A series of new heteroleptic
MN2S2 transition metal complexes with
M = Cu
2+ for EPR measurements and as diamagnetic hosts Ni
2+, Zn
2+, and Pd
2+ were synthesized and characterized. The ligands are
N2 = 4, 4′‐bis(tert‐butyl)‐2, 2′‐bipyridine (
tBu
2bpy) and
S2 =1, 2‐dithiooxalate, (dto), 1, 2‐dithiosquarate, (dtsq), maleonitrile‐1, 2‐dithiolate, or 1, 2‐dicyanoethene‐1, 2‐dithiolate, (mnt). The Cu
II complexes were studied by EPR in solution and as powders, diamagnetically diluted in the isostructural planar [Ni
II(
tBu
2bpy)(
S2)] or[Pd
II(
tBu
2bpy)(
S2)] as well as in tetrahedrally coordinated[Zn
II(
tBu
2bpy)(
S2)] host structures to put steric stress on the coordination geometry of the central Cu
N2S2 unit. The spin density contributions for different geometries calculated from experimental parameters are compared with the electronic situation in the frontier orbital, namely in the semi‐occupied molecular orbital (SOMO) of the copper complex, derived from quantum chemical calculations on different levels (EHT and DFT). One of the hosts, [Ni
II(
tBu
2bpy)(mnt)], is characterized by X‐ray structure analysis to prove the coordination geometry. The complex crystallizes in a square‐planar coordination mode in the monoclinic space group
P2
1/
a with
Z = 4 and the unit cell parameters
a = 10.4508(10) Å,
b = 18.266(2) Å,
c = 12.6566(12) Å,
β = 112.095(7)°. Oxidation and reductions potentials of one of the host complexes, [Ni(
tBu
2bpy)(mnt)], were obtained by cyclovoltammetric measurements.
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