Synthesis and Spectroscopic Characterization of Two Different Types of Heterobimetallic Glycolate Complexes of Niobium(V)

An entirely new class of heterobimetallic homoleptic glycolate complexes of the type Nb(OGO)₃{Ta(OGO)₂} [where G=CMe₂CH₂CH₂CMe₂ (G¹) (3); CMe₂CH₂ CHMe(G²) (4); CHMeCHMe (G³) (5); CH₂CMe₂CH₂ (G⁴) (6); CMe₂CMe₂(G⁵) (7); CH₂CHMeCH₂ (G⁶) (8); CH₂CEt₂CH₂ (G⁷) (9); CH₂CMe(Prⁿ)CH₂ (G⁸) (10)] have been prepared by the reactions of Nb(OGO)₂(OGOH) [G=G¹ (1a); G² (1b); G³ (1c); G⁴ (1d); G⁵ (1e); G⁶ (1f); G⁷ (1g); G⁸ (1h)] with Ta(OGO)₂ (OPrⁱ) (G=G¹ (2a); G² (2b); G³ (2c); G⁴ (2d); G⁵ (2e) G⁶ (2f); G⁷ (2g); G⁸ (2h). In addition to the novel derivatives (2)–(10), our earlier investigations on heterobimetallic glycolate-alkoxide derivatives have been extended to derivatives of the type Nb(OGO) [where M=A1 n=3, G=G³ (11);G⁴ (12); G⁶ (13) G⁷ (14); G^s (15); G⁹=CH₂CH₂CH₂ (16) and M=Ti (n=4, G=G⁴) (17), Zr(n=4,G=G⁴) (18)], which are conveniently prepared by the reactions of metalloligands Nb(OGO)₂(OGOH) [G=G³ (1c); G⁴ (1d); G⁶ (1f); G⁷ (1g); G⁸ (1h); G⁹ (1i)] with different metal alkoxides. All of these new complexes have been characterized by elemental analyses, molecular weight determinations, and spectroscopic (I.r. and ¹H, ²⁷Al-n.m.r.) studies. Structural features of the new derivatives have been elucidated on the basis of molecular weight and spectroscopic data.     

Homometallic glycolates containing hydroxyl functionality for anchoring another metal: synthesis and characterization of heterometallic alkoxide–glycolates of Ti and Zr incorporating Al and Nb

Reaction of Ti(OPrⁱ)₄ with 2-methyl-2,4-pentanediol [HOGOH, where G = CMe₂CH₂CH(Me)] in 1?:?3 M ratio under reflux afforded the monomeric [Ti(OGO)(OGOH)₂] (1), which on further reactions with [Al(OPrⁱ)₃] or [Nb(OPrⁱ)₅] in 1?:?1 and 1?:?2 M ratios afforded heterometallic derivatives, [Ti(OGO)₃{M(OPrⁱ)_n?2}] and [Ti(OGO)₃{M(OPrⁱ)_n?1}₂] [where M = Al (n = 3), Nb (n = 5)], respectively. Similar reactions of Zr(OPrⁱ)₄?PrⁱOH with a number of glycols [HOGOH, where G = CH(Me)CH(Me), CMe₂CMe₂, CMe₂CH₂CH(Me)] yielded dimeric [Zr₂(OGO)₂(OGOH)₄]. [Zr₂(OGO)₆{M(OPrⁱ)_n?2}₂] and [Zr₂(OGO)₄(OGOH)₂M(OPrⁱ)_n?2] [M = Al (n = 3), Ti (n = 4), Nb (n = 5)] were prepared by 1?:?2 and 1?:?1 reactions, respectively, of [Zr₂(OGO)₂(OGOH)₄] with Al(OPrⁱ)₃, Ti(OPrⁱ)₄, or Nb(OPrⁱ)₅. Surprisingly, a 1?:?2 reaction of [VO(OPrⁱ)₃] with 2,2-diethyl-1,3-propanediol in benzene followed a different reaction and produced a neutral tetranuclear derivative [V₄(O)₄(μ-OCH₂CEt₂CH₂O)₂(OCH₂CEt₂CH₂O)₄] (18). All of these derivatives were characterized by elemental analysis, molecular weight measurements, FT-IR, and ¹H NMR (and wherever possible, by ²⁷Al or ⁵¹V NMR) spectroscopic studies. The derivatives [Zr₂(OCMe₂CH₂CH(Me)O)₂(OCMe₂CH₂CH(Me)OH)₄] (9 and 18) were additionally characterized by single-crystal X-ray structure analysis.     

