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Crystal and Molecular Structure of Tricarbonyl‐[(1 R *, 4 S *, 4a S *, 9a R *)‐1,4‐epoxy‐2, 3‐dimethylidene‐1,2,3,4,4a,9,9a,10‐octahydroanthracene]iron
Author(s) -
Alini Mauro,
Roulet Raymond,
Chapuis Gervais
Publication year - 1983
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19830660532
Subject(s) - chemistry , tetragonal crystal system , crystallography , crystal structure , stereochemistry , dihedral angle , group (periodic table) , metal , single crystal , crystal (programming language) , molecule , organic chemistry , hydrogen bond , computer science , programming language
The thermal cyclodimerization of 5,6‐dimethylidene‐7‐oxabicyclo[2.2.1]hept‐2‐ene assisted by Fe 2 (CO) 9 gives the title complex 1 , a precursor for the synthesis of antitumoral anthracyclinones. The crystal structure of 1 has been determined by X‐ray diffraction: a = 11.188 (1); c = 26.968 (3) Å; space group tetragonal, P 4 1 2 1 2, Z = 8; R = 0.041; R W = 0.033. The tricarbonyliron group is in the exo ‐position and the coordination polyhedron is tetragonal pyramidal. The NMR coupling constants are well‐related to the observed dihedral angles between the non‐aromatic protons and now give a reliable criterion for assigning the stereochemistry of the metal in d 8 ‐complexes of 2,3‐dimethylidene‐7‐oxanorbornane derivatives.