Lanthanide versus Actinide Reactivity in the Formation of Sterically Crowded [(C5Me5)3MLn] Nitrile and Isocyanide Complexes

The limits of steric crowding in organometallic metallocene complexes have been examined by studying the synthesis of [(C₅Me₅)₃ML_n] complexes as a function of metal in which L=Me₃CCN, Me₃CNC, and Me₃SiCN. The bis(tert‐butyl nitrile) complexes [(C₅Me₅)₃Ln(NCCMe₃)₂] (Ln=La, 1 ; Ce, 2 ; Pr, 3 ) can be isolated with the largest lanthanide metal ions, La³⁺, Ce³⁺, and Pr³⁺. The Pr³⁺ ion also forms an isolable mono‐nitrile complex, [(C₅Me₅)₃Pr(NCCMe₃)] ( 4 ), whereas for Nd³⁺ only the mono‐adduct [(C₅Me₅)₃Nd(NCCMe₃)] ( 5 ) was observed. With smaller metal ions, Sm³⁺ and Y³⁺, insertion of Me₃CCN into the M? C(C₅Me₅) bond was observed to form the cyclopentadiene‐substituted ketimide complexes [(C₅Me₅)₂Ln{NC(C₅Me₅)(CMe₃)}(NCCMe₃)] (Ln=Sm, 6 ; Y, 7 ). With tert‐butyl isocyanide ligands, a bis‐isocyanide product can be isolated with lanthanum, [(C₅Me₅)₃La(CNCMe₃)₂] ( 8 ), and a mono‐isocyanide product with neodymium, [(C₅Me₅)₃Nd(CNCMe₃)] ( 9 ). Silicon–carbon bond cleavage was observed in reactions between [(C₅Me₅)₃Ln] complexes and trimethylsilyl cyanide, Me₃SiCN, to produce the trimeric cyanide complexes [{(C₅Me₅)₂Ln(μ‐CN)(NCSiMe₃)}₃] (Ln=La, 10 ; Pr, 11 ). With uranium, a mono‐nitrile reaction product, [(C₅Me₅)₃U(NCCMe₃)] ( 12 ), which is analogous to 5 , was obtained from the reaction between [(C₅Me₅)₃U] and Me₃CCN, but [(C₅Me₅)₃U] reacts with Me₃CNC through C? N bond cleavage to form a trimeric cyanide complex, [{(C₅Me₅)₂U(μ‐CN)(CNCMe₃)}₃] ( 13 ).     

On Silylated Oxonium and Sulfonium Ions and Their Interaction with Weakly Coordinating Borate Anions

Attempts have been made to prepare salts with the labile tris(trimethylsilyl)chalconium ions, [(Me₃Si)₃E]⁺ (E=O, S), by reacting [Me₃Si-H-SiMe₃][B(C₆F₅)₄] and Me₃Si[CB] (CB⁻=carborate=[CHB₁₁H₅Cl₆]⁻, [CHB₁₁Cl₁₁]⁻) with Me₃Si-E-SiMe₃. In the reaction of Me₃Si-O-SiMe₃ with [Me₃Si-H-SiMe₃][B(C₆F₅)₄], a ligand exchange was observed in the [Me₃Si-H-SiMe₃]⁺ cation leading to the surprising formation of the persilylated [(Me₃Si)₂(Me₂(H)Si)O]⁺ oxonium ion in a formal [Me₂(H)Si]⁺ instead of the desired [Me₃Si]⁺ transfer reaction. In contrast, the expected homoleptic persilylated [(Me₃Si)₃S]⁺ ion was formed and isolated as [B(C₆F₅)₄]⁻ and [CB]⁻ salt, when Me₃Si-S-SiMe₃ was treated with either [Me₃Si-H-SiMe₃][B(C₆F₅)₄] or Me₃Si[CB]. However, the addition of Me₃Si[CB] to Me₃Si-O-SiMe₃ unexpectedly led to the release of Me₄Si with simultaneous formation of a cyclic dioxonium dication of the type [Me₃Si-μO-SiMe₂]₂[CB]₂ in an anion-mediated reaction. DFT studies on structure, bonding and thermodynamics of the [(Me₃Si)₃E]⁺ and [(Me₃Si)₂(Me₂(H)Si)E]⁺ ion formation are presented as well as mechanistic investigations on the template-driven transformation of the [(Me₃Si)₃E]⁺ ion into a cyclic dichalconium dication [Me₃Si-μE-SiMe₂]₂²⁺.     

