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The cobalt(II) complexes of formula [Co(NCS)
2L
2] and [Co(NCS)
2L′
4] (L = imidazole (iz) derivatives, I-Meiz (
1), Z-Meiz (
2), 2-Etiz (
3), 2-Isopropiz (
4), 2-Pheniz (
5), 1,2-Me
2iz (
6), Biz (
7), 2-Mebiz (
8), 2-Etbiz (
9); L′ = iz (
10), 1-Meiz (
11)) have been synthesized and characterized by spectroscopic methods and magnetic measurements. The crystal and molecular structures of complexes
6 and
11 have been determined by X-ray diffraction methods. Complex
6 crystallizes inthe orthorhombic space group
Pnma with cell constants
a=9.209 (3),
b = 12.462 (5), c = 14.851(3)
A
̊
; V = 1704.3(9)
A
̊
3, D (
calc., Z = 4) = 1.43
g cm
−3, M
r
=367.35, F(000)=640
,
λ(
Mo Kα)=0.71079
A
̊
,
μ=11.2 cm
−1 and
T=293 K. Complex 11 crystalizes in the monoclinic space group
P2
1/
nwith cell constants
a=7.689(2),
b=11.095(1),
c=14.156(2)
A
̊
, β=93.46(2)°; V=1205.4(3)
A
̊
3, D (
calc., Z=2)=1.39
g cm
−3, M
r
=503.51, F(000)=534, λ(
Mo Kα)=0.71079
A
̊
,
μ=8.56 cm
−1 and
T=293 K. 2553 (
6) and 2485 (
12)reflections were collected over the range 1≤
θ≤25; from these, 1571 (
6) and 1977 (
11) (independent with
I≥3
σ(
I)) were used in the structural analysis. The final value of the
R
w residual was 0.077 and 0.042 for (
6) and
11, respectively. The structure of
6 is built up by [Co(NCS)
2(1,2-Me
2iz)
2] mononuclear units where the metal atom exhibits an approximately tetrahedral configuration: the CoN bond distances and NCoN bond angles vary in the range 1.958(8)−1.922(8) Å and 114.7(3)−108.3(3)°, respectively. The structure of
11 consists of [Co(NCS)
2(1-Meiz)
4] monomeric units where two N-coordinated thiocyanate groups in
trans position and four 1-methylimidazole ligands build a slightly distorted CoN
6 octahedral environment. The CoN bond lengths lie i the range 2.158(2)–2.135(3) Å being significantly longer than the related ones observed in
6.