Ferrole-estradiol complex as a test for receptor dimerization

We describe the synthesis of a structure based on the iron carbonyl mediated head-to-head coupling of two molecules of 17α-ethynylestradiol that leads ultimately to a ferrole. This compound was prepared with the aim of probing the mechanism of action of the estradiol receptor; spectroscopic, molecular modelling and biochemical studies are reported. The estradiol-ferrole cluster retains a weak, but not zero, affinity for the estradiol receptor. There is reversible binding to the receptor, and this is rationalized in terms of the pKR+ value of −13.1 found for the bioorganometallic complex.