Crystal Structures of Ergot Alkaloid Derivatives. Ergometrine Maleate and Methylergometrine Maleate

Two ergot alkaloid derivatives were examined by X-ray diffraction techniques. The crystal and molecular structure of ergometrine maleate ( 1 ) was evaluated from single-crystal data and the molecular structure of related methylergometrine maleate ( 2 ) was obtained by molecular modelling. The measured and calculated X-ray powder patterns of 1 and 2 were compared. Derivative 1 crystallizes in the orthorhombic space group P2 1 2 1 2 1 with a = 5.7112(7) Å, b = 12.337(2) Å, c = 33.276(6) Å, Z = 4, V = 2 344.5(6) Å 3 . Derivative 2 is nearly isostructural with 1 , it has slightly expanded unit cell, a = 5.724(2) Å, b = 12.762(6) Å, c = 33.25(2) Å, Z = 4, V = 2 428(1) Å 3 . No effect of an additional methyl group on the molecular packing of 2 was found.