Scorpionate Coordination Mode

Tris(pyrazolyl)borates, Tpx, generally coordinate as tridentate k3-N, N, iV -ligands through three nitrogen atoms of the pyrazole rings (Fig. 1.11(a)), providing effective steric shielding of the metal center. Besides the very common k3-N,N, -coordination mode, the tridentate k3-N,N, B-H type (Fig. 1.11(b)),18 the bidentate k2-N,N (Fig. 1.11(c))44 and k2-N,B—H coordination (Fig. 1.11(d))45,46 have been also reported. In contrast to the relatively easy formation of 

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Co(Bpph2) (pz )Bpph2 ]. 2C6H14 (Fig. 4.11) have been reported. The scorpionate ligands are coordinated in the classical k3-coordination mode in all complexes. In the nitrate derivative, the coordination sphere is completed by three oxygen donor atoms from NO3 and THF whereas in the heteroleptic complex, Bpph2 acts as a k3-A 2, H-donor.64... 

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