LIGAND DISPLACEMENT-REACTIONS FROM THE COORDINATION SPHERE OF [CIS-CO(NH3)(4)(NO2)(2)]NO3 - THE CRYSTAL AND MOLECULAR-STRUCTURES OF [CIS-CO(NH3)(4)(OH)CL]CL (I) AND [CO(NH3)(4)(OXALATO)](2)[TRANS-(NH3)(OH)CO(OXALATO)(2)]CENTER-DOT-4H(2)O (II)

Compound (I) crystallizes in the space group Pnma with cell constants a = 13.295(2), b = 10.320(1), c = 6.732(1); V= 923.63 Angstrom(3), d(calc; M = 214.97, z = 4) = 1.546 gm cm(-3). Data (2340 total reflections) were collected over the range 4 degrees less than or equal to 20 less than or equal to 70 degrees and corrected for absorption (mu = 23.804 cm(-1)). The cation is a cis-chlorohydroxo species in which all the hydrogen atoms were accurately located and refined. Refinement of the heavy atoms with anisotropic thermal parameters and of the hydrogen atom positions (B = 4.0 Angstrom 2, fixed) led to the final R(F) and R(W)(F) factors of 0.033 and 0.039, respectively. Compound (II) crystallizes in the monoclinic space group PZ,ln with cell constants a = 11.429(2), b = 8.298(2), c = 14.512(2)Angstrom, beta = 102.25 degrees; V = 1344.895 Angstrom(3); d(meas., picnometer) = 1.845 gm cm(-3) d(calc; M = 771.22, Z = 2) = 1.815 gm cm(-3). A total of 3488 unique data were collected over the range 4 degrees less than or equal to 20 less than or equal to 60 degrees, of which 1976 wee used in the final refinement cycle. The data were corrected for absorption (mu = 19.111 Cm-1) The anion of this compound lies on an inversion centre; therefore NH, and the OH are disordered. All other hydrogen atoms present in the cation and anion, as well as of the waters of hydration, were located in the X-ray study. Refinement of the heavy atoms with anisotropic thermal parameters while adding the hydrogen atoms as fixed contributions (B = 4.0 Angstrom(2)) produced final values of the discrepancy indices of R(F) = 0.044 and R(W)(F) = 0.036. Both compounds were obtained during efforts tb prepare single crystals of [Co(NH3)(4)(oxalato)]Cl starting from [Co(NH3)(4)(NO2)(2)](NO3), oxalic acid and NaCl, and their identification is of interest from the standpoint of ligand replacement reactions. The presence or absence of the trans effect was investigated and we conclude that this effect can be observed or masked depending on the nature of the charge-compensating ions present in the crystals.