H-Ge bond activation by tungsten carbonyls: An experimental and theoretical study

The activation of the Ge-H bond and the formation of several hydride complexes, characterized by high-field resonances, have been detected during the ¹H NMR spectroscopy monitoring of the photochemical reaction of Et₃GeH and Et₂GeH₂ with W(CO)₆ and the norbornadiene complex [W(CO)₄(η⁴-nbd)]. The activation of the Ge-H bond of triethylgermane in the photochemical reactions of tungsten(0) complexes has been applied in the hydrogermylation of norbornadiene (nbd), which leads to the formation of endo-triethylgermylnorbornene as the major product. The complex [{W(μ-η²-H-GeEt₂)(CO)₄}₂] has been fully characterized by NMR spectroscopy and by a single-crystal X-ray diffraction study. Evidence for the hydride ligand of the W(μ-η²-H-GeEt₂) group has been provided by ¹H NMR spectroscopy (δ = −9.02, ¹J_H-W = 31 Hz) and by DFT calculations. A DFT study of the structural properties and ¹H NMR chemical shifts of several possible intermediate σ and hydride complexes formed during the photochemical reaction of W(CO)₆ and Et₂GeH₂ has been performed.     

Facile hydrosilylation of norbornadiene by silanes R3SiH and R2SiH2 with molybdenum catalysts

Photochemically activated [Mo(CO)₆] and [Mo(CO)₄(η⁴-nbd)] have been demonstrated to be very effective catalysts for hydrosilylation of norbornadiene (nbd) by tertiary (Et₃SiH, Cl₃SiH) and secondary (Et₂SiH₂ and Ph₂SiH₂) silanes to give 5-silyl-2-norbornene, which under the same reaction conditions transform in ring-opening metathesis polymerization (ROMP) to unsaturated polymers and to a double hydrosilylation product, 2,6-bis(silyl)norbornane. The yield of a particular reaction depends very strongly on the kind of silane involved. The reaction products were identified by means of chromatography (GC–MS) and ¹H and ¹³C NMR spectroscopy. In photochemical reaction of [Mo(CO)₄(η⁴-nbd)] and Ph₂SiH₂ in cyclohexane-d₁₂, η²-coordination of the SiH bond to the molybdenum atom is supported by ¹H NMR spectroscopy due to the detection of two equal-intensity doublets with ²J_HH = 5.4 Hz at δ 6.12 and −5.86 ppm.     

Photochemical reactions of [W(CO)4(η-nbd)] with hydrosilanes: Generation of new hydrido complexes of tungsten and their reactivity

Photolysis of the norbornadiene (nbd) complex [W(CO)₄(η⁴-nbd)] (1) creates a coordinatively unsaturated d⁶ species which interacts with the Si-H bond of tertiary and secondary silanes (Cl₃SiH, Et₃SiH, Et₂SiH₂, Ph₂SiH₂) to yield hydride complexes of varying stability. In reaction of complex 1 with Cl₃SiH, oxidative addition of the Si-H bond to the tungsten(0) center gives the seven-coordinate tungsten(II) complex [WH(SiCl₃)(CO)₃(η⁴-nbd)], which has been fully characterized by NMR spectroscopic methods (¹H, ¹³C{¹H}, 2D ¹H-¹H COSY, 2D ¹³C-¹H HMQC and ²⁹Si{¹H}). Reaction of 1 with Et₃SiH leads to the hydrosilylation of the η⁴-nbd ligand to selectively yield endo-2-triethylsilylnorbornene (nbeSiEt₃). The latter silicon-substituted norbornene gives the unstable pentacarbonyl complex [W(CO)₅(η²-nbeSiEt₃)], whose conversion leads to the initiation of ring-opening metathesis polymerization (ROMP). Reaction of secondary silanes (Et₂SiH₂ and Ph₂SiH₂) with 1 leads to the hydrosilylation and hydrogenation of nbd and the formation of bis(silyl)norbornane and silylnorbornane as the major products. In reaction of 1 and Et₂SiH₂, the intermediate dihydride complex [WH(μ-H-SiEt₂)(CO)_x(η⁴-nbd)] was detected by ¹H and ¹³C NMR spectroscopy. As one of the products formed in photochemical reaction of W(CO)₆ with Ph₂SiH₂, the dinuclear complex [{W(μ-η²-H-SiPh₂)(CO)₄}₂] was identified by NMR spectroscopic methods.     

