The reactivity of the cerium(IV) oxo complex [(L)Ce(═O)(HO)]·MeC(O)NH (1; L = [CoCp{P(O)(OEt)}], where Cp = η-CH) toward electrophiles and Brønsted acids has been investigated. The treatment of 1 with acetic anhydride afforded the diacetate complex [Ce(L)(OCMe)] (2). The reaction of 1 with B(CF) yielded [Ce(L)(MeCONH)][B(CF)(OH)] (3), in which the [B(CF)(OH)] anions are H-bonded to the O-bound acetamide ligands. The treatment of 1 with HCl and HNO afforded [Ce(L)Cl] and [Ce(L)(NO)], respectively. Protonation of 1 with triflic acid (HOTf) gave the diaqua complex [Ce(L)(HO)](OTf) (4), in which the triflate anions are H-bonded to the two aqua ligands. The treatment of 1 with phenol afforded the phenoxide complex [Ce(L)(OPh)] (5). The oxo-bridged bimetallic complex [(L)(MeCONH)Ce(O)NaL] (6) with the Ce-O and Na-O distances of 1.953(4) and 2.341(4) Å, respectively, was obtained from the reaction of 1 with [NaL]. Density functional theory calculations showed that the model complex [(L)Ce(MeCONH)(O)NaL] (6A; L = [CoCp{P(O)(OMe)}]) contains a polarized Ce═O multiple bond. The energy for dissociation of the {NaL} fragment from 6A in acetonitrile was calculated to be +33.7 kcal/mol, which is higher than that for dissociation of the H-bonded acetamide from [(L)Ce(═O)(HO)]·MeC(O)NH (1A) (calculated to be +17.4 kcal/mol). In hexanes containing trace water, complex 1 decomposed readily to a mixture of a tetranuclear cerium(IV) oxo cluster, [Ce(L)(μ-O)(μ-O)(μ-OH)] (7), and a cerium(III) complex, [Ce(L)(HO)][L] [8(L)], whereas the cerium/sodium oxo complex 6 is stable under the same conditions. The crystal structures of 3, 4·HO, 6, and 8(L) have been determined.

A tetranuclear Ce(IV) oxo cluster compound containing the Kläui tripodal ligand [Co(η(5) -C5 H5 ){P(O)(OEt)2 }3 ](-) (LOEt (-) ) has been synthesized and its reactions with H2 O2 , CO2 , NO, and Brønsted acids have been studied. The treatment of [Ce(LOEt )(NO3 )3 ] with Et4 NOH in acetonitrile afforded the tetranuclear Ce(IV) oxo cluster [Ce4 (LOEt )4 O7 H2 ] (1) containing an adamantane-like {Ce4 (μ2 -O)6 } core with a μ4 -oxo ligand at the center. The reaction of 1 with H2 O2 resulted in the formation of the peroxo cluster [Ce4 (LOEt )4 (μ4 -O)(μ2 -O2 )4 (μ2 -OH)2 ] (2). The treatment of 1 with CO2 and NO led to isolation of [Ce(LOEt )2 (CO3 )] and [Ce(LOEt )(NO3 )3 ], respectively. The protonation of 1 with HCl, ROH (R=2,4,6-trichlorophenyl), and Ph3 SiOH yielded [Ce(LOEt )Cl3 ] (3), [Ce(LOEt )(OR)3 ] (4), and [Ce(LOEt )(OSiPh3 )3 ] (5), respectively. The chloride ligands in 3 are labile and can be abstracted by silver(I) salts. The treatment of 3 with AgOTs (OTs(-) =tosylate) and Ag2 O afforded [Ce(LOEt )(OTs)3 ] (6) and 1, respectively. The electrochemistry of the Ce-LOEt complexes has been studied by using cyclic voltammetry. The crystal structures of complexes 1-5 have been determined.

Ruthenium thio- and seleno-nitrosyl complexes containing chelating sulfur and oxygen ligands have been synthesised and their de-chalcogenation reactions have been studied. The reaction of mer-[Ru(N)Cl3(AsPh3)2] with elemental sulfur and selenium in tetrahydrofuran at reflux afforded the chalcogenonitrosyl complexes mer-[Ru(NX)Cl3(AsPh3)2] [X = S (1), Se (2)]. Treatment of 1 with KN(R2PS)2 afforded trans-[Ru(NS)Cl{N(R2PS)2}2] [R = Ph (3), Pr(i) (4), Bu(t) (5)]. Alternatively, the thionitrosyl complex 5 was obtained from [Bu(n)4N][Ru(N)Cl4] and KN(Bu(t)2PS)2, presumably via sulfur atom transfer from [N(Bu(t)2PS)2](-) to the nitride. Reactions of 1 and 2 with NaLOEt (LOEt(-) = [Co(η(5)-C5H5){P(O)(LOEt)2}3](-)) gave [Ru(NX)LOEtCl2] (X = S (8), Se (9)). Treatment of [Bu(n)4N][Ru(N)Cl4] with KN(R2PS)2 produced Ru(IV)-Ru(IV)μ-nitrido complexes [Ru2(μ-N){N(R2PS)2}4Cl] [R = Ph (6), Pr(i) (7)]. Reactions of 3 and 9 with PPh3 afforded 6 and [Ru(NPPh3)LOEtCl2], respectively. The desulfurisation of 5 with [Ni(cod)2] (cod = 1,5-cyclooctadiene) gave the mixed valance Ru(III)-Ru(IV)μ-nitrido complex [Ru2(μ-N){N(Bu(t)2PS)2}4] (10) that was oxidised by [Cp2Fe](PF6) to give the Ru(IV)-Ru(IV) complex [Ru2(μ-N){N(Bu(t)2PS)2}4](PF6) ([10]PF6). The crystal structures of 1, 2, 3, 7, 9 and 10 have been determined.