Table 2. Comparison of important bond parameters (Å, °) of compounds 1–4 and some related structures from the CSD.
| 1 | 2 | 3 | 4 | SIRMIP | MARFET | MARFIX | PUYDES | HOZWIC | CECKUS01 | |
|---|---|---|---|---|---|---|---|---|---|---|
| Fe—Ct (Å) | 1.7403 (8) | 1.7625 (10) | 1.7586 (7) | 1.7603 (7) | 1.738 (5) | 1.7464 (10) | 1.7360 (12)/ | 1.715 (3) | 1.730 | 1.730 |
| 1.7306 (12) | ||||||||||
| Fe—Cα(R) (Å) | 2.073 (2) | 2.022 (2) | 2.1188 (17) | 2.0810 (16) | n.a. | n.a. | n.a. | n.a. | 2.069 (10) | 2.002 (2) |
| Fe—C(CO) (Å) | 1.751 (2) | 1.755 (2) | 1.745 (2) | 1.755 (2) | 1.812 (5) | 1.803 (3) | 1.714 (6) | 1.739 (11) | 1.756 (1) | |
| 1.754 (2) | 1.760 (2) | 1.756 (2) | 1.755 (2) | 1.786 (5) | 1.813 (3) | 1.715 (6) | 1.751 (11) | |||
| C—O (Å) | 1.149 (2) | 1.152 (3) | 1.145 (3) | 1.150 (1) | 1.052 (6) | 1.133 (3) | 1.131 (4)/ | 1.182 (7) | 1.153 (13) | 1.151 (2) |
| 1.136 (2) | 1.148 (3) | 1.148 (2) | 1.148 (2) | 1.097 (6) | 1.137 (4) | 1.126 (4) | 1.187 (7) | 1.139 (14) | 1.151 (2) | |
| 1.137 (3)/ | ||||||||||
| 1.132 (4) | ||||||||||
| IR (νCO, cm−1) | 1993, 1941 | 2009, 1968 | 1991, 1939 | 1993, 1939 | 2033, 1993* | 1872, 1806* | 1987, 1933* | 1994, 1937* | ||
| (C i,Ph—Cp)av (Å) | 0.122 | 0.188 | 0.144 | 0.160 | 0.15 | 0.147 | 0.144/0.145 | n.a. | n.a. | |
| (Cp–Ph)av (°) | 50.3 | 48.5 | 50.6 | 50.2 | 58.7 | 52.3 | 51.8/51.4 | 53.4 | n.a. | n.a. |
| [Cα—Fe—Ct—CCp]min | 9.35 | 26.46 | 5.13 | 32.19 | n.a. | n.a. | n.a. | n.a. | 1.44 | 0.0 |
| Ct—Fe—Cα—Cβ (°) | n.a. | 95.8 | 141.1 | 167.4 | n.a. | n.a. | n.a. | n.a. | 179.9 | 87.5 |
| 79.8 | 91.8 |
CSD refcodes: SIRMIP is [(C5Ph5)Fe(CO)2Br] (Field et al., 1989 ▸), MARFET is [(C5Ph5)Fe(CO)2FBF3] (Hemming et al., 2018 ▸), MARFIX is [(C5Ph5)Fe(CO)2(H2O)]BF4 (Hemming et al., 2018 ▸), PUYDES is [PPN][(C5Ph5)Fe(CO)2] (Carter et al., 2002 ▸), HOZWIC is [(C5Me5)Fe(CO)2C5H11] (Hill et al., 1999 ▸) and CECKUS01 is [(C5Me5)Fe(CO)2Ph] (Kalman et al., 2013 ▸). Notes: Ct is the centroid of the cyclopentadienyl ring. (C i,Ph—Cp)av is the average distance of the phenyl ipso-C atoms from the plane of the Cp ring. (Cp–Ph)av is the average dihedral angle of the five phenyl rings with respect to the plane of the Cp ring, [Cα—Fe—Ct—CCp]min is the smallest torsion angle between the α-alkyl/aryl C atom, the Fe atom, the centroid of the cyclopentadienyl ring and a Cp-ring C atom. ‘n.a.’ denotes not applicable. The asterisk (*) denotes solution spectra.