Speciation and NMR Spectrometric Studies of Interaction of Di- and Tri-organotin(IV) Moieties with 5′-Guanosine Monophosphate and Guanosine in Aqueous Solution

Potentiometric studies of the interaction of (Me₂Sn)²⁺ and (Me₃Sn)⁺ with 5′-guanosine monophosphate [(5′-HGMP)^2?, abbreviated as (HL-1)^2?] and guanosine [(HGUO), abbreviated as (HL-2)] in aqueous solution (I = 0.1 mol·dm^?3 KNO₃, 298.15 ± 0.1 K) were performed, and the speciation of various complex species was evaluated as a function of pH. The species that exist at physiological pH ~7.0 are Me₂Sn(HL-1)/[Me₂Sn(HL-2)]²⁺ (87.0/88.8 %), [Me₂Sn(HL-1)(OH)]^?/[Me₂Sn(HL-2)(OH)]⁺ (3.0/0 %) and [Me₂Sn(HL-1H_?1)]/[Me₂Sn(HL-2H_?1)]²⁺ (9.4/6.6 %) for 1:1 dimethyltin(IV):5′-guanosine monophosphate/dimethyltin(IV): guanosine systems, whereas for the corresponding 1:2 systems, the species are Me₂Sn(HL-1)/[Me₂Sn(HL-2)]²⁺ (44.0/92.0 %), [Me₂Sn(HL-1H_?1)]/[Me₂Sn(HL-2H_?1)]²⁺ (5.0/6.0 %), Me₂Sn(OH)₂ (49.0/0 %), [Me₂Sn(HL-1)(OH)]^?/[Me₂Sn(HL-2)(OH)]⁺ (1.5/2.0 %), and [Me₂Sn(OH)]⁺ (1.0/0 %). For 1:1 trimethyltin(IV):5′-guanosine monophosphate/trimethyltin(IV):guanosine systems, only [Me₃Sn(HL-1)]^?/[Me₃Sn(HL-2)]⁺ (99.9 %) are found at pH = 7.0, whereas for 1:2 systems, [Me₃Sn(HL-1)]^?/[Me₃Sn(HL-2)]⁺ (49.8/100 %), Me₃Sn(OH) (15.0/0 %) and [Me₃Sn(HL-1)(OH)]^2?/Me₃Sn(HL-2)(OH) (0.2/0 %) are the species found. No polymeric species were detected. Beyond pH = 8.0, significant amounts of [Me₂Sn(OH)]⁺, Me₂Sn(OH)₂, [Me₂Sn(OH)₃]^? and Me₃Sn(OH) are formed. Multinuclear (¹H, ¹³C and ¹¹⁹Sn) NMR studies at different pHs indicated a distorted octahedral geometry for the species Me₂Sn(HL-1)/[Me₂Sn(HL-2)]²⁺ in dimethyltin(IV)-(HL-1)^2?/(HL-2) systems and a distorted trigonal bipyramidal/distorted tetrahedral geometry for the species [Me₃Sn(HL-1)]^?/[Me₃Sn(HL-2)]⁺ in trimethyltin(IV)-(HL-1)^2?/(HL-2) systems.     

Reactions of dimethyl(dimethylsulphoxide)pentamethylcyclopentadienyl-rhodium and -irridum with acids

The complexes [C₅Me₅MMe₂(Me₂SO)] (Ia, M = Rh; Ib, M = Ir) react with p-toluenesulphonic acid in acetonitrile to give [C₅Me₅MMe(Me₂SO)(MeCN)]⁺, (II), and with trifluoroacetic acid to give first [C₅Me₅MMe(Me₂SO)(O₂CCF₃)] and then [C₅Me₅M(Me₂SO)(O₂CCF₃)₂]. Complexes II react with halide (X^?) to give the halomethyl complexes [C₅Me₅MMe(X)(Me₂SO)]. The IR, far-IR, ¹H and ¹³C NMR spectra are all in agreement with structures proposed.     