The Butterfly Complex [{Cp*Cr(CO)3}2(μ,η1:1-P4)] as a Versatile Ligand and Its Unexpected P1/P3 Fragmentation

The versatile coordination behavior of the P₄ butterfly complex [{Cp*Cr(CO)₃}₂(μ,η^1:1-P₄)] ( 1 ) towards Lewis acidic pentacarbonyl compounds of Cr, Mo and W is reported. The reaction of 1 with [W(CO)₄(nbd)] (nbd=norbornadiene) yields the complex [{Cp*Cr(CO)₃}₂(μ₃,η^1:1:1:1-P₄){W(CO)₄}] ( 2 ) in which 1 serves as a chelating P₄ butterfly ligand. In contrast, reactions of 1 with [M(CO)₄(nbd)] (M=Cr ( a ), Mo ( b )) result in the step-wise formation of [{Cp*Cr(CO)₂}₂(μ₃,η^3:1:1-P₄){M(CO)₅}] ( 3 a,b ) and [{Cp*Cr(CO)₂}₂-(μ₄,η^3:1:1:1-P₄){M(CO)₅}₂] ( 4 a,b ) which contain a folded cyclo-P₄ unit. Complex 4 a undergoes an unprecedented P₁/P₃-fragmentation yielding the cyclo-P₃ complex [Cp*Cr(CO)₂(η³-P₃)] ( 5 ) and the as yet unknown phosphinidene complex [Cp*Cr(CO)₂{Cr(CO)₅}₂(μ₃-P)] ( 6 ). The identity of 6 is confirmed by spectroscopic methods and by the in situ formation of [{Cp*Cr(CO)₂(tBuNC)}P{Cr(CO)₅}₂(tBuNC)] ( 7 ). DFT calculations throw light on the bonding situation of the reported products.     

Photochemical reactions of metal carbonyls [M(CO)6 (M = Cr,Mo and W), Re(CO)5Br,Mn(CO)3Cp] with 2-hydroxyacetophenone methanesulfonylhydrazone (apmsh)

Five new complexes, [M(CO)₅(apmsh)] [M = Cr; (1), Mo; (2), W; (3)], [Re(CO)₄Br(apmsh)] (4) and [Mn(CO)₃(apmsh)] (5) have been synthesized by the photochemical reaction of metal carbonyls [M(CO)₆] (M = Cr, Mo and W), [Re(CO)₅Br], and [Mn(CO)₃Cp] with 2-hydroxyacetophenone methanesulfonylhydrazone (apmsh). The complexes have been characterized by elemental analysis, mass spectrometry, f.t.-i.r. and ¹H spectroscopy. Spectroscopic studies show that apmsh behaves as a monodentate ligand coordinating via the imine N donor atom in [M(CO)₅(apmsh)] (1–4) and as a tridentate ligand in (5).     

Synthesis and Crystal Structures of the Molybdenum(II) Complexes with the N,N‐dimethylthiocarbamoyl Containing Ligand: Crystal Structures of [Mo(CO)2(η2‐S2COEt)(η2‐SCNMe2)(PPh3)] and [Mo(CO)2(η2‐S2CNC4H8)(η2‐SCNMe2)(PPh3)]

The reaction of the thiocarbamoyl‐molybdenum complex [Mo(CO)₂(η²‐SCNMe₂)(PPh₃)₂Cl] 1 , with EtOCS2K and C4H8NCS2NH4 in dichloromethane at room temperature yielded the seven coordinated ethyldithiocarbonate thiocarbamoyl‐molybdenum complex [Mo(CO)₂(η²‐S₂COEt)(η²‐SCNMe₂)(PPh₃)] 2 , and the dithiocarbamate thiocarbamoyl‐molybdenum complex [Mo(CO)₂(η²‐S₂CNC₄H₈)(η²‐SCNMe₂)(PPh₃)] 3 . The geometry around the metal atom of compounds 2 and 3 are capped octahedrons as revealed by X‐ray diffraction analyses. The thiocarbamoyl and ethyldithiocarbonate or pyrrolidinyldithiocarbamate ligands coordinate to the molybdenum metal center through the carbon and sulfur and two sulfur atoms, respectively. Structure parameters, NMR, IR and Mass spectra are in agreement with the crystal chemistry of the two compounds.     

