The crystal structure of 8.1 2-diethyl-2.3.7.13.17.18-hexamethylcorrole has been elucidated by X-ray crystallographic analysis and the geometry of the macrocyclic ring system has been found to be not strictly planar. The distortions are probably caused by short N-N contacts brought on by the direct C(l)-C(19) link. The ' ruffling ' of the pyrrole rings is similar to that found in some substituted porphyrins, although individual ring geometries have been altered by the inner crowding. Crystallographic evidence suggests that the three inner hydrogen atoms are statistically distributed among the four nitrogen atoms. Packing is in the ' parallel disc ' mode and is specific for the molecular distortion.Laboratory, South Parks Road, Oxford DURING attempts at synthesis of the vitamin B,, corrin nucleus and assessments of the feasibility of various biosynthetic pathways for the porphyrins and corrins, Johnson and Kay2-* described the synthesis of a new macrocyclic system, corrole. This system, lacking a C (2O)meso-carbon bridge, appeared to have a corrin-type skeleton with 10 double bonds, involving porphyrin-like conjugation. The structure of Johnson's original compound (I), C,,H,,N4, 2,3,7,13,17,18-hexamethyl-8,12diethyl corrole has been elucidated by X-ray crystallographic analysis which confirms the organic synthetic conclusions. light petroleum (b.p. 40-60@) on chloroforni-corrole. The two forms were characterized as monoclinic ( P 2 J c ) with 2 = 4, a = 4-71, b = 38.15, G = 13.57 A, Q = 94-85', and orthorhombic (Pbca) with 2 = 8, a = 8.98, b = 36-96, and G = 14.57 A. Neither form contained solvent of crystal-lization. Because they were much larger, the orthorhombic crystals were used for data collection. Approximately 3000 independent reflections were measured using a computer-controlled four-circle diffractometer with nickelfiltered Cu-K, radiation. Lorentz, polarization and semiempirical absorption corrections 5 3 6 were then applied. The structure was solved with an automated centrosymmetric symbolic addition procedure on the Oxford KDF 9 computer. Refinement was performed using first isotropic and then anisotropic least-squares procedures, large-block 4
The three-dimensional crystal structures of the 1 : 1 complexes of 1.3.5-trinitrobenzene and bis-(N-t-butylsalicylideneiminato) -cobalt( 11). -nickel(ll), and -copper(ll) have been determined. They are essentially isomorphous and have a structure formed from pairs of donor [bis-(N-t-butylsalicylideneiminato) metal(i I)] and acceptor (1.3.5-trinitrobenzene) molecules. The 1.3.5-trinitrobenzene interacts with only one of the salicylideneiminato ligands of a given chelate. The co-ordination around the metal atom is a flattened M02N2 tetrahedron with angles between the M , N ( l ) , 0(1) and M, N(2). O(2) planes of 81' 34'. 78" 51'. and 61" 36'for the cobalt, nickel, and copper structures respectively. Inter-ligand steric strains increase with flattening but prevent the metal adopting square planar or octahedral co-ordinations. South Parks Road, Oxford OX1 30s RECENTLY the effects of ligand structure on the stereochemical and electronic properties of Schiff -base metal complexes (I) have been extensively studied in solution R (1) and in the solid by different physical methods.lS2 In connection with a part of this work a crystallographic investigation of the donor-acceptor interactions of these complexes (in which X = H, R = But) has been carried out. EXPERIMENTAL Bis-(N-t-butylsalicylidenei~zinato)cobalt (11)-1,3,5-trinitrobenzene
2566THE CRYSTAL STRUCTURE OF [Co(NHa)614CusCI17 this diminution in the size of anion would lead to a less stable structure as the cations would then be in contact with each other. In the present compound the empirical formula of the anion [Cux. 25C14.25] leads to a greater effective volume for the anion which will be much nearer to the volume of the [CuC15] 3-ion.The structure shows clearly how twinning can occur since over 60 % of the scattering material (based on f 2) lies on the diagonal (110) plane (x=y) conforming to the higher symmetry Fd3m. Two twin fragments related by reflexion across (110) differ only in the arrangement of the nitrogen atoms and the terminal C1(3) atoms, corresponding to rotations of the CuC13 groups and [Co(NH3)6] 3+ ions. These rotations are unlikely to have much effect on the rest of the structure so that this form of twinning is highly probable.The structure also gives insight into the possible formulae and structures of the solid solutions formed between [Co(NHa)6]CuCI5 and the title compound. A single crystal of an intermediate phase has been investigated and it is hoped to publish the structure in a future paper. The structure of a new diterpenoid, baccatin V, C3~H38OH, isolated from Taxus baccata L., has been determined by X-ray diffraction techniques. The crystals are orthorhombic, space group P21212~ with cell dimensions a=25.75_+0.01, b=9-31 _+0.01, ¢= 12.34+0.02 A and Z=4. The structure was solved by application of the symbolic addition procedure for phase determination. The molecule has been shown to contain an oxetan ring and to be 5fl, 2a,4a,7a, lOfl,-one 4a,10fl-diacetate 2a-benzoate. The final R value is 9.14% for 2459 observed reflexions, refining positional and anisotropic thermal parameters of non-hydrogen atoms and including 28 hydrogen positions, obtained from a AF synthesis, in the final structure-factor calculations.
Baccatin-V, C3,H3,01,, a new diterpenoid from Taxus baccata L. has been shown by X-ray analysis to contain an oxetan ring and to be 5@,20-epoxy-l@,2a,4a,-7a, log, 13~-hexahydroxytax-1 1-en-9-one 4a, 1 OP-diacetate 2cc-benzoate (I).
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