Synthesis and characterization of heterobimetallic mixed-ligand complexes containing Zr(μ-OPri)2Al bridging units

Interesting varieties of heterobimetallic mixed-ligand complexes [Zr{M(OPrⁱ) _n }₂ (L)] (where M = Al, n = 4, L = OC₆H₄CH = NCH₂CH₂O (1); M = Nb, n = 6, L = OC₆H₄CH = NCH₂CH₂O (2); M = Al, n = 4, L = OC₁₀H₆CH = NCH₂CH₂O (3); M = Nb, n = 6, L = OC₁₀H₆CH = NCH₂CH₂O (4)), [Zr{Al(OPrⁱ)₄}₂Cl(OAr)] (where Ar = C₆H₃Me₂-2,5 (5); Ar = C₆H₂Me-4-Bu₂-2,6 (6), [Zr{Al(OPrⁱ)₄}₂(OAr)₂] (where Ar = C₆H₃Me₂-2,5 (7); Ar = C₆H₂Me-4-Bu₂-2,6 (8), [Zr{Al(OPrⁱ)₄}₃(OAr)] (where Ar = C₆H₃Me₂-2,5 (9); Ar = C₆H₃Me₂-2,6 (10), [ZrAl(OPrⁱ)_7-n (ON=CMe₂) _n ] (where n = 4 (11); n = 7 (12), [ZrAl₂(OPrⁱ)_10-n (ON=CMe₂) _n ] (where n = 4 (13); n = 6 (14); n = 10 (15) and [Zr{Al(OPrⁱ)₄}₂{ON=CMe(R)} _n Cl_2–n] [where n = 1, R = Me (16); n = 2, R = Me (17); n = 1, R = Et (18); n = 2, R = Et (19)] have been prepared either by the salt elimination method or by alkoxide-ligand exchange. All of these heterobimetallic complexes have been characterized by elemental analyses, molecular weight measurements, and spectroscopic (I.r., ¹H-, and ²⁷Al- n.m.r.) studies.     

Synthesis and Spectroscopic Characterisation of Six-Coordinate Complexes of Oxovanadium(V)

Complexes of the types VO(L)(R-deaH), VO(R-dea)(LH), and VO(L)(OGOH)[L = deprotonated form of N-(1-hydroxyethyl) naphthaldimine; R-dea = deprotonated form of a N-substituted diethanolamine, with R = H or Ph; G = CH₂CH₂, CHMeCHMe, CMe₂CMe₂, CHMeCH₂CMe₂, CMe₂CH₂CH₂CMe₂] have been prepared by the equimolar reactions of VO(OPr ⁱ )₃, LH₂, and an appropriate diethanolamine or glycol in benzene. All of these coloured solid complexes have been characterised by elemental (C, H, N, and V) analyses and by spectroscopic (i.r., electronic, ¹H-, ⁵¹V-n.m.r) studies. The relative lability of the hydroxy group(s) of N-(1-hydroxyethyl)naphthaldiamine, diethanolamine, and glycol has also been investigated.     

O,O′-dialkyl and alkylene dithiophosphate derivatives of silver(I). X-ray crystal structure of [Ag{S2POCH2CMe2CH2O} PPh3]2 · 2H2O

Silver(I) dialkyl/alkylene dithiophosphates of the types [Ag{S₂P(OR)₂}] and [Ag{S₂P(OGO)}] (where R = –Pr ⁿ ; G = –CMe₂CH₂CHMe–, –CH₂CMe₂CH₂–, –CMe₂CMe₂– or –CH₂CH₂CHMe–) have been prepared by treating an aqueous solution of AgNO₃ with ammonia salts of the respective dithiophosphoric acid. The derivatives form 1:1 adducts readily with 2,2-bipyridine or Ph₃P in CH₂Cl₂ solution. These novel complexes have been characterized by elemental analyses, molecular weight measurements and spectral (i.r., ¹H- and ³¹P-n.m.r.) studies. The crystal structure of [Ag{S₂POCH₂CMe₂CH₂O · PPh₃]₂ · 2H₂O exhibits an unsymmetrical attachment of the silver(I) to the ligand moiety.     

