The origin of the crystallographic pedigree

Abstract

The origin of the crystallographic pedigree [Haisa (1978). Acta Cryst. A34, 753-759] by the balance of the interactions between the neighbors of atomic contents which can be estimated from the lifting of the degeneracy of the nearest-neighbor distances, or the coordination index. When the interactions become out of balance, a descent of the space group through Pm3m, Im3m and P63/mmc to their subgroups occurs to form the crystallographic pedigree.

Charge density and electrostatic potential analyses in paracetamol

“…In our study, the structure of paracetamol was solved by direct methods using SHELXS97 (Sheldrick, 2008) in space group P2 1 /n (Nichols & Frampton, 1998) and refined in the spherical-atom approximation (based on F 2 ) using SHELXL97 (Sheldrick, 2008) as included in the WinGX package of programs (Farrugia, 1999). The crystal structure of paracetamol was first reported in the space group P2 1 /a (Haisa et al, 1976). This also holds true for the recent study reporting the variation of cell parameters of paracetamol from 30 to 330 K using neutron diffraction (Wilson, 2000).…”

“…In the solid state, paracetamol exhibits two phases, the monoclinic form I (Haisa et al, 1976) and the orthorhombic form II (Nichols & Frampton, 1998). Solvates and hydrates of paracetamol have also been reported in the literature (Di Martino et al, 1997;McGregor et al, 2002;Parkin et al, 2002).…”

3′-Methylacetanilide andN-benzylthioacetamide at low temperature

“…This relative shift is larger than 5% and is characteristic of a medium-strength hydrogen bond (Desiraju & Steiner, 1999). The N-HÁ Á ÁO hydrogen bond has an NÁ Á ÁO distance of 2.8882 (12) Å , shorter than the values of 2.935 (3), 3.088 (4) and 2.904 (8) Å found in acetanilide (Johnson et al, 1995), p-aminoacetanilide (Haisa et al, 1977) and 4 0 -methylacetanilide (Haisa et al, 1977), respectively. The N-HÁ Á ÁO angle of (I) is almost linear, as is also the case in acetanilide [172.3 (4) ; Johnson et al, 1995].…”

“…The deviations from planarity are smaller than 3 (Galabov et al, 2003). The length of the C8 O1 bond [1.2312 (13) Å ] is very similar to that of the corresponding bond [1.230 (9) Å ] in the analogous compound 4 0 -methylacetanilide (Haisa et al, 1977) and these values are both different from bonds of this type [average value 1.224 (1) Å ; Allen et al, 1997]. The elongation of the C O bond lengths is connected with electron shift accompanying formation of an intermolecular N-HÁ Á ÁO hydrogen bond.…”

“…The length of the C8-N1 single bond [1.3568 (13) Å ] is typical for bonds of this type [average value 1.351 (1) Å ; Allen et al, 1997]. The C-N bond length differs slightly from the values found in similar structures, for example, p-aminoacetanilide [1.344 (4) Å ; Haisa et al, 1977], 4 0 -methylacetanilide [1.349 (3) Å ; Haisa et al, 1977] and phydroxyacetanilide [1.341 (6) Å ; Haisa et al, 1974], and other amide derivatives, such as acetanilide (1.330 Å ; Brown & Corbridge, 1954) or trans-N-phenylformamide [1.3359 (18) Å ;…”