Trimipraminium maleate

The title compound systematic name: 3-(10,11-dihydro-5{\it H}-dibenzo\it b,\it f]azepin-5-yl)-\it N,\it N,2-trimethyl\-propan-1-aminium hydrogen maleate], C\sb 20H\sb 27N\sb 2\sp +⋅C\sb 4H\sb 3O\sb 4\sp -}}, a maleate salt of trimipramine, crystallizes with four independent cation—anion pairs in the asymmetric unit. The trimipramine cation contains a seven-membered azepine ring with two fused benzene rings whose mean planes are separated by 51.7(1)\circ. Inter\-molecular N—-H⋅sO and intra\-molecular O—-H⋅sO hydrogen bonds pack the ions into chains along 101. Additional weak inter{\-}molecular C{---}H{$\cdots$}O inter{\-}actions help to influence the twist angles of the mean planes of the benzene rings fused to the azepine ring in the cation. A geometry-optimized MOPAC AM1 theoretical calculation supports these observations