Indium monohalide insertion reactions into metal—metal bonds. Crystal structure of [InCl(THF){Mo(CO)3(η-C5H5)}2]

The reaction between InCl and [Mo₂(CO)₆(η-C₅H₅)₂] affords [InCl&{;Mo(CO)₃(η-C₅H₅)&};], 6a which has been characterised as a THF adduct [InCl(THF)&{;Mo(CO)₃(η-C₅H₅)&};₂], 10, by X-ray crystallography. An additional complex, [InCl₂&{;Mo(CO)₃(η-C₅H₅)&};₂]⁻, 11, is also formed in this reaction. Similar products are reported for reactions involving [M₂(CO)₆(η-C₅H₅)₂] (M = Cr, W). The reaction between InCl and [Fe₂(CO)₄(η-C₅H₅)₂] affords [InCl{Fe(CO)₂(η-C₅H₅)}₂], 17, and [InCl₂{Fe(CO)₂(η-C₅H₅)}], whilst that between InI and [Fe₂(CO)₄(η-C₅H₅)₂] affords [InI{Fe(CO)₂(η-C₅H₅)}₂], 19.     

Metal Complexes with Biologically Important Ligands. CLXVI Tetracarbonyl Complexes of Chromium(0) and Molybdenum(0) with Schiff Bases from Pyridine‐2‐carboxaldehyde and α‐Amino Acid Esters as N,N‐Chelate Ligands

The complexes [M(CO)₄(pyridyl‐CH=N‐CHRCO₂R′)] (M = Cr, Mo; R = H, CH₃, CH(CH₃)₂, CH₂CH(CH₃)₂) were obtained by reaction of the Schiff bases from pyridine‐2‐carboxaldehyde and glycine, L‐alanine, L‐valine or L‐leucine esters with the norbornadiene complexes [M(CO)₄(nbd)] and were characterized by IR, ¹H and ¹³C NMR and UV‐vis spectra. The deeply colored complexes exhibit solvatochromism.     

Synthesis of [Ir3Rh(CO)12] and Fluxional Behaviour of Some of Its Substituted Derivatives

The redox condensation of [Ir(CO)₄]^–, [Ir(cod)(THF)₂]⁺, and [Rh(cod)(THF)₂]⁺ (cod = cycloocta-1,5-diene) followed by saturation with CO (1 atm) in THF afforded the first synthetic route to pure [Ir₃Rh(CO)₁₂] ( 1 ). Substitution of CO by monodentate ligands gave [Ir₃Rh(CO)₈(μ₂-CO)₃L] (L = Br^–, 2 ; I^–, 3 ; bicyclo[2.2.1]hept-2-ene, 4 ; PPh₃, 5 ). Clusters 2 – 5 have C_s symmetry with the ligand L bound to the basal Rh-atom in axial position. They are fluxional in solution at the NMR time scale due to two CO scrambling processes: the merry-go-round of basal CO's and changes of basal face. An additional process takes place in 5 above room temperature: the intramolecular migration of PPh₃ from the Rh- to a basal Ir-atom. Substitution of CO by polydentate ligands gave [Ir₃Rh(CO)_7–x(μ₂-CO)₃(η⁴-L)x] (L = bicyclo[2.2.1]hepta-2,5-diene (= norbornadiene; nbd), x = 1, 6 ; L = nbd, x = 2, 13 ; L = cod, x = 1, 7 ; L = cod x = 2, 15 ), [Ir₃Rh(CO)₇(μ₂-CO)₃(η²-diars)] (diars = 1,2-phenylenebis-(dimethylarsine); 8 ), [Ir₃Rh(CO)₇(μ₂-CO)₃(η⁴-L)] (L = methylenebis(diphenylphosphine), bonded to 2 basal Ir-atom ( 9a ) or one Ir- and one Rh-atom ( 9b )), [Ir₃Rh(CO)₆(μ₂-CO)₃(η⁴-nbd)PPh₃] ( 12 ), and [Ir₃Rh(CO)₆(μ₂-CO)₃(μ₃-L)] (L = 1,3,5-trithiane, 10 ; L = CH(PPh₂)₃, 11 ). Complexes 6 – 8 , 9a , 10 , and 11 have C_s symmetry, the others C₁ symmetry. They are fluxional in solution due to CO scrambling processes involving 1, 3, or 4 metal centres as deduced from 2D-EXSY spectra. Comparison of the activation energies of these processes with those of the isostructural Ir₄ and Ir₂Rh₂ compounds showed that substitution of Ir by Rh in the basal face of an Ir₄ compound slows the processes involving 3 or 4 metal centres (merry-go-round and change of basal face), but increases the rate of carbonyl rotation about an Ir-atom.     

