[Dolphinsiu]

Why [Co(CN)6]3- has larger Racah parameter B than [Co(H2O)6]3+?

I only know that the former has low spin d6 coordination system whereas the latter has high spin d6 coordination system. The bond length is shorter for the former. Is this related to electron-electron repulsion? I have heard that free electron has high energy whereas bond electron has less energy due to electron delocalization.