摘要:
Chemical Corn m u n i cat ions NUMBER 611965 24 MARCH ___ -~ The Molecular Structure of Dichloro- 1,4,8,11 -Tetra-azacyclotetradecanenickel( 11) By B. BOSNICH, R. MASON, P. J. PAULING, G. B. ROBERTSON, and M. L. TOBE [William Ramsey and Ralph Forster Laboratories, University College, London (B.B., P. J.P., and M.L.T.), and The Department of Chemistry, The University, Shefield (R.M. and G.B.R.)] A NUMBER of complexes of 1,4,8,1l-tetra-azacyclo- tetradecane1f2 with first-row transition-metal ions have been prepared recently314 and are of interest in connection with the stereochemical consequences of substitution in octahedral complexes. Com- plexes of nickel(I1) halides with this secondary amine show interesting variations in magnetic properties4 and, together with the question of the conformation of the co-ordinated ligand, led to an X-ray analysis of the crystal structure of dichloro- 1,4,8,1l-tetra-azacycIotetradecanenickel(II) .The crystals are monoclinic with a = 13.644, b = 8.355 A, c = 6.541 A, /3 = 104.58"; the space group is P2,/a, the two molecules per unit cell of C,,N4H,,Cl,Ni being required to be strictly centrosymmetric. The molecular structure is shown in the Figure and is the result of a least squares analysis of the three-dimensional data which has converged to a present discrepancy index of 0.047. Average standard deviations are 0.003 (Ni-Cl), 0.008 (Ni-N), 0.015 (C-C and G N ) , and 0.06 (G-H and N-H). The symmetry of the ligand field around the nickel ion is less than D4&. Deviations from 90" of such bond angles as C1-Ni-N are due to intra- molecular non-bonded interactions between chlor- ine and hydrogen atoms, the positions of the latter J.van Alphen, Rec. Trav. chim., 1937, 36, 343. a H. Stetter and K. H. Mayer, Chem. Bey., 1961, 94, 1410. B. Bosnich, C. K. Poon, and M. L. Tobe, in the press. B. Bosnich, M. L. Tobe, and G. A. Webb, in the press. being directly determined by difference density syntheses; in particular, the chlorine atoms move away from hydrogens attached to carbon and towards those bonded to nitrogen. Moreover, the C1 I I 2.492 c 5 I C4' 1,5121 1 \ c4 +c; CI 1.565 bond lengths around the nickel ion show a tetra- gonal distortion of approximately 0-15 A which may be greater in the case of the diamagnetic di-iodo-complex, as a result of increased steric98 CHEMICAL COMMUNICATIONS interactions, so that there is a change-over from the 3A 2g ground state of the dichloro-derivative (peff 3.1 B.M. at 300" K) to a lA,, state. Analyses of the crystal structures of the dibromo- and di- iodo-complexes are in progress so as to confirm or disprove this view. The results represent the first observation of the conformation of a six-membered chelate ring. The 1,3-diaminopropane rings have a chair con- formation while the ethylenediamine residues are gauche, their carbon atoms being equatorial sub- stituents on the nitrogens of the 1,3-diamino- propane rings. We thank Dr. P. B. Braun for making available an automatic diffractometer for data collection. (Received, February llth, 1965.)
ISSN:0009-241X
DOI:10.1039/C19650000097
出版商:RSC
年代:1965
数据来源: RSC