Trapping CS₂^2– and S₃^2– between Two Ytterbium Formamidinates

Treatment of [YbII(DippForm)2(thf)n] (n = 2 (1aYb), n = 1 (1bYb); DippForm = N,N′-bis­(2,6-diisopropylphenyl)­formamidinate), with either excess CS2 or S8 gives [YbIII2(DippForm)4(CS2)] (3) and [YbIII2(DippForm)4(S2)0.5/(S3)0.5] (4) respectively. 3 is a new addition to an exclusive class of compounds containing the CS22− dianion, and 4 is the first crystallographically characterized example of a rare-earth trisulfide complex

Four-Membered Group 13 Metal(I) N-Heterocyclic Carbene Analogues: Synthesis, Characterization, and Theoretical Studies

The synthesis, spectroscopic and structural characterization of the monomeric, four-membered group 13 metal(I) heterocycles ([:M{η2-N,N‘-(Ar)NC(NCy2)N(Ar)}], M = Ga or In, Ar = C6H3Pri2-2,6) and an isomeric thallium complex are reported. Theoretical studies on these complexes, which are analogues of four-membered N-heterocyclic carbenes, suggest they should act as good σ-donor ligands

Four-Membered Group 13 Metal(I) N-Heterocyclic Carbene Analogues: Synthesis, Characterization, and Theoretical Studies

The synthesis, spectroscopic and structural characterization of the monomeric, four-membered group 13 metal(I) heterocycles ([:M{η2-N,N‘-(Ar)NC(NCy2)N(Ar)}], M = Ga or In, Ar = C6H3Pri2-2,6) and an isomeric thallium complex are reported. Theoretical studies on these complexes, which are analogues of four-membered N-heterocyclic carbenes, suggest they should act as good σ-donor ligands

Four-Membered Group 13 Metal(I) N-Heterocyclic Carbene Analogues: Synthesis, Characterization, and Theoretical Studies

The synthesis, spectroscopic and structural characterization of the monomeric, four-membered group 13 metal(I) heterocycles ([:M{η2-N,N‘-(Ar)NC(NCy2)N(Ar)}], M = Ga or In, Ar = C6H3Pri2-2,6) and an isomeric thallium complex are reported. Theoretical studies on these complexes, which are analogues of four-membered N-heterocyclic carbenes, suggest they should act as good σ-donor ligands

Selective Oxidation of a Single Metal Site of Divalent Calix[4]pyrrolide Compounds [Ln₂(N₄Et₈)(thf)₄] (Ln = Sm or Eu), Giving Mixed Valent Lanthanoid(II/III) Complexes

The samarium(II) calix[4]pyrrolide complex [Sm2(N4Et8)(thf)4] (N4Et8 = meso-octaethylcalix[4]pyrrolide) undergoes selective oxidation of one SmII site on reaction with a range of metal carbonyls giving mixed valence Sm(II/III) complexes. Thus, reactions with TM(CO)6 (TM = Mo or Cr) entrap M2(CO)102– ions between two mixed valence hosts in [{(thf)2SmII(N4Et8)SmIII(thf)(μ–OC)TM(CO)4}2]·PhMe (TM = Mo, 1; Cr, 2), while W(CO)6 on a different stoichiometry traps W(CO)52– in [{(thf)2SmII(N4Et8)SmIII}2{(μ–OC)W(CO)4}]·PhMe 3 in which the isocarbonyl group is disordered over two sites. In contrast, [Sm2(N4Et8)(thf)4] reacts with dicobalt octacarbonyl, bis(cyclopentadienyl)tetracarbonyl diiron, and dimanganese decacarbonyl to give the mixed valence species [(thf)2SmII(N4Et8)SmIII(thf)(μ–OC)TM(CO)3]·2PhMe (TM = Co, 4; Fe, 5) and [(thf)2SmII(N4Et8)SmIII(thf)(μ–OC)Mn(CO)4]·1.5PhMe 6. However, both SmII sites of [Sm2(N4Et8)(thf)4] can be oxidized as its reaction with cyclooctatetraene (COT) yields the SmIII species [(thf)SmIII(N4Et8)SmIII(COT)] 7. The analogous EuII reagent, [Eu2(N4Et8)(thf)4] induces C–halogen activation of perfluorodecalin, hexachloroethane, and bromoethane to form the mixed oxidation state species [(thf)2EuII(N4Et8)EuIII(μ–X)]2 (X = F, 8; Cl, 9; Br, 10) despite the use of a sufficient reagent to oxidize both EuII sites. The synthetic potential of the halogenido complexes was illustrated by the reaction of 10 with sodium bis(trimethylsilyl)amide to give the mixed oxidation state [(thf)2EuII(N4Et8)EuIII(N(SiMe3)2)] 11