Übergangsmetall-substituierte Acylphosphane und Phosphaalkene. 22 [1] Insertionen von Hexafluoraceton in die PX-Bindung von Metallophosphanen des Typs (η5-C5Me5)(CO)2M?PX2 (M = Fe,Ru; X = Me3Si,Cl). Strukturbestimmung von (η5-C5Me5)(CO)2Fe?P(SiMe3)C(CF3)2(OSiMe3)

Transition Metal-substituted Acylphosphanes and Phosphaalkenes. 22. Insertions of Hexafluoroacetone into the PX-Bond of Metallophosphanes (η⁵-C₅Me₅)(CO)₂M? PX₂ (M = Fe, Ru; X = Me₃Si, Cl). Structure Determination of (η⁵-C₅Me₅)(CO)₂Fe? P(SiMe₃)C(CF₃)₂(OSiMe₃) Reaction of the metallophosphanes (η⁵-C₅Me₅)(CO)₂M? P(SiMe₃)₂ ( 1a : M = Fe; 1b : M = Ru) with hexafluoroacetone (HFA) afforded the complexes (η⁵-C₅Me₅)(CO)₂M? P(SiMe₃)C(CF₃)₂(OSiMe₃) ( 2a, b ). The attempted synthesis of a metallophosphaalkene from 2a by thermal elimination of hexamethyldisiloxane failed. The acid catalyzed hydrolysis of 2a afforded compound (η⁵-C₅Me₅) · (CO)₂Fe? P(H)C(CF₃)₂(OSiMe₃) ( 3 ). Hexafluoracetone and (η⁵-C₅Me₅)(CO)₂Fe? PCl₂ ( 4 ) under-went reaction to give the metallochlorophosphan (η⁵-C₅Me₅) · (CO)₂Fe? P(Cl)? O? C(CF₃)₂Cl ( 5 ). Constitutions and configurations of the compounds ( 2–5 ) were established by elemental analyses and spectroscopic data (IR, ¹H-, ¹³C, ¹⁹F-, ²⁹Si-, ³¹P-NMR, MS). The molecular structure of 2a was determined by x-ray diffraction analysis.     

Structural Analysis of Zincocenes with Substituted Cyclopentadienyl Rings

New zincocenes [ZnCp′₂] ( 2 – 5 ) with substituted cyclopentadienyl ligands C₅Me₄H, C₅Me₄tBu, C₅Me₄SiMe₂tBu and C₅Me₄SiMe₃, respectively, have been prepared by the reaction of ZnCl₂ with the appropriate Cp′‐transfer reagent. For a comparative structural study, the known [Zn(C₅H₄SiMe₃)₂] ( 1 ), has also been investigated, along with the mixed‐ring zincocenes [Zn(C₅Me₅)(C₅Me₄SiMe₃)] ( 6 ) and [Zn(C₅Me₅)(C₅H₄SiMe₃)] ( 7 ), the last two obtained by conproportionation of [Zn(C₅Me₅)₂] with 5 or 1 , as appropriate. All new compounds were characterised by NMR spectroscopy, and by X‐ray methods, with the exception of 7 , which yields a side‐product ( C ) upon attempted crystallisation. Compounds 5 and 6 were also investigated by ¹³C CPMAS NMR spectroscopy. Zincocenes 1 and 2 have infinite chain structures with bridging Cp′ ligands, while 3 and 4 exhibit slipped‐sandwich geometries. Compounds 5 and 6 have rigid, η⁵/η¹(σ) structures, in which the monohapto C₅Me₄SiMe₃ ligand is bound to zinc through the silyl‐bearing carbon atom, forming a Zn? C bond of comparable strength to the Zn? Me bond in ZnMe₂. Zincocene 5 has dynamic behaviour in solution, but a rigid η⁵/η¹(σ) structure in the solid state, as revealed by ¹³C CPMAS NMR studies, whereas for 6 the different nature of the Cp′ ligands and of the ring substituents of the η¹‐Cp′ group (Me and SiMe₃) have permitted observation for the first time of the rigid η⁵/η¹ solution structure. Iminoacyl compounds of composition [Zn(η⁵‐C₅Me₄R)(η¹‐C(NXyl)C₅Me₄R)] resulting from the reactions of some of the above zincocenes and CNXyl (Xyl=2,6‐dimethylphenylisocyanide) have also been obtained and characterised.     

