Fig. 2. Proposed structure for the isomers in solution 5a, 5b, 6a and 6b. (a) ROE cross peaks between Cp-H (5a/5b: 5.25 ppm) and H^1a (5a: 3.03 ppm; 5b: 3.08 ppm) and H³ (5a: 2.94 ppm; 5b: 2.88 ppm); and ROE cross peaks between H⁵ (5a: 5.89 ppm) and H³ (5a: 2.94 ppm) and H² (5a: 2.68 ppm), and between H⁵ (5b: 5.88 ppm) and H^1a (5b: 3.08 ppm) and H³ (5b: 2.88 ppm). (b) ROE cross peaks between Cp-H (6a/6b: 5.56/5.57 ppm, respectively) and H^1a (6a: 3.29 ppm; 6b: 3.22 ppm) and H³ (6a: 2.99 ppm; 6b: 2.96 ppm).