Selective Oxidation of a Single Metal Site of Divalent Calix[4]pyrrolide Compounds [Ln₂(N₄Et₈)(thf)₄] (Ln = Sm or Eu), Giving Mixed Valent Lanthanoid(II/III) Complexes

The samarium(II) calix[4]pyrrolide complex [Sm2(N4Et8)(thf)4] (N4Et8 = meso-octaethylcalix[4]pyrrolide) undergoes selective oxidation of one SmII site on reaction with a range of metal carbonyls giving mixed valence Sm(II/III) complexes. Thus, reactions with TM(CO)6 (TM = Mo or Cr) entrap M2(CO)102– ions between two mixed valence hosts in [{(thf)2SmII(N4Et8)SmIII(thf)(μ–OC)TM(CO)4}2]·PhMe (TM = Mo, 1; Cr, 2), while W(CO)6 on a different stoichiometry traps W(CO)52– in [{(thf)2SmII(N4Et8)SmIII}2{(μ–OC)W(CO)4}]·PhMe 3 in which the isocarbonyl group is disordered over two sites. In contrast, [Sm2(N4Et8)(thf)4] reacts with dicobalt octacarbonyl, bis(cyclopentadienyl)tetracarbonyl diiron, and dimanganese decacarbonyl to give the mixed valence species [(thf)2SmII(N4Et8)SmIII(thf)(μ–OC)TM(CO)3]·2PhMe (TM = Co, 4; Fe, 5) and [(thf)2SmII(N4Et8)SmIII(thf)(μ–OC)Mn(CO)4]·1.5PhMe 6. However, both SmII sites of [Sm2(N4Et8)(thf)4] can be oxidized as its reaction with cyclooctatetraene (COT) yields the SmIII species [(thf)SmIII(N4Et8)SmIII(COT)] 7. The analogous EuII reagent, [Eu2(N4Et8)(thf)4] induces C–halogen activation of perfluorodecalin, hexachloroethane, and bromoethane to form the mixed oxidation state species [(thf)2EuII(N4Et8)EuIII(μ–X)]2 (X = F, 8; Cl, 9; Br, 10) despite the use of a sufficient reagent to oxidize both EuII sites. The synthetic potential of the halogenido complexes was illustrated by the reaction of 10 with sodium bis(trimethylsilyl)amide to give the mixed oxidation state [(thf)2EuII(N4Et8)EuIII(N(SiMe3)2)] 11

Reactivity of Bulky Formamidinatosamarium(II or III) Complexes with CO and CS Bonds

The preparation of a new heterobimetallic samarium­(II) formamidinate complex and selected reactions of samarium­(II) complexes and one samarium­(III) formamidinate complex with benzophenone or CS₂ are discussed. Treatment of the tris­(formamidinato)­samarium­(III) complex [Sm­(DippForm)₃] <b>1</b> (DippForm = <i>N</i>,<i>N</i>′-bis­(2,6-diisopropylphenyl)­formamidinate, (CH­(NC₆H₃-^<i>i</i>Pr₂-2,6)₂) with potassium graphite in toluene yielded the dark brown heterobimetallic formamidinatosamarium­(II)/potassium complex [KSm­(DippForm)₃]_<i>n</i> <b>2</b>. Divalent <b>2</b>, a Lewis base solvent free homoleptic species, differs significantly from the related heteroleptic formamidinatosamarium­(II) complex [Sm­(DippForm)₂(thf)₂] <b>3</b> with respect to its constitution, structure, and reactivity toward benzophenone. While <b>2</b> reacts giving complex <b>1</b>, the reaction of <b>3</b> with benzophenone generates the highly unusual [Sm­(DippForm)₂(thf)­{μ-OC­(Ph)(C₆H₅)­C­(Ph)₂O}­Sm­(DippForm)₂] (C₆H₅ = 1,4-cyclohexadiene-3-yl-6-ylidene) <b>4</b>. The formation of <b>4</b> highlights a rare C–C coupling between a carbonyl carbon and the carbon at the para position of a phenyl group of the OCPh₂ fragment. An analogous reaction of [Yb­(DippForm)₂(thf)₂] gives an isostructural complex <b>4Yb</b>. <b>3</b> reacts with carbon disulfide forming a light green dinuclear formamidinatosamarium­(III) complex [{Sm­(DippForm)₂(thf)}₂(μ-η²(C,S):κ­(S′,S″)-SCSCS₂)] <b>5</b> through an unusual C–S coupling induced by an amidinatolanthanoid species giving the thioformylcarbonotrithioate ligand. The trivalent organometallic [Sm­(DippForm)₂(CCPh)­(thf)] complex activates the CO bond of benzophenone by an insertion reaction, forming the light yellow [Sm­(DippForm)₂{OC­(Ph)₂C₂Ph}­(thf)] <b>6</b> as a major product and light yellow unsolvated [Sm­(DippForm)₂{OC­(Ph)₂C₂Ph}] <b>7</b> as a minor product. Molecular structures of complexes (<b>2</b>, <b>4</b>–<b>7</b>) show that κ­(<i>N</i>,<i>N</i>′) bonding between a DippForm and samarium atom exists in all compounds, but in <b>2</b>, DippForm also bridges K and Sm by 1κ­(N):2κ­(N′) bonding and two 2,6-diisopropylphenyl groups are η⁶-bonded to potassium

