Effects of Concurrent Sulfur and Phosphorus Incorporation in Nickel Cyclam‐Based Complexes

The concurrent presence of S‐, P‐, and N‐donor atoms in isocyclam frameworks and their corresponding nickel complexes to get insight into the influence of these different heteroatoms on their structural and electronic properties is investigated. Structural elucidation of the complexes reveals both octahedral and square‐planar coordination modes for Ni{PNSN} ( {PNSN} = 8‐phenyl‐1‐thia‐5,11‐diaza‐8‐phosphacyclotetradecane) and Ni{SNPN} ( {SNPN} = 8‐phenyl‐1‐thia‐4,12‐diaza‐8‐phosphacyclotetradecane). Moreover, it is found that in the presence of different donor atoms, the one positioned between rigid ethyl moieties primarily controls the properties of the complexes. Thus, the transition between square‐planar and octahedral conformers is slower for Ni{SNPN} as compared to Ni{PNSN} , which immediately adopts an octahedral geometry. A similar trend is observed when investigating the chemically generated Ni I species via UV/vis/NIR and EPR spectroscopy: while Ni{SNPN} forms an intermediate Ni I species that gradually converts to an undefined EPR‐silent species, Ni{PNSN} exists as a stable Ni I species.