Crystal structure and molecular packing analysis of 1,5-anhydropentitols and per-O-acetyl derivatives

The crystal structures of three 1,5-anhydropentitols of formulae C5H10O4 and their per-O-acetyl derivatives of formulae C11H16O7 are reported. 1,5-anhydro-D-arabinitol (ADA), 1,5-anhydroribitol (AR), 1,5-anhydroxylitol (AX), 2,3,4-tri-O-acetyl-1,5-anhydro-D-arabinitol (AcADA), 2,3,4-tri-O-acetyl-1,5-anhydroribitol (AcAR) and 2,3,4-tri-O-acetyl-1,5-anhydroxylitol (AcAX) have the following space group and unit cell parameters: ADA, orthorhombic, P212121, a = 6.521(1) Å, b = 6.826(1) Å, c = 13.557(3) Å; AR, monoclinic, P21/n, a = 6.515(1) Å, b = 12.003(1) Å, c = 8.272(1) Å, β = 105.65(1)°; AX, monoclinic, P21/n, a = 6.652(2) Å, b = 9.224(2) Å, c = 10.548(2) Å, β = 101.80(1)°; AcADA, orthorhombic, P212121, a = 8.182(2) Å, = 10.768(2) Å, c = 15.111(3) Å; AcAR, monoclinic, P21/c, a = 15.178(1) Å, b = 10.339(1) Å, c = 8.038(1) Å, β = 92.50(1)°; and AcAX, monoclinic, P21/c, a = 12.092(1) Å, b = 9.066(1) Å, c = 12.492(2) Å, β = 102.39(1)°. The structures were solved using direct methods and refined by full-matrix least-squares techniques to R indices of 0.033, 0.042, 0.045, 0.066, 0.055 and 0.048, respectively. The pyranoid ring adopts 4C1 chair confirmation in the molecules of AR, AX and AcAX, and the 1C4 one in the molecules of ADA, AcADA and AcAR. Theoretical methods were used to examine lattice energetics and molecular packing in the crystals formed.