title: Very strong C-H...O, N-H...O, and O-H...O hydrogen bonds involving a cyclic phosphate.
abstract: Very short C-H...O, N-H...O, and O-H...O hydrogen bonds have been generated utilizing the cyclic phosphate [CH2(6-t-Bu-4-Me-C6H2O)2]P(O)OH (1). X-ray structures of (i) 1 (unsolvated, two polymorphs), 1...EtOH, and 1...MeOH, (ii) [imidazolium](+)[CH2(6-t-Bu-4-Me-C6H2O)2PO2](-)...MeOH [2], (iii) [HNC5H4-N=N-C5H4NH](2+)[(CH2(6-t-Bu-4-Me-C6H2O)2PO2)2](2-)...4CH3CN...H2O [3], (v) [K, 18-crown-6](+)[(CH2(6-t-Bu-4-Me-C6H2O)2P(O)OH)(CH2(6-t-Bu-4-Me-C6H2O)2PO2)](-)...2THF [4], (vi) 1...cytosine...MeOH [5], (vii) 1...adenine...1/2MeOH [6], and (viii) 1...S-(-)-proline [7] have been determined. The phosphate 1 in both its forms is a hydrogen-bonded dimer with a short O-H...O distance of 2.481(2) [triclinic form] or 2.507(3) A [monoclinic form]. Compound 2 has a helical structure with a very short C-H...O hydrogen bond involving an imidazolyl C-H and methanol in addition to N-H...O hydrogen bonds. A helical motif is also seen in 5. In 3, an extremely short N-H...O hydrogen bond [N...O 2.558(4) A] is observed. Compounds 6 and 7 also exhibit short N-H...O hydrogen bonds. In 1...EtOH, a 12-membered hydrogen-bonded ring motif, with one of the shortest known O-H...O hydrogen bonds [O...O 2.368(4) A], is present. 1...MeOH is a similar dimer with a very short O(-H)...O bond [2.429(3) A]. In 4, the deprotonated phosphate (anion) and the parent acid are held together by a hydrogen bond on one side and a coordinate/covalent bond to potassium on the other; the O-H...O bond is symmetrical and very strong [O...O 2.397(3) A].
authors.affiliation: School of Chemistry, University of Hyderabad, Hyderabad-500046, AP, India.
authors.forename: K C
authors.initials: KC
authors.lastname: Kumara Swamy
authors.forename: S
authors.initials: S
authors.lastname: Kumaraswamy
authors.forename: P
authors.initials: P
authors.lastname: Kommana
mesh_terms: D000225:Adenine / Q000737:chemistry; D018360:Crystallography, X-Ray; D003596:Cytosine / Q000737:chemistry; D006860:Hydrogen Bonding; D007093:Imidazoles / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D010755:Organophosphates / Q000737:chemistry*; D011392:Proline / Q000737:chemistry; D011726:Pyridinium Compounds / Q000737:chemistry; D014498:Uracil / Q000031:analogs & derivatives
chemical_list: D007093:Imidazoles; D010755:Organophosphates; D011726:Pyridinium Compounds; D014498:Uracil; D003596:Cytosine; D011392:Proline; D000225:Adenine