Organoamido- and aryloxo-lanthanoids. XIII [1]. Organometallic compounds of the lanthanoids. CV [2]. New Lanthanoid(III) Complexes with Pyrazolate Ligands

The complexes Er(Me₂pz)₃(thf) and Ln(Ph₂pz)₃(thf)_n (Ln = Sc, Y, Gd, Er, n = 2; Ln = Lu, n = 3) (Me₂pz^? = 3,5-dimethylpyrazolate, thf = tetrahydrofuran, Ph₂pz^? = 3,5-diphenylpyrazolate) have been prepared by reaction of the lanthanoid metal with bis(pentafluorophenyl)mercury and the pyrazole in thf. The Ln(Ph₂pz)₃(thf)₂ complexes are considered to be eight coordinate with three η²-Ph₂pz ligands. Other lanthanoid pyrazolate complexes, Y(pz)₃(thf)₂, La(Me₂pz)₃(thf), Cp₂Ln(Me₂pz)(thf)_n (Ln = Y, Lu, n = 0; Ln = Lu, n = 1), (C₅Me₅)₂Y(pz)(thf), (C₅Me₅)₂Y(Mepz)(thf), (C₅Me₅)₂Y(Me₂pz)(thf)₂ (pz^? = pyrazolate, Mepz^? = 3-methylpyrazolate, Cp = cyclopentadienyl) have been synthesized by reaction of LnCl₃, Cp₂LnCl, or (C₅Me₅)₂LnCl with the appropriate sodium pyrazolate in thf. The structure of Ln(Me₂pz)₃(thf) (Ln = La or Er) is considered to be a symmetrical dimer with four chelating and two bridging Me₂pz groups, and two bridging thf ligands, whereas the cyclopentadienyl complexes are most likely dimers with bridging pyrazolate groups, and lattice thf of solvation.     

Ionische Strukturen von 4- bzw. 5fach koordiniertem Silicium Neue ionische Festkörperstrukturen von 4- bzw. 5fach koordiniertem Silicium: [Me3Si(NMI)]+Cl−, [Me2HSi(NMI)2]+Cl−, [Me2Si(NMI)3]2+ 2 Cl−· NMI

Ionic Structures of 4- and 5-coordinated Silicon. Novel Ionic Crystal Structures of 4- and 5-coordinated Silicon: [Me₃Si(NMI)]⁺ Cl^?, [Me₂HSi(NMI)₂]⁺ Cl^?, [Me₂Si(NMI)₃]²⁺ 2 Cl^?. NMI Me₃SiCl forms with N-Methylimidazole (NMI) a crystalline 1:1-compound which is stable at room temperature. The X-ray single crystal investigation proves the ionic structure [Me₃Si(NMI)]⁺Cl^? 1 which is the result of the cleavage of the Si? Cl bond and the addition of an NMI-ring. The reaction of Me₂HSiCl with NMI (in the molar ratio of 1:2), under cleavage of the Si? Cl bond and co-ordination of two NMI rings, yields the compound [Me₂HSi(NMI)₂]⁺Cl^? 2 . The analogous reaction of Me₂SiCl₂ with NMI (molar ratio 2:1) leads to a compound which consists of Me₂SiCl₂ and NMI in the molar ratio of 1:2. During the sublimation single crystals of the compound [Me₂Si(NMI)₃]²⁺ 2 Cl^?. NMI 3 are formed.     

Ringkontraktion durch NHC‐induzierte Pnictogen‐Abstraktion

Die Reaktion von [Cp′′′Co(η⁴‐P₄)] ( 1 ) (Cp′′′=1,2,4‐tBu₃C₅H₂) mit ^MeNHC (^MeNHC=1,3,4,5‐tetramethylimidazol‐2‐ylidene) führt über eine NHC‐induzierte Phosphorkationen‐Abstraktion zum Ringkontraktionsprodukt [(^MeNHC)₂P][Cp′′′Co(η³‐P₃)] ( 2 ), welches das erste Beispiel eines anionischen CoP₃‐Komplexes repräsentiert. Solche von NHCs induzierten Ringkontraktionsreaktionen lassen sich ebenfalls auf Tripeldecker‐Sandwich‐Komplexe anwenden. So werden die Komplexe [(Cp*Mo)₂(μ,η^6:6‐E₆)] ( 3 a , 3 b ) (Cp*=C₅Me₅; E=P, As) zu den Komplexen [(^MeNHC)₂E][(Cp*M)₂(μ,η^3:3‐E₃)(μ,η^2:2‐E₂)] ( 4 a , 4 b ) transformiert, wobei 4 b das erste strukturell charakterisierte Beispiel eines NHC‐substituierten As^I‐Kations darstellt. Darüber hinaus führt die Reaktion des Vanadium‐Komplexes [(Cp*V)₂(μ,η^6:6‐P₆)] ( 5 ) mit ^MeNHC zur Bildung der neuartigen Komplexe [(^MeNHC)₂P][(Cp*V)₂(μ,η^6:6‐P₆)] ( 6 ), [(^MeNHC)₂P][(Cp*V)₂(μ,η^5:5‐P₅)] ( 7 ) bzw. [(Cp*V)₂(μ,η^3:3‐P₃)(μ,η^1:1‐P{^MeNHC})] ( 8 ).     

