2,4-Dimethyl-3-phenyl-[2'-methyl-3'-chloro]-7-chloro-8-methyl-1,3-diaza-2,4-diboranaphtalene Tricarbonylchromium Complexes

All reactions were carried out under dry nitrogen using Schlenk techniques. 2,4–Dimethyl-3-phenyl-[2’-methyl-3’-chloro]-7-chloro-8-methyl-1,3-diaza-2,4-diboranaphtalene tricarbonylchromium complexes were obtained by a classical method [1]. A solution of ligand (0.3 g, 0.907 mmol) and Cr(CO)₆ (0.3 g, 1.36 mmol) in 30 mL of dibutyl ether and 5 mL of THF was heated under reflux for 48 h under vigorous stirring. A strong yellow color shows the formation of the complex. After cooling and filtration through silica gel, the solution was evaporated to dryness. The crude product is a mixture of two isomers (0.19 g, 45%, Mp: 165°C). Reaction with Cr(CO)₃ gives exclusively the compounds with Cr(CO)₃ h⁶-bonded to the benzo part of the molecule [2]. The two isomers were separated by silica gel chromatography with diethyl ether/hexane mixture (25/75).

Isomer 1, Mp:180-182°C; isomer 2, Mp:176-178 °C.

¹H (500 MHz) and ¹³C NMR (125 MHz) chemical shifts for isomer 1 and isomer 2