Further studies on organonickel compounds: the synthesis of some new alkyl-, acyl- and cyclopentadienyl-derivatives and the crystal structure of trans-[Ni(CH2SiMe3)2(PMe3)2]

The complex [NiCl₂(PMe₃)₂] reacts with one equivalent of mg(CH₂CMe₃)Cl to yield the monoalkyl derivative trans-[Ni(CH₂CMe₃)Cl(PMe₃)₂], which can be carbonylated at room temperature and pressure to afford the acyl [Ni(COCH₂CMe₃)Cl(PMe₃)₂]. Other related alkyl and acyl complexes of composition [Ni(R)(NCS)(PMe₃)₂] (R = CH₂CMe₃, COCH₂CMe₃) and [Ni(R)(η-C₅H₅)L] (L = PMe₃, R = CH₂CMe₃, COCH₂CMe₃; L = PPh₃, R = CH₂CMe₂Ph) have been similarly prepared. Dialkyl derivatives [NiR₂(dmpe)] (R = CH₂SiMe₃, CH₂CMe₂Ph; dmpe = 1,2-bis(dimethylphosphine)ethane, Me₂PCH₂ CH₂PMe₂) have been obtained by phosphine replacement of the labile pyridine and NNN′N′-tetramethylethylenediamine ligands in the corresponding [Ni(CH₂SiMe₃)₂(py)₂] and [Ni(CH₂CMe₂Ph)₂(tmen)] complexes. A single-crystal X-ray determination carried out on the previously reported trimethylphosphine derivative [Ni(CH₂SiMe₃)₂(PMe₃)₂] shows the complex belongs to the orthorhombic space group Pbcn, with a = 14.345(4), b = 12.656(3), c = 12.815(3) Å, Z = 4 and R 0.077 for 535 independent observed reflections. The phosphine ligands occupy mutually trans positions P-Ni-P 146.9(3)° in a distorted square-planar arrangement.     

Synthesis and Characterization of Chlorobis(cyclopentadienyl) Titanium(IV) and Zirconium(IV) O,O’-Dialkyl and Alkylene Dithiophosphates

Abstract

Reactions of O,O′-dialkyl and alkylene dithiophosphoric acids with bis (cyclopentadienyl) titanium(IV) and zirconium (IV) dichloride in a 1:1 molar ratio in refluxing benzene proceeds with elimination of HCl and formation of the substituted derivatives, Cp₂MCl[S₂P(OR)₂] (where R = Et, Pr-n, Pr-i, Bu-i and Ph), Cp₂MCl[S₂POGO] (where G = ?CH₂CMe₂CH₂?, ?CH₂CEt₂CH₂? and ?CMe₂CMe₂?), (M = Ti and Zr). The complexes are dark red and yellow solids, soluble in common organic solvents and monomeric in nature. These have been characterized on the basis of elemental analyses, molecular weight determinations, IR, and NMR (¹H, ¹³C, and ³¹P).

GRAPHICAL ABSTRACT      

Homo- and hetero-bimetallic glycolates and triethanolaminates of niobium

[Nb(OⁱPr)₅] reacts with 2,5-dimethylhexane-2,5-diol (LH₂), 2,3-dimethylbutane-2,3-diol (L¹H₂) and triethanolamine (teaH₃) in different stoichiometric ratios to yield complexes of the types: [Nb(OⁱPr)₃(L)] (1), [Nb(OⁱPr)(L)₂] (2), [Nb(L)₂(LH)] (3), [Nb(L¹)₂(L¹H)] (4) and [Nb(tea)(teaH)] (5). Equimolar reactions of (3), (4) and (5) with Al(OⁱPr)₃, Ti(OⁱPr)₄ and [Ta(OⁱPr)₅] yield novel heterobimetallic isopropoxide-glycolate (6)–(9) and -triethanolaminate (10)–(12) derivatives. Reactions in appropriate molar ratios of (1), (2) and (10) with alkoxyethanols [ROC₂H₄OH; R = Me, Et] and acetylacetone [acacH] give derivatives [(MeOC₂H₄O)₃Nb(L)] (13), [(acac)Nb(L)₂] (14), [Nb(tea)₂{Al(OC₂H₄OMe)₂}] (15), [Nb(tea)₂{Al(OC₂H₄OEt)₂}] (16) and [Nb(tea)₂{Al(acac)₂}] (17). The complexes (6), (8) and (10) on reaction with an excess of t-BuOH give the tert-butoxo analogues (18), (19) and (20), respectively. These new derivatives have been characterized by elemental analyses, spectroscopic studies and molecular weight measurements.     