Ring Contraction by NHC‐Induced Pnictogen Abstraction

The reaction of [Cp′′′Co(η⁴‐P₄)] ( 1 ) (Cp′′′=1,2,4‐tBu₃C₅H₂) with ^MeNHC (^MeNHC=1,3,4,5‐tetramethylimidazol‐2‐ylidene) leads through NHC‐induced phosphorus cation abstraction to the ring contraction product [(^MeNHC)₂P][Cp′′′Co(η³‐P₃)] ( 2 ), which represents the first example of an anionic CoP₃ complex. Such NHC‐induced ring contraction reactions are also applicable for triple‐decker sandwich complexes. The complexes [(Cp*Mo)₂(μ,η^6:6‐E₆)] ( 3 a , 3 b ) (Cp*=C₅Me₅; E=P, As) can be transformed to the complexes [(^MeNHC)₂E][(Cp*M)₂(μ,η^3:3‐E₃)(μ,η^2:2‐E₂)] ( 4 a , 4 b ), with 4 b representing the first structurally characterized example of an NHC‐substituted As^I cation. Further, the reaction of the vanadium complex [(Cp*V)₂(μ,η^6:6‐P₆)] ( 5 ) with ^MeNHC results in the formation of the unprecedented complexes [(^MeNHC)₂P][(Cp*V)₂(μ,η^6:6‐P₆)] ( 6 ), [(^MeNHC)₂P][(Cp*V)₂(μ,η^5:5‐P₅)] ( 7 ) and [(Cp*V)₂(μ,η^3:3‐P₃)(μ,η^1:1‐P{^MeNHC})] ( 8 ).     

Übergangsmetall-substituierte acylphosphane und phosphaalkene: XI. Phosphaalkenyl-, disilylphosphido- und diacylphosphidokomplexe des dicarbonylpentamethylcyclopentadienylosmium. Zur kenntnis von [(η5-C5Me5)Os(CO)2]2

The reaction of Os₃(CO)₁₂ with C₅Me₅H in boiling decalin gives the complexes (η⁵-C₅Me₅)(CO)₂OsH and [(η⁵-C₅Me₅)(CO)₂Os]₂. Both compounds were converted into (η⁵-C₅Me₅)(CO)₂OsP(SiMe₃)₂ (III) via the intermediate form (η⁵-C₅-Me₅)(CO)₂OsBr. Complex III was treated with ArC(O)Cl (Ar = Ph, 2,4,6-Me₃C₆H₂) to give mixtures of the phosphaalkenyl complexes (η⁵-C₅Me₅)(CO)₂OsPC(OSiMe₃)(Ar) (IVa, b) and the diacylphosphido complexes (η⁵-C₅Me₅)(CO)₂-OsP[C(O)Ar]₂ (Va, b). Pivaloyl chloride underwent reaction with III to give complex Vc as the only product. The synthesis of the complexes IVa, b includes an E/Z isomerization process.     

[μ‐(Me3SiCH2Sb)5–Sb1,Sb3–{W(CO)5}2] und [{(Me3Si)2CHSb}3Fe(CO)4] – zwei cyclische Komplexe mit Antimon‐Liganden

Syntheses and Crystal Structures of [μ‐(Me₃SiCH₂Sb)₅–Sb¹,Sb³–{W(CO)₅}₂] and [{(Me₃Si)₂CHSb}₃Fe(CO)₄] – Two Cyclic Complexes with Antimony Ligands cyclo‐(Me₃SiCH₂Sb)₅ reacts with [(THF)W(CO)₅] (THF = tetrahydrofuran) to form cyclo‐[μ‐(Me₃SiCH₂Sb)₅–Sb¹,Sb³–{W(CO)₅}₂] ( 1 ). The heterocycle cyclo‐ [{(Me₃Si)₂CHSb}₃Fe(CO)₄] ( 2 ) is formed by an insertion reaction of cyclo‐[(Me₃Si)₂CHSb]₃ and [Fe₂(CO)₉]. The crystal structures of 1 and 2 are reported.     