Carbonyl (η3-allyl) anions of molybdenum and tungsten

Anionic complexes of the type [M(CO)₂(diket)(η³-allyl)Cl]^? (where M is Mo or W and diket is a β-diketonate group) are readily prepared by the addition of allyl chloride to [M(CO)₄(diket)]^? anions. NMR measurements indicate an equilibrium between two conformers due to rotation of the allyl groups. [M(CO)₅(OC(=O)R)]^? anions also react with allyl chloride to form η³-allyl complex anions. Some structural aspects of both the diketonate and carboxylate derivatives are discussed.     

Binuclear 2,2′-bipyrimidine complexes derived from chromium,molybdenum and tungsten carbonyls

Reaction of 2,2′-bipyrimidine (bpym) with [Mo(CO)₄(diene)] gives [Mo(CO)₄(bpym)], which will react with [M(CO)₄(diene)] to form [MoM(CO)₈(bpym)] (M = Cr, Mo, W). The bipyrimidine complexes are characterised by microanalysis and spectroscopy (IR, ¹H and ¹³C NMR, UV/vis). Reduction of [Mo₂(CO)₈(bpym)] produces an anion in which the unpaired electron is localised on the bridging bpym ligand.     

Photochemical reactions of metal carbonyls [M(CO)6 (M=Cr,Mo, W)] with N,N′ -bis(salicylidene)-1,2-bis- ( o -aminophenoxy)ethane

The complexes [M(CO)₄(η²-H₂L)] [M?=?Cr; 1, Mo; 2, W; 3] have been synthesized by photochemical reactions of VIB metal carbonyls [M(CO)₆] [M?=?Cr,?Mo,?W] with N,N′-bis(salicylidene)-1,2-bis-(o-aminophenoxy)ethane (H₂L) in THF and characterized by elemental analyses, FTIR, ¹H?NMR and mass spectra. The H₂L ligand is coordinated to the central metal as a bidentate ligand via the central azomethine nitrogen atoms in 1–3.     

Reaction of metal carbonyls with 2-hydroxy-1-naphthaldeyde methanesulfonylhydrazone and characterization of the substitution products

Five new complexes, [M(CO)₅(nafmsh)] [M?=?Cr, 1; Mo, 2; W, 3], [Re(CO)₄Br(nafmsh)], 4 and [Mn(CO)₃(nafmsh)], 5 have been synthesized by the photochemical reaction of metal carbonyls [M(CO)₆] (M?=?Cr, Mo, W), [Re(CO)₅Br], and [Mn(CO)₃Cp] with 2-hydroxy-1-naphthaldehyde methanesulfonylhydrazone (nafmsh). The complexes have been characterized by elemental analysis, EI mass spectrometry, FT-IR, and ¹H NMR spectroscopy. The spectroscopic studies show nafmsh is a monodentate ligand coordinating via the imine N donor atom in 1–4 and as a tridentate ligand in 5.     