The trans-Influence in Platinum (II) Complexes. 1H- and 13C-NMR. and X-ray structural studies of tridentate Schiff's base complexes of platinum (II)

¹H- and ¹³C-NMR. data are reported for the complexes [Pt (1) L] and [Pt (2) L]; 1 = OC₆H₄CH ? NCH₂CH₂O, 2 = OC₆H₄CH ? NC₆H₄O; L = PR₃, AsR₃, C ? N (cyclohexyl), DMSO, pyridine, secondary amine. The molecular structures of [Pt (2) (NHEt₂)] (I) and [Pt (2) (PPh₃)] (II) have been determined by X-ray analysis. Relevant bond distances for I: Pt-N (amine) = 2.076 Å, Pt-N (imine) = 2.017 Å, Pt-O = 1.992 Å and 2.002 Å; for II: Pt-P = 2.248 Å, Pt-N = 2.064 Å, Pt-O = 1.964 and 2.005 Å. Both the solid and solution state data are interpreted in terms of differences in the trans influence of the ligand L. The question of metal-ligand d-p π back bonding to the imine is discussed.     

Metal Complexes of Donor-functionalized Fluorinated β-Ketoiminates – Synthesis,Structure, and CVD Application

Six alkali metal complexes of partly-fluorinated, donor-functionalized β-ketoiminate ligands [L¹Li ( 1 ), L¹Na ( 2 ), L¹K ( 3 ), L¹Cs ( 4 ), L¹ = OC(CF₃)CHC(CH₃)NCH₂CH₂OCH₃; L²Li ( 5 ), L²Na ( 6 ), L² = OC(CF₃)CHC(CH₃)NCH₂CH₂N(CH₃)₂] were prepared and structurally characterized. Reactions of L¹Li with PtCl₂ gave the homoleptic Pt complex L¹₂Pt ( 7 ), which was characterized spectroscopically and by single-crystal X-ray diffraction and whose promising application as CVD precursor (chemical vapor deposition) is shown. Polycrystalline, pure Pt films were grown at 500 °C on SiO₂@Si(100) substrates at 10^–3 mbar and characterized by XRD, SEM, AFM, EDX and XPS.     

Substitutions of organopalladium(II) species with benzimidazole derivatives

The [Pd(cod)(cotl)]ClO₄ complex (cod = cycloocta-1,5-diene; cotl = cyclooctenyl, C₁₈H₁₃ ^–) undergoes substitutions with new Schiff base ligands containing benzimidazole L [L = 2-(2-N-n-propylidenephenyl)benzimidazole (L¹); 2-(2-N-i-propylidenephenyl)benzimidazole (L²); 2-(2-N-n-butylidenephenyl)benzimidazole (L³); 2-(2-N-i-butylidenephenyl)benzimidazole (L⁴)]. Facile displacement of cod by L occurs to produce complexes of the type [Pd(cotl)L]ClO₄· nMe₂CO (n= 0; L = L¹, L² or L³; n= 2, L = L⁴). Dihalobridge complexes of the type [Pd(cotl)X]₂(X = Cl or Br) undergo halogen-bridge cleavage with L¹–L⁴ to give mononuclear complexes of the type Pd(cotl)LX · nH₂O (n= 2, X = Cl, L = L¹; n= 0, X = Br, L = L¹; n= 0, X = Cl, L = L²; n= 0, X = Cl or Br, L = L³; n= 0, X = Cl, L = L⁴; n= 2, X = Br, L = L⁴) and a binuclear complex [Pd(cotl)Br]₂L². The complexes were characterised by physical properties, i.r., ¹H- and ¹³C-n.m.r. spectral techniques and by mass spectra. Probable structures have been proposed.     

Mixed Organometallic–Organic Hybrid Assemblies Based on the Diarsene Complex [Cp2Mo2(CO)4(μ,η2-As2)], AgI Salts and N-Donor Organic Molecules