Reactions of Organic Azides with Half‐sandwich Complexes of Iridium: Preparation of Mono‐ and Bis(imine) Derivatives

Imine complexes [IrCl(η⁵‐C₅Me₅){κ¹‐NH=C(H)Ar}{P(OR)₃}]BPh₄ ( 1 , 2 ) (Ar = C₆H₅, 4‐CH₃C₆H₄; R = Me, Et) were prepared by allowing chloro complexes [IrCl₂(η⁵‐C₅Me₅){P(OR)₃}] to react with benzyl azides ArCH₂N₃. Bis(imine) complexes [Ir(η⁵‐C₅Me₅){κ¹‐NH=C(H)Ar}₂{P(OR)₃}](BPh₄)₂ ( 3 , 4 ) were also prepared by reacting [IrCl₂(η⁵‐C₅Me₅){P(OR)₃}] first with AgOTf and then with benzyl azide. Depending on the experimental conditions, treatment of the dinuclear complex [IrCl₂(η⁵‐C₅Me₅)]₂ with benzyl azide yielded mono‐ [IrCl₂(η⁵‐C₅Me₅){κ¹‐NH=C(H)Ar}] ( 5 ) and bis‐[IrCl(η⁵‐C₅Me₅){κ¹‐NH=C(H)Ar}₂]BPh₄ ( 6 ) imine derivatives. In contrast, treatment of chloro complexes [IrCl₂(η⁵‐C₅Me₅){P(OR)₃}] with phenyl azide C₆H₅N₃ gave amine derivatives [IrCl(η⁵‐C₅Me₅)(C₆H₅NH₂){P(OR)₃}]BPh₄ ( 7 , 8 ). The complexes were characterized spectroscopically (IR, NMR) and by X‐ray crystal structure determination of [IrCl(η⁵‐C₅Me₅){κ¹‐NH=C(H)C₆H₄‐4‐CH₃}{P(OEt)₃}]BPh₄ ( 2b ).     

Synthese,Struktur und Reaktivität des Ferrioarsaalkens [(η5‐C5Me5)(CO)2FeAs=C(Ph)NMe2]

Synthesis, Structure, and Reactivity of the Ferrioarsaalkene [(η⁵‐C₅Me₅)(CO)₂FeAs=C(Ph)NMe₂] Reaction of equimolar amounts of the carbenium iodide [Me₂N(Ph)CSMe]I and LiAs(SiMe₃)₂ · 1.5 THF afforded the thermolabile arsaalkene Me₃SiAs = C(Ph)NMe₂ ( 1 ), which in situ was converted into the black crystalline ferrioarsaalkene [(η⁵‐C₅Me₅)(CO)₂FeAs=C(Ph)NMe₂)] ( 2 ) by treatment with [(η⁵‐C₅Me₅)(CO)₂FeCl]. Compound 2 was protonated by ethereal HBF₄ to yield [(η⁵‐C₅Me₅)(CO)₂FeAs(H)C(Ph)NMe₂]BF₄ ( 3 ) and methylated by CF₃SO₃Me to give [(η⁵‐C₅Me₅)(CO)₂FeAs(Me)C(Ph)NMe₂]‐ SO₃CF₃ ( 4 ). [(η⁵‐C₅Me₅)(CO)₂FeAs[M(CO)_n]C(Ph)NMe₂] ( 5 : [M(CO)_n] = [Fe(CO)₄]; 6 : [Cr(CO)₅]) were isolated from the reaction of 2 with [Fe₂(CO)₉] or [{(Z)‐cyclooctene}Cr(CO)₅], respectively. Compounds 2 – 6 were characterized by means of elemental analyses and spectroscopy (IR, ¹H, ¹³C{¹H}‐NMR). The molecular structure of 2 was determined by X‐ray diffraction analysis.     

