Synthesis, Structure, and Reactivity of a Tetranuclear Cerium(IV) Oxo Cluster Supported by the Kläui Tripodal Ligand [Co(η⁵‐C₅H₅){P(O)(OEt)₂}₃]⁻

Abstract

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.

Protactinium and the intersection of actinide and transition metal chemistry

“…The formation of discrete tetranuclear metal clusters about a tetrahedral oxygen atom are rare for the actinides with few examples known to date 31 . However, a variety of tetranuclear Ce(IV) complexes with a tetrahedral motif are known 32 , 33 .…”

Ceric Ammonium Nitrate and Ceric Ammonium Chloride as Precursors for Ceric Siloxides: Ammonia and Ammonium Inclusion

“…While various studies during the past years have substantiated that weakly nucleophilic alkoxy ligands provide a highly stabilizing coordination environment for ceric complexes,, reports on siloxy derivatives have remained scarce. The available data comprise potassium ate complexes of disiloxanediolates and the Kläui ligand‐stabilized [Ce(L OEt ){OSiPh 3 } 3 ], accessed via treatment of the oligomeric oxo‐hydroxo complex [Ce 4 (L OEt ) 4 (O) 5 (OH) 2 ] with HOSiPh 3 . A ceric metallasilsequisiloxane derivative was generated via a tandem protonolysis oxidation reaction of [Ce{N(SiMe 3 ) 2 } 3 ] in the presence of pyridine, nicely pointing out the stabilizing influence of the dianionic silsequisiloxane ligand on the tetravalent cerium ion .…”

Redox Active Hexanuclear Mixed Valence Dicationic Ce(III)/Ce(IV) Coordination Clusters

“…[ 18 ] There are literature precedents for polymeric Ce III 3 ‐caboxylate network, [ 21 ] clusters containing Ce(IV) 4 (µ 4 ‐O), [ 22 ] Ce IV 4 (µ 4 ‐O)(µ‐O) 2 , [ 23 ] and their perxo‐analogue. [ 24 ] Ce IV 3 (µ‐O) 3 and Ce IV 6 (µ 3 ‐O) 4 (µ 3 ‐OH) 4 cores have been stabilized by heteropolyoxometalates. [ 25 ] Ce IV 6 (µ 3 ‐O) 8 , Ce IV 6 (µ 3 ‐O) 4 (µ 3 ‐O) 4 [ 6 ] and Ce IV 6 (µ 6 ‐O)(µ‐OH) x [ 26–27 ] units have been stabilized by carboxylate ligands.…”

“…The Ce(III) ion is a redox active cation with E 1/2 = 1.61 V and can form Ce(IV) ion under certain reaction conditions. [6][7][8][14][15][19][20][21][22][23][24][25][26][27] Ce(III) ion is prone to undergo oxidation when a reaction is carried out under aerobic condition in the presence of a nitrogen donating [22][23][24][25][26][27] base/ligand possibly via formation of Ce(III)(NO 3 ) 3 (N-donating ligands) species as an intermediate. Recently, Ce(IV)-oxo complexes were obtained via inner sphere nitrate (NO 3 -) reduction.…”

“…[11] When we carried out the similar reaction under argon atmosphere, the color of the solution remained yellow even after one day suggesting that the aerial oxygen molecules are required to oxidise Ce(III) to Ce(IV). [22][23][24][25][26][27] The latter ion is responsible for the brown color of the reaction mixture. In our case, the mixed oxygen (O 3 ) and nitrogen (N) donor dianionic (L-R) 2 Table S10) which is in equilibrium with three Ce ( Table S11).…”