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Ligands with multiple coordination sites are often used in the synthesis of the extended metallo-organic structures. Both pyrazolyl and acetato ligands can have a role of a ''bridge'' between the metallo-organic fragments. As a part of the study of the coordination capabilities of pyrazole-based ligands we are reporting the molecular and crystal structure of the bis(acetato)-bis(4-methyl-1H-pyrazole)-zinc(ii). Zn is coordinated by two methyl-pyrazole and two acetato ligands, in a distorted tetrahedral environment. Figure depicts molecular diagram. C-H atoms are removed for clarity. Green lines depicts intra and inter-molecular hydrogen bonds. Different pattern of non-bonding interactions involving chemically equivalent ligands influence the overall shape of the complex molecule. This is evident in different mutual position of the pyrazolyl and acetato ligands, which is associated with different hydrogen bonds. Angle between the mean planes of the pyrazole and COO (acetato) atoms connected through the intra-molecular hydrogen bond is 25.1º. Equivalent angle involving pair of ligands participating in inter-molecular interactions is 72.9º. Two neighboring complex molecules forms hydrogen bonded dimer. There are no significant inter-molecular contacts between dimmers. Association of molecular dimmers into crystal structure is achieved through the van der Waals forces. It is interesting to compare the title complex (1) with the structurally related bis(acetato)-bis(pyrazole)-zinc(ii) (2). Two molecules differ in the substituent at C4 (CH3 in 1, vs H in 2). Additionally in the crystal structure of 2 the free acetato molecule is present. In both compounds non-bonding interaction lead to formation of hydrogen bonded dimmer. In 2, this structure is stabilized by additional hydrogen bonds involving free acetato molecule. However, as in the crystal structure of 1, there are no formation of the extended molecular arrangements.
