The crystal and molecular structure of bis[(1,2-dihapto-3,5-dimethylpyrazolido)-nallylpalladium(II)], C16H24N4Pd v has been determined by X-ray diffraction techniques. The crystals are monoclinic, P2Jc (No. 14), with a=8.752(1), b= 18.932(2), c= 11.780(3) •, and fl= 109.78(1) ~ The observed crystal density (1.746 gcm -3) agrees well with that calculated on the basis of four molecules per unit cell (1.754 g cm-3). The structure has been refined by full-matrix least-squares techniques to a final R 1 value of 0.045 (R2----0.056) for 2974 unique reflections with ./net)7 counts sec -1. The Pd2N 4 ring is in a boat conformation in which the two palladium atoms are 1.113 and 1.064 A out of the plane defined by the four nitrogen atoms. The Pd-C bond distances to the terminal atoms of the 7r-allyl groups (2.12 A) are longer than those to the central carbon atoms (2.06 A). The molecule possesses approximate mm2(C2, ) symmetry.

The structure of exo-7-chloro-7-phenyl-2,5-dioxabicyclo[4,1,O]heptane has been determined by singlecrystal X-ray diffraction methods. The crystals are monoclinic, P21/n with a= 5"840 (1), b= 16.039 (1), c= 10"692 (1)A, fl=90"919 (6) ° and Z=4. Intensity data were collected on a manually operated diffractometer using Cu K~ radiation. The structure was solved by direct methods and has been refined by block-diagonal least-squares techniques to R = 0"068 (weighted R = 0"056) including all the hydrogen atoms. The geometry of the cyclopropyl ring is normal. The dioxanyl ring has adopted an envelope conformation in which three of the C-O distances are significantly shortened. This unusual geometry of the six-membered ring is the consequence of the strain introduced by fusion of the three-membered and six-membered rings.

Abstract. C12H13OC1, F.W. 208-7; monoclinic, P21/c; a= 11.929 (1), b=7.469 (1), c= 11.900 (2) A, fl=96.25 (1) °; Dx= 1.315 g cm-3 for Z=4, Do= 1.317 g cm-3; V= 1054 A3;/t=28.9 cm -1. The structure was solved by the heavy-atom method and refined to R=0.074.The tetrahydropyran ring is in an envelope conformation with only one atom being significantly out of the plane defined by the other five non-hydrogen atoms of that moiety. The phenyl ring is oriented parallel to the bridgehead bond of the bicyclic system. endo-7-CHLORO-7-PHENYL-2-OXABICYCLO[4,1,0]HEPTANE