The reaction of the organometallic diarsene complex [Cp₂Mo₂(CO)₄(η²-As₂)] ( 1 ) with Ag[Al{OC(CF₃)₃}₄] (Ag[TEF]) yielded the Ag^I monomer [Ag(η²- 1 )₃][TEF] ( 2 ). This compound exhibits dynamic behavior in solution, which allows directed selective synthesis of unprecedented organometallic–organic hybrid assemblies upon its reaction with N-donor organic molecules by a stepwise pathway, which is supported by DFT calculations. Accordingly, the reaction of 2 with 2,2′-bipyrimidine ( L1 ) yielded the dicationic molecular compound [{(η²- 1 )₂Ag}₂(μ- L1 )][TEF]₂ ( 3 ) or the 1D polymer [{(η²- 1 )Ag}(μ- L1 )]_n[TEF]_n ( 4 ) depending on the ratio of the reactants. However, its reactions with the pyridine-based linkers 4,4′-bipyridine ( L2 ), 1,2-bis(4-pyridyl)ethylene ( L3 ) and 1,2-bis(4-pyridyl)ethyne ( L4 ) allowed the formation of the 2D polymers [{(η²- 1 )Ag}₂(μ- Lx )₃]_n[TEF]_2n [ Lx=L2 ( 5 ), L3 ( 6 ), L4 ( 7 ), respectively]. Additionally, this concept was extended to step-by-step one-pot reactions of 1 , [Ag(CH₃CN)₃][Al{OC(CF₃)₂(CCl₃)}₄] ([Ag(CH₃CN)₃][TEF^Cl]) and linkers L2 – L4 to produce the 2D polymers [{(η²- 1 )Ag}₂(μ, Lx )₃]_n[TEF^Cl]_2n [ Lx = L2 ( 8 ), L3 ( 9 ), L4 ( 10 ), respectively].     

Front Cover: Small-Molecule Activation by Heteroleptic Metallasilylenes (Eur. J. Inorg. Chem. 2/2023)

We report on reactions of heteroleptic metallasilylenes L¹(Cl)MSiL² (M=Al 1 , Ga 2 , L¹=HC[C(Me)NDipp]₂, Dipp=2,6-ⁱPr₂C₆H₃; L²=PhC(N^tBu)₂) with CO₂, N₂O, and Me₃SiN₃, yielding the corresponding carbonate complexes L¹(Cl)MOSi(CO₃-κ²O,O−)L² (M=Al 3 , Ga 4 ), silanoic esters L¹(Cl)MOSi(O)L² (M=Al 5 , Ga 6 ), and silaimine L¹(Cl)GaSi(NSiMe₃)L² ( 8 ), whereas {L²Si[N(SiMe₃)Al(Cl)C(Me)NDipp][CHC(Me)N(Dipp)]} 7 was formed by C−C bond cleavage of the L¹ ligand. Compounds 3 – 8 were characterized by NMR (¹H, ¹³C) and IR spectroscopy, elemental analysis and single crystal X-ray diffraction.     

Adducts of mononuclear oxomolybdenum(IV)O,O′-dialkyl(alkylene) dithiophosphate complexes with pyridine, 2,2′-bipyridyl and 1, 10-phenanthroline

Summary Equimolar adducts of mononuclear oxomolybdenum(IV)O,O-dialkyl and alkylene dithiophosphates with heterocyclic amines, MoO[S₂P(OR)₂]₂·L (where when R=Et,i-Bu; L=pyridine and when R=Et,n-Pr,i-Bu; L=2,2-bipyridyl, 1,10-phenanthroline) and (where G=CH₂CMe₂CH₂, L=2,2-bipyridyl and when G=CMe₂CMe₂; L=pyridine) have been prepared by reacting the corresponding oxomolybdenum(IV) complexes with an excess of pyridine or with bipyridyl or phenanthroline in a 11 molar ratio.The complexes have been characterized by elemental analyses and molecular weight determinations. Their probable structures are proposed on the basis of i.r. and n.m.r. (¹H,¹³C and³¹P) spectral data, which are consistent with a 6-coordinated octahedral structure for all the base adduct complexes.     

DIALKYL(ARYL) PHOSPHORYL DERIVATIVES OF ALKYLENE DITHIOPHOSPHATES

Dialkyl(aryl) phosphoryl derivatives of alkylene dithiophosphates of general formula (S)SP(O)(OR) ₂ : R = Pr ⁱ , Ph and G = ═CMe ₂ CMe ₂ ═, ═CH ₂ CH ₂ CHMe═, ═CH ₂ CH ₂ CH ₂ CH ₂ ═, ═CMe ₂ CH ₂ CHMe═, and ═CH ₂ CMe ₂ CH ₂ ═; have been synthesized by reacting dialkyl and diaryl phosphoryl chloride with ammonium salts of alkylene dithiophosphates in 1:1 molar ratio in refluxing benzene. The products formed are yellow-colored viscous liquids and white-colored waxy solids; they are soluble in common organic solvents and are nonvolatile, even under reduced pressure. The new compounds have been characterized by elemental analysis, molecular weight measurements and spectroscopic (IR, ¹ H NMR, and ³¹ P NMR)] data.     

