Electronic Structure of Mono‐ and Bis(carbonyliron) as well as Bis(cyclopentadienyliron) Complexes of 1,4‐Dihydro‐1,4‐diboranaphthalene

The structure and bonding of four iron complexes involving the 1,4‐dihydro‐1,4‐diboranaphthalene ligand C 8 B 2 H 8 ( 1 ), namely of the complexes (CO) 3 Fe(η 6 ‐C 8 B 2 H 8 ) ( 2 ), (μ, η 4 ,η 6 ‐C 8 B 2 H 8 )[Fe(CO) 3 ] 2 ( 3 ), (CO) 3 Fe(μ,η 4 ,η 6 ‐C 8 B 2 H 8 )Fe(CO) 2 ( 4 ), and of the triple‐decker (μ,η 6 ‐C 8 B 2 H 8 )[Fe(η 5 ‐C 5 H 5 )] 2 ( 5 ), have been investigated by means of the perturbational molecular orbital theory on the basis of the Extended Hückel calculations. Compounds 2 and 3 are 18‐VE complexes, whereas 5 is a 30‐VE species. The structure of 4 can be best described in terms of a 16‐VE complex “Fe(CO) 3 heterocycle” and a 18‐VE “Fe(CO) 2 carbocycle” unit with its iron centers being not directly bond.