Mr. Sundberg et al., DISSIMILARITIES IN THOXYBENZOATO-O)-BIS(1,3-DIAMINOPROPANE-N,N')M(II)(M = CU, NI) COMPLEXES, Inorganica Chimica Acta, 266(1), 1997, pp. 47-53
The structures of trans-di thoxybenzoato-O)bis(1,3-diaminopropane-N,N'
)Cu(II) (1) and the corresponding nickel(II) analogue (2) were determi
ned by single-crystal X-ray diffraction methods. The compounds crystal
lise in the monoclinic system, space group P2(1)/a (No. 14). 1: C22H32
CuN4O6, M-r = 514.25, a = 10.318(2), b = 9.620(2), c = 12.7296(14) Ang
strom, beta = 103.910(14)degrees, V = 1226.5(4) Angstrom(3), Z = 2; 2:
C22H32NiN4O6, M-r = 509.22, a = 10.100(2), b = 9.7220(11), c = 12.741
(5) Angstrom, beta = 99.86(3)degrees, V = 1232.5(5) Angstrom(3), Z=2.
The compounds display crystal chemical isotypism. They are composed of
discrete complex units connected by hydrogen bonds mediated by amino
and carboxylate groups. Each complex unit consists of a central metal
ion located at a centre of symmetry, six-membered chelate rings formed
by 1,3-diaminopropane and axially coordinated para-methoxybenzoate an
ions. The most notable difference between the nickel(II) and copper(II
) complex units is found in the axial M-O bond lengths, which are 2.14
4(2) and 2.497(4) Angstrom, respectively. The EHMO calculations assist
ed by ESR and magnetic susceptibility measurements give the values of
7 and 1% for the d-s mixing to explain the axial elongation in 1 and 2
, respectively. Another difference is seen in the different skewness o
f the chelate rings. Although the hydrogen bonding network is similar
in both compounds, there are clear differences in the N-H stretchings
in the IR spectra. Differences in the relative thermal motions of the
non coordinated oxygen atoms of the carboxylate groups are probably de
pendent primarily on the central metal atom and secondarily on hydroge
n bonding. (C) 1997 Elsevier Science S.A.