The preparation of highly diastereo- and enantiomerically enriched planar chiral 1-phenylsulfonyl-substituted tricarbonyl( η 5-pentadienyl)iron(1 +) complexes 7 [ syn,syn-(1 R,5 R)- 7 and syn,syn-(1 S,5 S)- 7 ( cisoid- or U-forms); de > 99% 5- syn-CH 3/5- anti-CH 3 ⪢ 100:1, ee > 99%; 87% quant. from resolved 6] is described. Starting from the enantiopure diene (1 E,3 E,S)- 5 both enantiomers of the cationic complexes syn,syn- 7 become readily accessible via chromatographic resolution of the diastereomeric mixture of the corresponding neutral tricarbonyl( η 4-diene)iron(0) complexes 6 [(1 R,5 S)- 6 ψ- endo- 6 and (1 S,5 S)- 6 ψ- exo- 6; de > 99%, ee > 99%; 85% quant. prior to resolution]. The nucleophilic addition of hetero and carbon atom nucleophiles (morpholine, silyl enol ether 8 and silyl ketene acetal 9) to the racemic complex syn,syn-( 1 R/S, 5 R/S)- 7 afforded the neutral ε-substituted tricarbonyl( η 4-diene)iron(0) complexes rac-ψ- exo- 10ac in moderate yields [43–68% from syn,syn-(1 R/S,5 R/S)- 7] as single geometrical isomers [( E,Z) or ( E,E); kinetic ( U-form/strong nucleophile) or thermodynamic ( S-form/less reactive nucleophile) control]. Likewise, nucleophilic addition to the stereochemically homogeneous complexes syn,syn-(1 R,5 R)- 7 or syn,syn-(1 S,5 S)- 7 followed by oxidative cleavage of the carbonyl-iron fragment offers an access to ε-substituted dienes 11a-c in moderate to fair yields [45–65%, ( E,Z)/( E,E) = > 85:1-1:3] with enantiomeric excesses ranging from > 99%/98.9% [(1 E,3 Z,R)- 11a/(1 E,3 Z,S)- 11a] to 93% [(6 E,8 E,S)- 11b]. The stereochemistry of the formation and the stereochemical pathways of the nucleophilic addition reactions of the nonracemic complexes syn,syn- 7 leading to the dienes 11a-c as well as spectroscopic and structural details are discussed. Furthermore, the reaction proceeds with virtually complete “chirality transfer” from CO via CFe to CN or CC, respectively, with either retention or inversion of stereochemistry of the stereogenic centre with respect to the starting material ( S)- 1 depending strongly on the reaction conditions. The observed ε-regioselectivity of the nucleophilic addition reaction displays the synthetic equivalence of the cationic complexes of type syn,syn- 7 with a planar chiral a 6-synthon allowing an umpolung of the classical d 6-chemistry.