Long-Range-¹³C-H-Kopplungen in einigen Cyclobutadien-eisentricarbonylen. Ein Beitrag zur Kenntnis der Bindungsverhältnisse im komplexgebundenen Cyclobutadien

Abstract

All observable long-range 13 C-H-coupling constants have been measured for cyclobutadiene-iron-tricarbonyl, 1.2-dimethyl-cyclobutadiene-irontricarbonyl, trimethyl-cyclobutadiene-irontricarbonyl and tetramethyl-cyclobutadiene-irontricarbonyl. The couplings are assigned and discussed with respect to bonding problems in the four-membered ring. A quadratic structure of the cyclobutadiene-system with uniform C—C-bond order is postulated on the basis of these measurements.