Monohalogenated ferrocenes C₅H₅FeC₅H₄X(X= Cl, Br and I) and a second polymorph of C₅H₅FeC₅H₄I

Radial (tetracyclopentadienyl)cyclobutadiene pentametals

“…For comparative purposes (vide infra), the CpCo analog of 4, complex 11, was made by cyclodimerization of alkyne 10 [25,26] according to Scheme 5 and in analogy to the preparation of CpCo(tetraferrocenylcyclobutadiene) [3].…”

Coordination chemistry of perhalogenated cyclopentadienes and alkynes. Part 30. New high-yield syntheses of monochloroferrocene and 1,2,3,4,5-pentachloroferrocene. Molecular structures of 1,2-dichloroferrocene and 1,2,3-trichloroferrocene

“…The bonds from Fe to the chlorine bearing C atoms are slightly shorter than to the other carbon atoms of the substituted cyclopentadienyl ring (2.017(2) Å vs. 2.037 Å in 2 and 2.014(2) vs. 2.046(2) Å in 4). The substituted rings are closer to the metal than the unsubstituted ones, and that the distance difference increases with increasing number of chlorine substituents: FeeCt (C 5 H 5Àn Cl n ) ¼ 1.646(12) Å (n ¼ 1 [8]), 1.6335(10) Å (n ¼ 2), 1.6276(10) Å (n ¼ 3) and FeeCt (C 5 H 5 ) ¼ 1.653(12) Å (n ¼ 1), 1.6509(11) Å (n ¼ 2), 1.6546(15) Å (n ¼ 3) ("Ct" denotes the centroid of the cyclopentadienyl ring). The chlorine atoms are slightly shifted out of the plane of the cyclopentadienyl ring to the distal side of the Fe atom (av.…”

Polar Metallocenes

“…This is consistent with the weaker electronegativity of Si relative to C. When we replaced one H atom by F, we found more electrons on the -C 5 H 4 F − ring than on the Cp side, consistent with the stronger electronegativity of F with respect to H. Therefore, Fe(C 10 H 9 F) has a large dipole moment (1.70 D), pointing away from the unsubstituted Cp ring. Experimentally, metallocenes with 1–5 halogens per ring have been synthesized [10,34,35,36,37,38,39]. When we replaced F with heavier halogens, we found that the dipole moment increased to 1.77, 1.82, and 1.81 D in Fe(C 10 H 9 Cl), Fe(C 10 H 9 Br), and Fe(C 10 H 9 I), respectively (Table 3).…”