Novel topologies in NiIIcluster chemistry: Incorporation of alkaline-earth metals in the new NiII6MgII2 and NiII8MII M Sr, Ba cagesElectronic supplementary information (ESI) available: Fig. S1. PLATON representation of [Ni8Sr(OH)2(ppo)6(piv)10(Hppo)5(Hpiv)2(MeCN)] (3). See http://www.rsc.org/suppdata/dt/b3/b304713j/

The reaction of the complex Ni2H2Opiv4Hpiv41 Hpiv pivalic acid with Hppo 3-phenylpyrazolin-5-one in the presence of a base of an alkaline-earth metal MII MgII, SrIIor BaII has led to three different NiIIclusters whose structures are controlled by the nature of MII. The formulae of the new heteronuclear cages are Ni6Mg2OH2ppo4piv10Hppo4MeOH22, Ni8SrOH2ppo6piv10Hppo5Hpiv2MeCN 3 and Ni8BaOH2ppo6piv10Hppo5.3Hpiv0.7MeCN24. Magnetic measurements indicate that the spin ground state of 2consists of two independent S 3 units, while the presence of two non-interacting S 2 fragments in the molecule is postulated for compounds 3and 4.