Titanium complexes pseudohalides

As discussed in Sec. 111-15, the mode of coordination of the pseudohalide ion can be determined by vibrational spectroscopy. Burmeister et al. " found that all NCS and NCSe groups are N-bonded in M(Cp) X2-type compounds, where M is Ti, Zr, Hf, or V, and X is NCS or NCSe. In the case of analogous NCO complexes, Ti, Zr, and Hf form O-bonded complexes, whereas V forms an N-bonded complex. Later, Jensen et al suggested the N-bonded structure for the titanium complex. 

Comparison of the titanium-pseudohalide complexes (86) and (88) shows nicely the different bonding of the pseudohalide, i.e. bent Ti—N—N vs. linear Ti—N—C of the N-bonded isocyanate and isothiocyanate. Table 9a shows that in isostructural M(tj5-Cp)2(NCO>2 (M = Ti, Zr)222 the N—C (b) bonds tend to be shorter than the C—O (c) bonds. This may point to a larger contribution of canonical structure (89) which has some C—O triple bond character in the bonding. 

TV-phenylbenzohydroxamic acid, 506, phthalocyanines, 865 polypyrazolylborates, 248 porphyrins, 823 pseudohalides, 228 Titanium(III) complexes octaethylporphyrin reaction with dioxygen, 325 Titanium(IV) complexes 1,3-diketones, 376 triazines... 

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