1,8-Bis(dimethylamino)-2-(4-methoxyphenyl)naphthalene: An electrospray-active analogue for η6-coordinating ligands

1,8-Bis(dimethylamino)-2-(4-methoxyphenyl)naphthalene (1) was synthesized for use as an eta(6)-coordinating ligand with a chargeable tag for ESI-MS analysis. The pK(a) of the proton sponge moiety was essentially unaffected by addition of the anisole group (pK(a) = 18.2 +/- 0.7 at 297 K in CD3CN). Cr(eta(6)-1)(CO)(3) (2) was prepared to demonstrate the utility of (1) as an ESI tag and 2 was easily visible by ESI(+)-MS. A single crystal structure of the complex showed eta(6)-binding of the ligand as expected with the charged moiety being far removed from the metal centre. The gas-phase reactivity of 2 was found to match that of the analogous uncharged chromium carbonyl complex Cr(C6H5OCH3)(CO)(3) indicating that 1 has potential as a chargeable tag for the study of organometallic complexes and their reactions by ESI-MS. (C) 2012 Elsevier B. V. All rights reserved.