Resonance structures metal butadiene complex

As shown in the structure [4-11], a butadiene-metal Tc-complex also contains three types of protons. The relative resonance intensities, however, are 1 1 1. The resonance signal at 4-5 t is attributed to the protons. The signals for and are again found at a higher field— near 9t. Several examples of diolefin complexes are given in Table 4-22. 

In the reduction of acetylene with molybdothiol and molybdoselenol complex catalysts, the effects of structural variation in ligands, variety of coordination-donor atom, kind of transition-metal ion, and other factors have been surveyed systematically. These factors have profound effects on the catalytic activity. The Mo complexes of cysteamine (or selenocysteamine), its N,N-dimethyl derivative, and its /3-dimethyl derivative give ethylene, ethane, and 1,3-butadiene, respectively, as the major product. The Co (I I) complexes of cysteine and cysteamine show higher catalytic activity than do the corresponding Mo complexes, and the order of the activity in the donor atom, namely S >Se 0 in the Co(II) complexes is consistent with that in the Mo complex systems. On the basis of electron spin resonance (ESR) features of these Mo complex catalysts, a relationship between their ESR characteristics and catalytic activities is discussed. 

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