Crystal Engineering 4 (2001) 309–317 www.elsevier.com/locate/cryseng Interpenetration of covalent and noncovalent networks in the crystal structures of {[M(4,4'- bipyridine) 2 (NO 3 ) 2 ]•2p-nitroaniline} n where M=Co, 1, Ni, 2, Zn, 3 B. Moulton, E.B. Rather, M.J. Zaworotko * Department of Chemistry, University of South Florida, 4202 East Fowler Avenue, Tampa, FL 33620- 5250, USA Received 29 March 2001; accepted 4 April 2001 Abstract The synthesis and crystal structures of {[M(4,4'-bipyridine) 2 (NO 3 ) 2 ]•2p-nitroaniline} n , M=Co, 1, Ni, 2, Zn, 3, are described. 1, 2 and 3 crystallize in the form of compounds that can be described as interpenetrating covalent and noncovalent networks. Analysis of the crystal packing in these compounds reveals that the p-nitroaniline molecules form a noncovalent net- work that is complementary from a topological perspective with [M(4,4'-bipyridine) 2 (NO 3 ) 2 ] networks, which exist as square grids. These structures are interpreted in the broader perspec- tive of crystal engineering strategies and development of new hybrid materials.  2001 Elsevier Science Ltd. All rights reserved. Keywords: Interpenetration; Nitroaniline; Coordination polymers; Crystal structure; Noncovalent 1. Introduction The rational design of new classes of functional solid based upon the development of strategies for controlling intermolecular interactions and coordination bonds rep- resents a promising aspect of crystal engineering [1–4]. Such compounds, which can be regarded as open framework coordination polymers, offer opportunities to impact * Corresponding author. Fax: +1-813-974-1733. E-mail address: zaworo@chuma1.cas.usf.edu (M.J. Zaworotko). 1463-0184/01/$ - see front matter  2001 Elsevier Science Ltd. All rights reserved. PII:S1463-0184(01)00023-5