X-Ray crystallographic and NMR evidence for a uniquely strong OH ⋯ N hydrogen bond in the solid state and solution

Crystallographic and NMR evidence indicates that the neutral compound (1) has a strong and essentially linear [170(1)°] O–H ⋯ N intramolecular hydrogen bond as part of a seven membered ring, with uniquely short O ⋯ N and H ⋯ N distances of 2.465(5) and 1.32(2)A and an O–H distance of 1.16(2)A respectively.