Downloaded By: [Monash University] At: 16:24 24 March 2007 Mol. Crw. and Lq. Cry, 1999. Vol 335, pp. 313-322 Reprint, available directly from the publisher Photocopying permitted hy licen5e only 0 1999 OPA (Oversea\ Puhli*her* Aswciation) N.V Puhlkhed hy liceme under the Gordon and Brcdch Science Puhlihhzrr imprinl Printed in Malaysia Molecular Magnetism in Manganese Dicyanamide Extended Network Structures KEITH S. MURRAYa, STUART R. BATTENa, BOUJEMAA MOUBARAKIa, DAVID J. PRICEa and RICHARD ROB SON^ "Depurtment of Chemistry, Monush University, Clayton, Victoria 3168, Australia and bSchool of Chemistry, University of Melbourne, Parkville, Victoria 3052, Australia Dicyanamide, dca- (N(CN)z-), forms an extended rutile-like single net in the binary com- plex, Mn"(dca)2, in which dca groups bridge the Mn" ions via the nitrile and amide nitrogen atoms. A trihydrate, which forms in the synthesis, displays an unusual structure consisting of square channels, formed by sheets of Mn(d~a)2(H~O)~, into which are inserted linear chains of Mn(dca)2(H20)2. Clathrated water molecules form H-bonded networks with the coordi- nated water and dca species. This trihydrate displays weak antiferromagnetic coupling between the high-spin Mn(I1) ions without long-range ordering. Mn(dca)2alsodisplays weak antiferromagnetic coupling, but with an unusual magnetic phase transition being noted at T, = 16K, particularly in low applied-fields. Dehydration of Mn(d~a)~*3H~O yields Mn(dca)2with the same magnetic transition at 16K. Keywords: molecular magnetism; dicyanamide; manganese: crystal structure; coordination polymer [ 1025113 I3