M. Druyan, A. Reis, E. Gebert
Aug 1, 1976
Citations
0
Influential Citations
34
Citations
Journal
Journal of the American Chemical Society
Abstract
The molecular structure of di-tert-butylphosphinic acid, ((CH/sub 3/)/sub 3/C)/sub 2/PO(OH), as determined by single-crystal x-ray methods, is the first observed distinct dimeric R/sub 2/PO(OH) compound with two acid molecules linked through a centrosymmetric configuration. The molecule crystallizes in the monoclinic space group, P2/sub 1//c with cell parameters a = 8.973 (6) A, b = 13.130 (9) A, c = 10.539 (7) A, ..beta.. = 117.95 (3)/sup 0/, and Z = 4. The structure was solved and refined using 999 independent three-dimensional Mo K..cap alpha.. x-ray data collected with an automated diffractometer. Full-matrix least-squares refinement of 620 observations for which F/sub 0/ > 3 sigma (F/sub 0/) led to R/sub F/ = 0.059. The discrete dimer which was found contains strong, 2.506 (18) A, hydrogen bonds, in which the oxygen atoms of O--H--O are not related by a crystallographic symmetry element. The eight-membered, hydrogen bonded ring has 1 site symmetry and shows a small chair-conformation distortion from planarity. The P--O bond lengths are 1.521 (8) and 1.520 (6) A which indicates that the oxygen atoms are essentially equivalent. There appear to be weak C--H--O interactions which fix the methyl group orientations to give an overall eclipsed conformation.