title: A second monoclinic modification of triphenyl-phosphine oxide hemihydrate.
abstract: In the crystal of the title compound, C(18)H(15)OP·0.5H(2)O, a water molecule links to two adjacent triphenylphosphine molecules by way of O-H⋯O hydrogen bonds. The crystal is twinned, the minor twin component being 36%.
authors.affiliation: Department of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Seik Weng
authors.initials: SW
authors.lastname: Ng