| abstract |
In the formula, R1 represents a linear or branched alkyl group having 2 to 4 carbon atoms; R2 to R5 each independently represent a linear or branched alkyl group having 1 to 4 carbon atoms; A represents an alkanediyl group having 1 to 4 carbon atoms; and M represents titanium, zirconium or hafnium. Provided that when M represents zirconium, A represents an alkanediyl group having 3 or 4 carbon atoms. When M represents titanium or hafnium, it is preferred that A represents an alkanediyl group having 2 or 3 carbon atoms. When M represents zirconium, it is preferred that A represent an alkanediyl group having 3 carbon atoms. |