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.

Tetravalent cerium alkoxide complexes supported by the Klaüi tripodal ligand [Co(η 5 -C 5 H 5 ){P(O)(OEt) 2 } 3 ] − (L OEt − ) have been synthesized, and their nucleophilic and redox reactivity have been studied. Treatment of the Ce(IV) oxo complex [Ce IV (L OEt ) 2 (O)(H 2 O)]•MeCONH 2 (1) with i PrOH or reaction of [Ce IV (L OEt ) 2 Cl 2 ] (2) with Ag 2 O in i PrOH afforded the Ce(IV) dialkoxide complex [Ce IV (L OEt ) 2 (O i Pr) 2 ] (3-iPr). The methoxide and ethoxide analogues [Ce IV (L OEt ) 2 (OR) 2 ] (R = Me (3-Me), Et (3-Et)) have been prepared similarly from 2 and Ag 2 O in ROH. Reaction of 3-iPr with an equimolar amount of 2 yielded a new Ce(IV) complex that was formulated as the chloro-alkoxide complex [Ce IV (L OEt ) 2 (O i Pr)Cl] (4). Treatment of 3-iPr with HX and methyl triflate (MeOTf) afforded [Ce(L OEt ) 2 X 2 ] (X − = Cl − , NO 3 − , PhO − ) and [Ce IV (L OEt ) 2 (OTf) 2 ], respectively, whereas treatment with excess CO 2 in hexane led to isolation of the Ce(IV) carbonate [Ce IV (L OEt ) 2 (CO 3 )]. 3-iPr reacted with water in hexane to give a Ce(III) complex and a Ce(IV) species, presumably the reported tetranuclear oxo cluster [Ce IV 4 (L OEt ) 4 (O) 5 (OH) 2 ]. The Ce(IV) alkoxide complexes are capable of oxidizing substituted phenols, possibly via a protoncoupled electron transfer pathway. Treatment of 3-iPr with ArOH afforded the Ce(III) aryloxide complexes [Ce III (L OEt ) 2 (OAr)] (Ar = 2,4,6-tri-tert-butylphenyl (5), 2,6-diphenylphenyl ( 6)). On the other hand, a Ce(III) complex containing a monodeprotonated 2,2′-biphenol ligand, [Ce III (L OEt ) 2 ( t Bu 4 C 12 H 4 O 2 H)] (7) ( t Bu 4 C 12 H 4 O 2 H 2 = 4,4′,6,6′-tetra-tert-butyl-2,2′-biphenol), was isolated from the reaction of 3-iPr with 2,4-di-tert-butylphenol. The crystal structures of complexes 3-iPr, 3-Me, 3-Et, and 5−7 have been determined.