Syntheses and structures of doubly tucked-in titanocene complexes with tetramethyl(aryl)cyclopentadienyl ligands

Titanocene–bis(trimethylsilyl)ethyne complexes [Ti(η⁵-C₅Me₄R)₂(η²-Me₃SiCCSiMe₃)], where R=benzyl (Bz, 1a), phenyl (Ph, 1b) and p-fluorophenyl (FPh, 1c), thermolyse at 150–160°C to give products of double C---H activation [Ti(η⁵-C₅Me₄Bz){η³:η⁴-C₅Me₃(CH₂)(CHPh)}] (2a), [Ti(η⁵-C₅Me₄Bz){η³:η⁴-C₅Me₂Bz(CH₂)₂}] (2a′), [Ti(η⁵-C₅Me₄Ph){η³:η⁴-C₅Me₂Ph(CH₂)₂}] (2b), and [Ti(η⁵-C₅Me₄FPh){η³:η⁴-C₅Me₂FPh(CH₂)₂}] (2c). In the presence of 2,2,7,7-tetramethylocta-3,5-diyne (TMOD) the thermolysis affords analogous doubly tucked-in compounds bearing one η³:η⁴-allyldiene and one η⁵-C₅Me₄R ligand having TMOD attached by its C-3 and C-6 carbon atoms to the vicinal methylene groups adjacent to the substituent R (R=Bz (3a), Ph (3b), and FPh (3c)). Compound 3a is smoothly converted into air-stable titanocene dichloride [TiCl₂{η⁵-C₅Me₂Bz(CH₂CH(t-Bu)CH=CHCH(t-Bu)CH₂)}(η⁵-C₅Me₄Bz)] (4a) by a reaction with hydrogen chloride. Yields in both series of doubly tucked-in complexes decrease in the order of substituents: BzPh>FPh. Crystal structures of 1c, 2a, 2b, and 3b have been determined.     

Komplexchemie P-reicher Phosphane und Silylphosphane. VIII. Zur unterschiedlichen Tendenz der Bildung von Chromcarbonyl-Komplexen silylierter-alkylierter Phosphane und Diphosphane

Transition Metal Complexes of P-rich Phosphanes and Silylphosphanes. VIII. Concerning the Different Tendencies of Silylated and Alkylated Phosphanes and Diphosphanes to Form Chromium Carbonyl Complexes The influence of the substituents Me₃Si tBu and Me in phosphanes and diphosphanes on the formation of complex compounds with Cr(CO)₅THF is investigated. tBu(Me₃Si)P? P(SiMe₃)₂ 1 and (tBu)₂P? P(SiMe₃)₂ 2, resp., react with Cr(CO)₅THF 4 at ?18°C by coordinating Cr(CO)₅ to the P(SiMe₃)₂ group to give tBu(Me₃Si)P? P^IV(SiMe₃), · Cr(CO)₅ 1 a, tBu(Me₃Si)P^IV? P^IV(SiMe₃)₂ · Cr(CO)₄ 1b and (tBu)₂P? P^IV(SiMe₃)₂ · Cr(CO)₅ 2a . In the reaction of 1 with 4 using a molar ratio of 1:2 at first 1 a is formed which reacts on to yield completely 1 b. In a mixture of the dissolved compounds (Me₃Si)₃P 5, (tBu)₃P 6 and (tBu)₃P? P(SiMe₃)₂ 2 only 5 and 6 react with Cr(CO)₅THF yielding (Me₃Si)₃P · Cr(CO)₅ and (tBu)₃P · Cr(CO)₅, but 2 does not yet react. In a solution of (Me₃Si)₃P 5, P₂Me₄ 7 and (Me₃Si)₂P? PMe₂ 3 only 5 and 7 react with Cr(CO)₅THF (0.25 to 1.5 equivalents with respect to 3) to give (Me₃Si)₃P · Cr(CO)₅, P₂Me₄ · Cr(CO)₅ and P₂Me₄ · 2Cr(CO)₅. The formation of complexes with Cr(CO)₅THF of the phosphanes 5 and 6 is clearly favoured as compared to the silylated diphosphanes 2 and 3 (not to P₂Me₄); the PR₂ groups (R = tBu, Me in 2 or 3 ) don't have a strong influence.     

Front Cover: A Tetrapodal Penta-Carbene Ligand and Iron(III) Complex (Eur. J. Inorg. Chem. 20/2023)

We report the first tetrapodal pentadentate ligand composed of five N-heterocyclic carbene donors. The proto-ligand [CC_4H5^Me](OTf)₃ (3) is formed in good yields from commercially available reagents. Upon removal of 5 proton equivalents from 3 with bulky non-nucleophilic bases a dianionic penta-carbene framework is provided in good yields as a dilithium complex CC₄^MeLi₂ ( 4 ). Addition of FeCl₃ to a solution of 4 formed in situ provides CC₄^MeFeCl ( 5 ) in moderate yield. Solution-state magnetism measurements of 5 are consistent with a S=1/2 Fe(III) center. The related diamagnetic Fe(II) compound CC₄^MeFe ( 6 ) can be formed through reduction of 5 using KC₈ though poor solubility characteristics have hampered its formation on a preparative scale and full characterization.     

