C19H160 , Mr = 260.3, trigonal, R3, a = 19.307 (3), c = 26.735 (4) A, V= 8631 (2) A 3, Z= 24, Dx = 1.20 g cm -3, a(Mo Ka) = 0.71073/~, /.~ = 0.7 cm -1, F(000) = 3312, T = 294 K, R = 0.083, wR = 0.068 for 1022 observed reflections. The structure contains hydrogen-bonded pyramidal tetramers (which have approximate 32 symmetry) with one molecule lying on a crystallographic threefold axis and another in a general position. The analysis was complicated by disorder in the crystal lattice where 71% of the tetramers occupy one orientation and 29% another; these moieties have their phenyl rings in the same volume elements in the lattice. The O...O separations in the hydrogen-bond systems are 2.884 (10) and 2.896 (11)/~ in the major tetramer and 2.80 (3) and 2.90 (3) A in the minor tetramer.