间只形成很弱的σ键,而无授受(π)键。

The four absorpton bands of Cr(bpy)_3^(2+) are observed irt the visible and UV region. λ_1=486, 4nm, λ_2=393.4nm. which belong to the d-d spectra. λ_1 is ~3T_(1g)(P)→~3E_g and λ_2 is ~3T_(1g)(P)→~3T_(2g) transition. λ_3=306nm, λ_4=242nm. They are both ligand spectra. The first absorption band of UV is the electrontransfer from unbonding MO(n) to the antibonding MO(π~*). The second isπ→π~* transition.on the basis of the d-d spectra in Cr(bpy)_3^(2+), the values of D_q and Racah par-ameter B is calculated to be 2225cm^(-1) and 770c^(-1), respectively. β(?)0.90, the σ bonding between the Cr(11)-N is weakly, the π bonding has notbeen formed in the complex.