Solid-state coordination chemistry of oxalate (ox) compounds continues to receive much attention, with new structure types being reported for even the simplest binary oxalates. [1] In anhydrous materials complex network structures are formed owing to the high degree of ox 2ร coordination (bridging up to six metal ions). In contrast hydrates and materials containing additional noncoordinating cations [2] tend have reduced oxalate coordination, linking only two metals with the symmetric bischelating mode as the dominant bridging motif in the network structure. While there are a great many hydrated ternary oxalates very few anhydrous salts are known. Most ternary oxalates are formed at high ox 2ร :M n+ ratios (M = metal center) resulting in simple discrete anionic complexes with [M(ox) 2-4 ] mร compositions although in a few cases the [M q (ox) r ] mร component forms an extended network structure. The oxalate dianion is well known to mediate a significant antiferromagnetic exchange interaction when it bridges paramagnetic ions, and transition-metal oxalates [5] have played a key role in the development of molecular-based magnetism. New oxalate-bridged transition-metal networks are likely to provide many new and useful model magnetic systems.
We have used hydrothermal synthesis to produce a new anhydrous ternary metal oxalate; K 2 M(ox) 2 which comprises [*] Prof.