Ligand structures dinitrogen complexes

Fig. 8. Mo/W dinitrogen complex with the P/N ligand N,N,N, N -tetrakis-(diphenylphosphinomethyl)-2,6-diaminopyridine (pyN2P

Relevant bond distances and angles of dinitrogen complexes whose X-ray structure has been determined are shown in Table 15. The complex [ Ni(PCy3)2 2N2] (Figure 1) is dimeric, with the N2 molecule coordinated end-on to the two nickel atoms. Each nickel atom is surrounded by four cyclohexyl groups of the phosphine ligands which give some steric protection.227 IR, 31P and HNMR spectra indicate that in toluene solutions of this complex the equilibrium shown in equation (60) operates.236... 

Hydrazido(2 —) complexes are most prevalent within group VI although there are to date no reported hydrazido complexes of chromium. Representative examples of known structure are shown in Table 16. Sulfur coligands predominate reflecting the metal-sulfur coordination in nitrogenase and the participation of hydrazide ligands in dinitrogen chemistry. 

Other complexes whose crystal structures have been determined include the tetraphosphorus complex (21),191 and the dinitrogen complex (22).182 The latter complex was originally believed to contain a sideways-on dinitrogen ligand 183 however, once corrections were made for disorder and anisotropy of the dinitrogen ligand, the more usual end-on coordination was proposed.182... 

Figure 2. Typical structures of dinitrogen complexes with transition metal compounds (M = metal -I- other ligands).

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