Heteropolymetallic assemblies constructed from homometallic coordination polymers and paramagnetic metal-containing anions. Synthesis, crystal structure and magnetic properties of [Mn(4,4 0 -bipyridine-N ; N 0 -dioxide) (H 2 O) 4 ][Cr(bipy)(C 2 O 4 ) 2 ] 2 8H 2 O Sandra Bruda a , Marius Andruh a, * , Herbert W. Roesky b , Yves Journaux c , Mathias Noltemeyer b , Eric Rivi ere c a Inorganic Chemistry Laboratory, Faculty of Chemistry, University of Bucharest, Str. Dumbrava Rosie nr. 23, Bucharest 70254, Romania b Institut f ur Anorganische Chemie der Universit at, Tammannstr. 4, G ottingen D-37077, Germany c Laboratoire de Chimie Inorganique, Universit e de Paris-Sud, B^ atiment 420, F-91405, Orsay, France Received 30 November 2000; accepted 15 December 2000 Abstract The reaction of the Mn 2 (aq) and [Cr(bipy)C 2 O 4 2 (aq) ions with 4,4 0 -bipyridine-N ; N 0 -dioxide leads to a heteropoly- metallic system, [Mn(4,4 0 -bipyridine-N ; N 0 -dioxide) H 2 O 4 ][Cr(bipy)C 2 O 4 2 2 8H 2 O(1). The crystal structure of 1 consists of one-dimensional chains, 1 1 [Mn(4,4 0 -bipyridine-N ; N 0 -dioxide) H 2 O 4 2n n , with Mn(II) ions bridged by 4,4 0 -bipyridine-N ; N 0 - dioxide ligands. The in®nite homometallic chains are interconnected through hydrogen bonds with the water molecules and the [Cr(bipy)C 2 O 4 2 anions. The cryomagnetic measurements of compound 1 reveal weak anti-ferromagnetic interactions between the manganese(II) ions within the chain (J 1:2 cm 1 ). Ó 2001 Published by Elsevier Science B.V. All rights reserved. Keywords: Crystal structure; Manganese complexes; Chromium complexes; 4; 4 0 -bipyridine-N ; N 0 -dioxide complexes; Magnetic properties 1. Introduction In a series of papers [1±4], one of us has shown that bis-oxalato-chromium(III) complexes of the type [Cr(AA) C 2 O 4 2 (AA 2; 2 0 -bipyridine, 1,10-phen- anthroline) are extremely versatile building-blocks for the design of heteropolynuclear complexes. The syn- thetic approach consists of a self-assembly process be- tween [Cr(AA) C 2 O 4 2 building-blocks and ``nacked'' (actually hydrated) metal ions. It has been shown that this process is strongly in¯uenced by the coordination algorithm, as well as by the oxidation state of the as- sembling cations Ba 2 ; Mn 2 ; Cu 2 ; Co 2 ; Ni 2 ; Zn 2 ; Ag ; Na ; AsPh 4 . The crystallographic investigation of the oxalato-bridged heteropolymetallic complexes, M II fCrbipyC 2 O 4 2 g 2 H 2 O n fMCr 2 g and M I fCr bipyC 2 O 4 2 gH 2 O n {MCr}, revealed a rich variety of structures, ranging from discrete entities to 3-D frameworks. An alternative way for obtaining heteropolymetallic systems is to crystallize the fMCr 2 g and {MCr} com- pounds in the presence of ancillary ligands, which, by coordinating to the M 2 or M assembling cations, will in¯uence the topology of the metal ions in the crystal. We are especially interested in exo -bidentate (divergent) ligands, such as 4,4 0 -bipyridine, 1,2-bis(4-pyridyl)ethane, 1,2-bis(4-pyridyl)ethene, 4; 4 0 -bipyridine-N ; N 0 -dioxide. These ligands are able to generate extended structures, see for example [5±7]. In this communication, we report on the crystal structure and the magnetic properties of a new heteropolymetallic system, which is obtained by reacting the Mn 2 (aq) and [Cr(bipy)C 2 O 4 2 (aq) ions with 4; 4 0 -bipyridine-N ; N 0 -dioxide. Inorganic Chemistry Communications 4 (2001) 111±114 www.elsevier.nl/locate/inoche * Corresponding author. Tel.: +40-94-870656. E-mail address: marius.andruh@dnt.ro (M. Andruh). 1387-7003/01/$ - see front matter Ó 2001 Published by Elsevier Science B.V. All rights reserved. PII: S 1 3 8 7 - 7 0 0 3 ( 0 0 ) 0 0 2 2 3 - 9