Preparation and characterisation of 9,10‐dihydroanthracene and tert‐butyl‐9,10‐dihydroanthracene complexes with one or two tricarbonylchromium units; crystal structure of tricarbonyl (η^{1,2,3,4,4a,9a}‐9,10‐dihydroanthracene)chromium

The complexes [9,10‐dihydroanthracene][tricarbonylchromium]_n [9,10‐DHA][Cr(CO)₃]_n [n = 1 (1), 2 (2)] and the related mono‐ and bis(tricarbonylchromium) complexes of 2,6‐ and 2,7‐di‐tert‐butyl‐9,10‐dihydroanthrancene [2,6‐DB‐9,10‐DHA][Cr(CO)₃]_n [n = 1 (3), 2 (4)] and [2,7‐DB‐9,10‐DHA][Cr(CO)₃]_n [n = 1 (5), 2 (6)] have been prepared by heating the 9,10‐DHA species in the presence of hexacarbonylchromium [Cr(CO)₆]. Evidence for the existence of the complex [2,6,9‐tri‐tert‐butyl‐9,10‐DHA][Cr(CO)₃] (7) is also presented. The complexes have been characterised spectroscopically, and for complex 1 an X‐ray crystallographic structure determination has been carried out. This complex adopts the unexpected structure in which the non‐coordinated arene ring is bent towards the Cr(CO)₃ moiety. The syntheses and spectroscopic characterisations of 2,6‐ and 2,7‐di‐tert‐butylanthracene (2,6‐ and 2,7‐DBA), 2,6‐ and 2,7‐di‐tert‐butyl‐9,10‐dihydroanthracene (2,6‐and 2,7‐DB‐9,10‐DHA), 2,6,9‐, 2,7,9‐, and 2,7,10‐tri‐tert‐butyl‐9,10‐dihydroanthracene (2,6,9‐, 2,7,9‐ and 2,7,10‐TB‐9,10‐DHA), and 2,6,9,10‐ and 2,7,9,10‐tetra‐tert‐butyl‐9,10‐dihydroanthracene(2,6,9,10‐ and 2,7,9,10‐TeB‐9,10‐DHA) are also given.