Table 1.

Calculated threshold energies (in units of eV) of cationic fragments from the reaction Fe(CO)₄(η²-C₄H₆O₂) + e⁻.

m/z	Ion	Neutral fragments	E th
254	Fe(CO)4(η2-C4H6O2)+		7.43
226	Fe(CO)3(κ1-C4H6O2)+	CO	7.96, 8.75
198	Fe(CO)2(κ1-C4H6O2)+	2 × CO	8.62a, 9.33
170	Fe(CO)(η2-C4H6O2)+	3 × CO	10.06a, 11.31
168	Fe(CO)4+	(C4H6O2)	8.91
142	Fe(η4-C4H6O2)+	4 × CO	11.62a
142	Fe(CO)3H2+	(C4H4O2), CO	13.01
140	Fe(CO)3+	(C4H6O2), CO	10.04
127	Fe(CO)2CH3+	(C3H3O2), 2 × CO	13.33
114	(C4H6O2)CO+	Fe(CO)3	11.21
114	Fe(CO)OCH2+	3 × CO, C3H4O	14.90
114	Fe(CO)2H2+	2 × CO, (C4H4O2)	15.22
112	Fe(CO)2+	2 × CO, (C4H6O2)	12.31
86	C4H6O2+	Fe(CO)4	11.07
84	Fe(CO)+	3 × CO, (C4H6O2)	14.20
56	Fe+	4 × CO, (C4H6O2)	15.65

^aThe methyl acrylate ligand is η⁴-bonded such that the carbonyl oxygen interacts with the iron center.