title: Single-crystal X-ray diffraction and NMR crystallography of a 1:1 cocrystal of dithianon and pyrimethanil.
abstract: A single-crystal X-ray diffraction structure of a 1:1 cocrystal of two fungicides, namely dithianon (DI) and pyrimethanil (PM), is reported [systematic name: 5,10-dioxo-5H,10H-naphtho[2,3-b][1,4]dithiine-2,3-dicarbonitrile-4,6-dimethyl-N-phenylpyrimidin-2-amine (1/1), C14H4N2O2S2·C12H13N2]. Following an NMR crystallography approach, experimental solid-state magic angle spinning (MAS) NMR spectra are presented together with GIPAW (gauge-including projector augmented wave) calculations of NMR chemical shieldings. Specifically, experimental1H and13C chemical shifts are determined from two-dimensional1H-13C MAS NMR correlation spectra recorded with short and longer contact times so as to probe one-bond C-H connectivities and longer-range C...H proximities, whereas H...H proximities are identified in a1H double-quantum (DQ) MAS NMR spectrum. The performing of separate GIPAW calculations for the full periodic crystal structure and for isolated molecules allows the determination of the change in chemical shift upon going from an isolated molecule to the full crystal structure. For the1H NMR chemical shifts, changes of 3.6 and 2.0 ppm correspond to intermolecular N-H...O and C-H...O hydrogen bonding, while changes of -2.7 and -1.5 ppm are due to ring current effects associated with C-H...π interactions. Even though there is a close intermolecular S...O distance of 3.10 Å, it is of note that the molecule-to-crystal chemical shifts for the involved sulfur or oxygen nuclei are small.
authors.affiliation: Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom.
authors.forename: Ann Christin
authors.initials: AC
authors.lastname: Pöppler
authors.affiliation: Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom.
authors.forename: Emily K
authors.initials: EK
authors.lastname: Corlett
authors.affiliation: Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom.
authors.forename: Harriet
authors.initials: H
authors.lastname: Pearce
authors.affiliation: International Research Centre, Syngenta, Jealott's Hill, Bracknell, Berkshire RG42 6EY, United Kingdom.
authors.forename: Mark P
authors.initials: MP
authors.lastname: Seymour
authors.affiliation: International Research Centre, Syngenta, Jealott's Hill, Bracknell, Berkshire RG42 6EY, United Kingdom.
authors.forename: Matthew
authors.initials: M
authors.lastname: Reid
authors.affiliation: International Research Centre, Syngenta, Jealott's Hill, Bracknell, Berkshire RG42 6EY, United Kingdom.
authors.forename: Mark G
authors.initials: MG
authors.lastname: Montgomery
authors.affiliation: Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom.
authors.forename: Steven P
authors.initials: SP
authors.lastname: Brown
keywords: C—H...π interactions; NMR crystallography; cocrystal; dithianon; fungicides; hydrogen bonding; pyrimethanil; solid-state NMR