Synthesis and Structural Characterization of Cationic 5-Hydroxy-1,3-diketonate Stabilized Dinuclear Complexes and Tetranuclear Lanthanoid Clusters

5-Hydroxy-1,3-diketonate ligands have been found to stabilize dimeric complexes and tetrameric lanthanoid clusters dependent on the degree of steric bulk provided by the presence or absence of a methoxy group. Treatment of (R/S,Z)-1′-hydroxy-3-(hydroxy(phenyl)methylene)bi(cyclopentan)-2-one (Hhpb) and the p-methoxyphenyl derivative (Hhmb) with [LnCl2(H2O)6]Cl yields clusters of composition [Ln4(Cl)2(O)(hpb)6]Cl2 (Ln = Nd (1), Ho (2), Tb (3), and Er (4)) and [Ln2(hmb)5]Cl (Ln = La (5), Nd (6), Tb (7), Dy (8), and Er (9)). Single crystal X-ray analysis of the tetranuclear cluster has revealed the lanthanoid core to be in a tetrahedral arrangement around a central μ4-oxygen, bridged by symmetrical chlorides and shrouded in six bridging hpb ligands. The dimeric complexes are stabilized by three bridging and two terminal hmb ligands. In each instance, double or single cationic charges respectively are balanced by chloride anions

Reduction of Carbodiimides by Samarium(II) Bis(trimethylsilyl)amidesFormation of Oxalamidinates and Amidinates through C−C Coupling or C−H Activation

The reaction of [Sm{N(SiMe3)2}2(THF)2] (THF = tetrahydrofuran) with carbodiimides RNCNR (R = Cy, C6H3-2,6-iPr2) led to the formation of dinuclear SmIII complexes via differing C−C coupling processes. For R = Cy, the product [{(Me3Si)2N}2Sm(μ-C2N4Cy4)Sm{N(SiMe3)2}2] (1) has an oxalamidinate [C2N4Cy4]2- ligand resulting from coupling at the central C atoms of two CyNCNCy moieties. In contrast, for R = C6H3-2,6-iPr2, H transfer and an unusual coupling of two iPr methine C atoms resulted in a linked formamidinate complex, [{(Me3Si)2N}2Sm{μ-(RNC(H)N(Ar−Ar)NC(H)NR)}Sm{N(SiMe3)2}2] (2) (Ar−Ar = C6H3-2-iPr-6-C(CH3)2C(CH3)2-6‘-C6H3-2‘-iPr). Analogous reactions of RNCNR (R = Cy, C6H3-2,6-iPr2) with the SmII “ate” complex [Sm{N(SiMe2)3Na] gave 1 for R = Cy, but a novel C-substituted amidinate complex, [(THF)Na{N(R)C(NR)CH2Si(Me2)N(SiMe3)}Sm{N(SiMe3)2}2] (3), for R = C6H3-2,6-iPr2, via γ C−H activation of a N(SiMe3)2 ligand

Four-Membered Group 13 Metal(I) N-Heterocyclic Carbene Analogues: Synthesis, Characterization, and Theoretical Studies

The synthesis, spectroscopic and structural characterization of the monomeric, four-membered group 13 metal(I) heterocycles ([:M{η2-N,N‘-(Ar)NC(NCy2)N(Ar)}], M = Ga or In, Ar = C6H3Pri2-2,6) and an isomeric thallium complex are reported. Theoretical studies on these complexes, which are analogues of four-membered N-heterocyclic carbenes, suggest they should act as good σ-donor ligands