Using N,N'-diarylformamidinate (DArF) ligands containing different substituents of varying steric properties as the supporting ligands, four Zn complexes of atypical structural geometries were successfully synthesized and fully characterized. Detailed structural comparison indicated steric hindrance of the ligands was a crucial factor in governing the geometry and nuclearity of the Zn products. DArFs with low steric hindrance to the metal centers produced two trinuclear Zn clusters (1 and 2) where all ligands were in non-symmetric coordination modes in both solid state and solution phase. DArFs with relatively bulky substituents led to the formation of bimetallic complexes 3 and 4 in a pseudo-paddlewheel geometry where each two Zn cores were held together by two DArFs parallel to each other. This study, together with the monozinc complex {HC(NDipp) 2 } 2 Zn (Dipp = 2,6-diisopropylphenyl) in the literature, indicated that an increase in steric demands of the ligands lead to a decrease in nuclearity of the Zn-formamidinate complexes. All product complexes were relatively thermally

Synthesis and characterization of a new tripodal polydentate pyridylamine C L and an improved synthesis of analogue N L were developed.Acidified salts of the two polyamines ( C LH and N LH), one trizinc (1), and two monometallic complexes (2 and 3) were synthesized and structurally characterized.Protonation of the polyamines occurred at the pyridine N atoms, strongly supported by the hydrogen bonds between the cations and anions in the extended network. Structural analysis of the three complexes supported by N L demonstrated its versatile coordination modes. Graphic abstract:Convenient synthesis of two tripodal polydentate pyridylamines was accomplished.Structural analysis of their acidified salts determined that protonation of the polyamines occurred at the pyridine N atoms. Versatile coordination modes of one pyridylamine with late first-row transition metal atoms were also revealed.

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