Synthesis of alkene- and alkyne-pentamethylcyclopentadienyl dicarbonyliron complexes via the aquo derivative [Fe(η-C5Me5)(CO)2(OH2)]+BF4-; crystal structure of the ruthenium analogue

[Fe(η-C₅Me₅)(CO)₂(OH₂)]⁺ BF₄^- (2a) reacts with alkenes and alkynes to give the new complexes [Fe(η-C₅Me₅)(CO)₂(alkene)]⁺ BF₄^- and [Fe(η-C₅Me₅)(CO)₂(alkyne)]⁺ BF₄^-. The crystal structure of the ruthenium analogue [Ru(η-C₅Me₅)(CO)₂(OH₂)]⁺ CF₃SO₃^- (2b) is described.     

1,2-Diphosphaferrocene als Liganden in Übergangsmetallkomplexen. Röntgenstrukturanalyse von [(η5-1,3-tBu2C5H3){η5-1,2-[Co2(CO)6]-3,4-(Me3SiO)2-5-(Me3Si)P2C3}]

1,2-Diphosphaferrocenes as Ligands in Transition Metal Complexes. X-Ray Structure Analysis of [(η⁵-1,3-tBu₂C₅H₃){η⁵-1,2-[Co₂(CO)₆]-3,4-(Me₃SiO)₂-5-(Me₃Si)P₂C₃}] Reaction of metallo-1,2-diphosphapropene (η⁵-tBuC₅H₄)(CO)₂Fe? P(SiMe₃)? P?C(SiMe₃)₂ with (Z-cyclooctene)Cr(CO)₅ afforded the pentacarbonylchromium adduct of a 1,2-diphosphaferrocene [(η⁵-tBuC₅C₅H₄){η⁵-1-[Cr(CO)₅]-3,4-(Me₃SiO)₂-5-(Me₃Si)P₂C₃}Fe] ( 1 c ). Diphosphaferrocene [(η⁵-tBuC₅H₄){η⁵-3,4-(Me₃SiO)₂-5-(Me₃Si)P₂C₃}Fe] ( 2 c ) was formed when (η⁵-tBuC₅H₄)(CO)₂FeBr was treated with (Me₃Si)₂P? P?C(SiMe₃)₂ in toluene at 60°C. Photolysis of molybdenum- and tungsten hexacarbonyl in the presence of [(η⁵-1,3-tBu₂C₅H₃){η⁵-3,4-(Me₃SiO)₂-5-(Me₃Si)P₂C₃}Fe] ( 2 b ) gave the pentacarbonylmetal adducts 8 (M = Mo) and 9 (M = W), respectively. A corresponding manganese derivative resulted from the photochemical reaction of 2 b and (MeC₅H₄)Mn(CO)₃. Treatment of 2 b with Co₂(CO)₈ yielded trinuclear [(η⁵-1,3-tBu₂C₅H₃){η⁵-1,2-[Co₂(CO)₆]-3,4-(Me₃SiO)₂-5-(Me₃Si)P₂C₃}Fe] ( 11 ). Constitution and configuration of compounds 1 c, 2 c, 8 – 11 were determined by elemental analyses and spectra (IR, ¹H-, ¹³C-, ³¹P-NMR, MS). In addition the molecular structure of 11 was established by single crystal X-ray analysis.     

Unsymmetrische(Rh—Rh)-zweikernkomplexe mit 34 valenzelektronen: Synthese und eigenschaften von C5Me5(L)Rh(μ-CO)2RhC5Me5

[C₅Me₅Rh(μ-co)]₂ reacts with phosphines (PMe₂H, PMe₃) and trimethylphosphite to give the binuclear complexes C₅Me₅(L)Rh(μ-CO)₂RhC₅Me₅ which have been characterised by elemental analyses, mass spectra,¹H and ³¹P NMR data. They are surprisingly inert toward an excess of L and do not react to give the mononuclear compounds C₅Me₅Rh(CO)L. These are obtained in good yields from C₅Me₅Rh(CO)₂ and L where L is PMe₂H, P(OMe)₃, PEt₃, P(OEt)₃ and PMe₂Ph.