The Influence of Functional Group Orientation on the Structure of Zinc 1,1,4‐Trimethylthiosemicarbazide Dicarboxylates: Probing the Limits of Crystal Engineering Strategies

The reaction of [Zn(tmtsc) 2 ](NO 3 ) 2 [tmtsc = 1,1,4‐trimethylthiosemicarbazide, MeNHC(S)NHNMe 2 ] with a range of sodium dicarboxylates has been shown to lie on the borderline between commonly used crystal engineering strategies. The products exhibit a wide range of structural diversity with the main driving force being the relative orientation of the carboxylate groups. Thus, fumarate leads to the hydrogen‐bonded aggregate [Zn(tmtsc) 2 (OH 2 )][fumarate] ( 2 ) in which cations and anions are linked by hydrogen bond donor‐donor acceptor‐acceptor (DD:AA) interactions, whereas isophthalate and (+)‐camphorate lead to coordination polymers [Zn(tmtsc)(μ‐isophthalate)] ( 3a ) and [Zn(tmtsc)(μ‐camphorate)] ( 4 ) with the metal centres linked by bridging dicarboxylate ligands. In the case of isophthalate, a hydrated product [Zn(tmtsc)(μ‐isophthalate)]·H 2 O ( 3b ) was also characterised, although microanalysis and powder X‐ray diffraction revealed this to be a minor product. Incorporation of water was shown to lead to a change in carboxylate coordination mode from η 1 in 3a to η 2 in 3b . Use of terephthalate leads to the compound [{Zn(tmtsc)(OH 2 )} 2 (μ‐terephthalate)][terephthalate]·2H 2 O ( 5 ), in which half of the terephthalates bridge metal centres, to form dimers, and the remainder link the dimeric cations through DD:AA hydrogen bond interactions. Homophthalate leads to discrete dimers [Zn(tmtsc)(μ‐homophthalate)] 2 ( 6 ), whereas acetylenedicarboxylate yields the unexpected compound [Zn(tmtsc) 2 (OH 2 )][O 2 CCH=CC(O)N(Me)C(=NNMe 2 )S] 2 ·H 2 O ( 7 ) in which the dicarboxylate has reacted with tmtsc to give a 2‐hydrazono‐4‐oxo‐1,3‐thiazolidineacetate, which is subsequently trapped in the solid state by DD:AA hydrogen bonding interactions with [Zn(tmtsc) 2 (OH 2 )] 2+ . All products were characterised by single crystal X‐ray crystallography, and the representational nature of these crystal structures to the bulk materials was confirmed by microanalysis and powder diffraction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)