X-RAY D m a I O N ANALYSIS.’-A total of 4358 reflections were collected up to 8 max of 26” on a
CAD4 diffractometer at 27’ using Mo& (A=0.71073 A). The data were collected by the co-28 method,
1813 observed reflections with 1>3o(Z), and were corrected for Lorentz-polarization effect but not for
absorption. The structure was solved by using the direct method DIRDIF (18). All non-hydrogen atoms
were refined anisotropically by full-matrix least squares refinement on a microvax I1 minicomputer to
R=0.052, wR=0.057 for the observed reflections, w=[02(F)+0.0004~+1 1-l. Hydrogen atoms were
generated geometrically at C-H 0.95 A and were allowed to ride on their respective parent atoms with B
fixed at 1.3 times that of the parent atom. Atomic coordinates for the non-hydrogen atoms and their
equivalent isotropic displacement parameters are given in Table 3