CO2 Fixation and Transformation by a Dinuclear Copper Cryptate under Acidic Conditions

CO₂ fixation and transformation by metal complexes continuously receive attention from the viewpoint of carbon resources and environmental concerns. We found that the dinuclear copper(II) cryptate [Cu₂L¹](ClO₄)₄ ( 1 ; L¹=N[(CH₂)₂NHCH₂(m‐C₆H₄)CH₂NH‐(CH₂)₂]₃N) can easily take up atmospheric CO₂ even under weakly acidic conditions at room temperature and convert it from bicarbonate into carbonate monoesters in alcohol solution. The compounds [Cu₂L¹(μ‐O₂COH)](ClO₄)₃ ( 2 ), [Cu₂L¹(μ‐O₂COR)](ClO₄)₃ ( 3 : R=CH₃; 4 : R=C₂H₅; 5 : R=C₃H₇; 6 : R=C₄H₉; 7 : R=C₅H₁₁; 8 : R=CH₂CH₂OH), [Cu₂L¹(μ‐O₂CCH₃)](ClO₄)₃ ( 9 ), and [Cu₂L¹(OH₂)(NO₃)](NO₃)₃ ( 10 ) were characterized by IR spectroscopy and ESI‐MS. The crystal structures of 2 – 6 and 10 were studied by single‐crystal X‐ray diffraction analysis. On the basis of the crystal structures, solution studies, and DFT calculations, a possible mechanism for CO₂ fixation and transformation is given.     

Syntheses,characterization and crystal structures of two square-planar Ni(II) complexes with unsymmetrical tridentate Schiff base ligands and monodentate pseudohalides

Two new square-planar Ni(II) complexes, [NiL¹(NCS)] (1) and [NiL²(N₃)] (2) have been synthesized with the unsymmetrical tridentate Schiff base ligands [(CH₃)₂NCH₂CH₂N=C(CH₃)CH=C(OH)(C₆H₅)], L ¹ H, derived from benzoylacetone and 2-dimethylaminoethylamine and [(CH₃CH₂)₂NCH₂CH₂N=C(CH₃)CH=C(OH)(C₆H₅)], L ² H, derived from benzoylacetone and 2-diethylaminoethylamine, respectively. The complexes have been characterized by elemental analysis, FT-IR, UV-Vis spectroscopy, electrochemical and thermal methods (where applicable). Structures have been established by the single-crystal X-ray diffraction technique which reveals the discrete nature of the complexes in which the metal centers adopt a distorted square planar geometry. Coordination environments of the metal ions in the complexes are satisfied with two different unsymmetrical Schiff base ligands having similar N₂O donor sets and a terminal pseudohalide anion (thiocyanate for 1 and azide for 2).     

Synthesis and Structural Characterization of Some Potassium Complexes of Some Bis(phenolate) Ligands and Some Novel Heterobimetallic Binuclear Arrays Formed with Trivalent Lanthanoid Ions

The structural characterizations of the potassium complexes of a pair of dianionic bis(phenolate) ligands, {L^R = [^?OC₆H₂(2,4‐Bu^t)(6‐CH₂)]₂NCH₂CH₂R} R = NMe₂, OMe, crystallized from 1,2,‐dimethoxyethane (DME) are recorded, showing them to take the binuclear form [K₂L^R(DME)₃]. A pair of neutral binuclear heterobimetallic isotypic complexes are defined with ytterbium(III), with phenol, as sodium salts, of the form [Yb(L^R)(OPh)₂Na(DME)(HOPh)], and a further array with samarium(III), of the (partially protonated) form [Sm(L^OMe)₂Na(OH₂)]. A further complex, [Na(DME)₃][Yb(*L^py)₂], results from an unusual ligand reduction by an ytterbium(II) species to give a new dianionic Schiff base ligand which is coordinated to ytterbium(III) {*L^py = ^?OC₆H₂(2,4‐Bu^t)(6‐CH=N‐CH‐2‐C₆H₄N)}.     

π-Coordination de doubles liaisons azoteazote et carboneazote sur les fragments Cp2NbH et Cp2TaH

The trihydrides Cp₂MH₃ (M = Nb, Ta) react with diphenyl diazomethane giving Cp₂M(diazo)H complexes in which the diazo molecule is η²-N,N-bonded to the metal. When Cp₂TaH₃ is treated with the isonitrile CNCMe₂CH₂C(Me)₃, the complex Cp₂Ta[CH(CN)NR]H (R = CMe₂CH₂CMe₃) is obtained which contains an η²-coordinated CN bond.