Zinc Hydrazide and Zinc Alkoxide Hydrazide Cages with Zn 4 N 8 and Zn 4 N 6 O Cores – Cluster Isomerism as a Result of Subtle Changes in Ligand Size

The hydrazide cluster [( i PrZn) 4 (NHNMe 2 ) 4 ] ( 1 ) was synthesised by the reaction of diisopropylzinc with N , N ‐dimethylhydrazine and was characterised by 1 H‐ and 13 C NMR and IR spectroscopy, mass spectrometry, elemental analysis and X‐ray crystallography. This compound forms asymmetric aggregates containing Zn 4 N 8 cores. The Zn atoms in these aggregates are arranged in topological tetrahedra in which the triangular faces are bridged by NHNMe 2 substituents. Each NH group is connected to two Zn atoms and each NMe 2 group to one Zn atom. Alkoxide clusters were prepared in one‐pot syntheses by treating diisopropylzinc solutions with mixtures of N , N ‐dimethylhydrazine and ROH (R = Et, i Pr). The resulting compounds have the formula [( i PrZn) 4 (NHNMe 2 ) 3 (OR)] [R = Et ( 3 ), i Pr( 4 )] and contain Zn 4 N 6 O cages, such that one NHNMe 2 in 1 is replaced by one alkoxide group. Two different aggregation modes were found for these Zn 4 N 6 O cages. In compound 3 , one Zn atom is bound to two NMe 2 groups and one NH group. The other three Zn atoms each have three bonds to NH groups and one dative bond to an NMe 2 group. The cage consists of one four‐membered and one six‐membered ring as well as four five‐membered rings. In compound 4 , the fourth zinc atom is exclusively bonded to three anionic NH functions in such a way that the rings in the cage are all five‐membered. Compounds 3 and 4 were characterised by NMR spectroscopy and single‐crystal X‐ray diffraction. Hydrazide hydroxide clusters were also obtained through the reaction of a diisopropylzinc solution with N , N ‐dimethylhydrazine and a small amount of water. The structure of the resulting cocrystalline material, [( i PrZn) 4 (NHNMe 2 ) 4 ] · [( i PrZn) 4 (NHNMe 2 ) 3 (OH)] ( 2 ), was also confirmed by X‐ray diffraction. The hydroxide cluster in 2 contains a Zn 4 N 6 O cage, with a similar aggregation mode to that of 4 . (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)