Structural studies of organometallic compounds. I. The crystal and molecular structures of (β,α,1,6-tetrahapto:2,3,4,5-tetrahapto-3,α-dimethylstyrene)bis(tricarbonyliron) and 4,5,6,7-tetrahapto-[(2,3,9,8-tetrahapto-1,1',1''-tricarbonyl-1-ferraindene)tricarbonyliron(Fe–Fe)]tricarbonyliron

Structural studies of organometallic compounds. II. The crystal and molecular structure of 1',1'',1''',1''''-Tetracarbonyl-3,4-dicyclopropyl-1-ferracyclopent-3-ene-2,5-dione

“…The mean Fe-C(sp 2) length is about 2.04/~, while Fe-C(sp 3) is about 0.07 A longer, which is nearly the difference between the radii of C in these two valence states (0-77 -0.67 = 0.10 A). The mean Fe--O(carbonyl) distance is 2.96 A, slightly larger than that found for carbonyls bound to Fe in (CO)3Fe-(cis-butadiene) moieties (2.93 A, Herbstein & Reisner, 1977); the mean Fe-C-(carbonyl) distance is 1.825 A, about 0.04 A longer than that (1.788 A) found in tricarbonylferracyclopentadiene moieties. Similarly Fe-C(sp 2) is about 0.08 ,A longer than the average for analogous bond lengths in ferracyclopentadiene rings.…”

“…In this regard they differ from the ferracyclopentadiene rings of the binuclear tricarbonyliron (tricarbonylferracyclopentadiene) compounds discussed by Herbstein & Reisner (1977) in which the Fe atom deviates by ~0.2 A from the plane of the four C atoms. …”