A monoclinic polymorph of N,N′-bis­(2,6-diisopropyl­phen­yl)formamidine

Jason D Masuda

doi:10.1107/S160053680802076X

. 2008 Jul 9;64(Pt 8):o1447. doi: 10.1107/S160053680802076X

A monoclinic polymorph of N,N′-bis(2,6-diisopropylphenyl)formamidine

Jason D Masuda ^a,^*

PMCID: PMC2962078 PMID: 21203162

Abstract

A new polymorph of N,N′-bis(2,6-diisopropylphenyl)formamidine, C₂₅H₃₆N₂, is reported, which is different from the previously reported orthorhombic structure. The molecule crystallizes in the E–anti configuration, with tautomeric disorder of the N-bonded H atoms and no clear distinction between imine and amine functionalities. The molecules form hydrogen-bonded dimers with intermolecular N⋯N distances shorter than those in the orthorhombic polymorph.

Related literature

For the orthorhombic polymorph, see: Stibrany & Potenza (2006 ▶). For synthetic details and related literature, see: Krahulic et al. (2005 ▶); Perrin (1991 ▶).

Experimental

Crystal data

C₂₅H₃₆N₂
M _r = 364.56
Monoclinic,
a = 24.169 (4) Å
b = 12.7881 (18) Å
c = 19.479 (3) Å
β = 126.735 (2)°
V = 4824.8 (12) Å³
Z = 8
Mo Kα radiation
μ = 0.06 mm⁻¹
T = 291 (2) K
0.45 × 0.34 × 0.30 mm

Data collection

Bruker SMART 1K CCD diffractometer
Absorption correction: none
12048 measured reflections
4242 independent reflections
2237 reflections with I > 2σ(I)
R _int = 0.036

Refinement

R[F ² > 2σ(F ²)] = 0.051
wR(F ²) = 0.161
S = 1.02
4242 reflections
252 parameters
H-atom parameters constrained
Δρ_max = 0.18 e Å⁻³
Δρ_min = −0.17 e Å⁻³

Data collection: SMART (Bruker, 2003 ▶); cell refinement: SAINT (Bruker, 2003 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶); software used to prepare material for publication: publCIF (Westrip, 2008 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S160053680802076X/bi2287sup1.cif

e-64-o1447-sup1.cif^{(20.3KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S160053680802076X/bi2287Isup2.hkl

e-64-o1447-Isup2.hkl^{(208KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1A⋯N1ⁱ	0.86	2.03	2.882 (4)	171
N2—H2A⋯N2ⁱ	0.86	2.05	2.910 (3)	175

Open in a new tab

Symmetry code: (i) Inline graphic .

Acknowledgments

The author thanks Saint Mary’s University for funding.

supplementary crystallographic information

Comment

Crystals of the title compound were grown from toluene solution and were found to crystallize in the monoclinic space group C2/c, different from the previously published polymorph which crystallizes in the orthorhombic space group C222₁ (Stibrany & Potenza, 2006). The molecule crystallizes in the E-anti configuration (Perrin, 1991), with tautomeric disorder of the N-bonded H atoms. The molecules form hydrogen-bonded dimers with N···N distances of 2.882 (4) and 2.910 (3) Å (Table 1). These distances are slightly shorter than that seen in the orthorhombic polymorph (2.947 Å). The two core amidine (NCNH) fragments are non-coplanar as a result of interaction between the sterically bulky 2,6-diisopropylphenyl fragments. The N1—C(1) (1.313 (3) Å) and N2—C1 (1.311 (3) Å) distances are similar in length, whereas in the orthorhombic polymorph there are distinct imine (1.288 Å) and amine (1.325 Å) functionalities.

Experimental

The title compound was prepared according to the literature procedure (Krahulic et al., 2005). Crystals were grown by evaporation of a toluene solution at room temperature.