Molybdenum carbonyl complexes of binucleating pyridine-based ligands

Reaction of [Mo(CO)₄(diene)] with 4,4′-bipyridine (44′B), trans-1,2-bis(2-pyridyl)ethene (2-bpe) and trans-1,2-bis(4-pyridyl)-ethene (4-bpe) gives polymeric [Mo(CO)₄(44′B)]_n, mononuclear cis-[Mo(CO)₄(2-bpe)₂] and binuclear [Mo(CO)₄(4-bpe)]₂ respectively. Reaction of the same ligands with [Mo(CO)₄(bpy)] (bpy is 2,2′-bipyridine) produces the bridged binuclear complexes [{Mo(CO)₃(bpy)}₂(44′B)] and [{Mo(CO)₃(bpy)}₂(4-bpe)]. Products are characterised by microanalysis and spectroscopy (IR, ¹H NMR, UV/vis). Reduction of [{Mo(CO)₃(bpy)}₂(44′B)] produces an anion in which the unpaired electron is localised on the chelating bpy ligand.     

Some reactions of Ni-Mo and Ni-W propargylic cations with nucleophiles

Preliminary reactions of the metal stabilized carbocationic species [(η-C₅H₅)Ni(μ-η²(Ni),η³(Mo)-HC₂CMe₂)Mo(CO)₂(η-C₅H₄Me)]⁺ BF₄⁻ (Ni-Mo) with nucleophiles are reported. The Ni-Mo cationic propargylic complex undergoes nucleophilic attack by sodium methoxide to regenerate the neutral μ-alkyne complex [(η-C₅H₅)Ni{μ-η²,η²-HC₂CMe₂(OMe)}Mo(CO)₂(η-C₅H₄Me)] (Ni-Mo), from which the stabilized carbocation was originally derived by protonation. The new complexes [(η-C₅H₅)Ni{μ-η²,η²-HC₂CMe₂(C₅H₅)}Mo(CO)₂(η-C₅H₄Me)] (Ni-Mo), which exist as an inseparable mixture of 1(c)-1,3- and 2(c)-1,3-cyclopentadienyl isomers, were also obtained. When the Ni-Mo cations were treated with potassium t-butoxide, the alkyne isomers with pendant 1(c)-1,3- and 2(c)-1,3-cyclopentadienyl groups are also formed. The μ-hydroxyalkyne complex [(η-C₅H₅)Ni{μ-η²,η²-HC₂CMe₂(OH)}-Mo(CO)(η-C₅H₄Me)] (Ni-Mo) was also isolated concurrently, and presumably arises from nucleophilic attack of fortuitously present hydroxide ions in the BuO⁻ reagent on the Ni-Mo cation. When NaBH₄ was added to the Ni-Mo propargylic, nucleophilic attack by hydride resulted and the μ-ⁱPrC₂H heterobimetallic complex [(η-C₅H₅)Ni{μ-η²,η²-HC₂Prⁱ}Mo(CO)₂(η-C₅H₄Me)] (Ni-Mo) was recovered in good yield. Small quantities of other side-products were isolated and characterized spectroscopically. Some tantalizing differences in reactivity were observed when the corresponding Ni-W stabilized carbocation was reacted with methoxide ions. When the not fully characterized solid formed by protonating [(η-C₅H₅)Ni(μ-η²,η²-{HC₂CMe₂)(OMe)}W(CO)₂(η-C₅H₄Me)] (Ni-W) was treated with methoxide ions, regioisomers (1(c)-1,3- and 2(c)-1,3-cyclopentadienyl species) of composition [(η-C₅H₅)Ni{μ-η²,η²-HC₂CMe₂(C₅H₅)}W(CO)₂(η-C₅H₄Me)] (Ni-W) were formed. Direct reaction of the pure cation [(η-C₅H₅Niμ-η²,η³-HC₂CMe₂)W(CO)₂(η-C₅H₄Me)]⁺ (Ni-W) with methoxide also generated the same 1(c)-1,3- and 2(c)-1,3-cyclopentadiene-substituted alkyne complexes. Unlike the case with the Ni-Mo complexes, the initial μ-HC₂CMe₂(OMe) species was not regenerated.     

Reactions of Cyclohexyl Isocyanide with η5‐Substituted Cyclo‐pentadienyl MoMo Triply Bonded Complexes. Crystal Structure of [Mo(CO)2(η5‐C5H4CO2CH3)]2(μ‐η2‐CNC6H11)

Reactions of one or two equiv. of cyclohexyl isocyanide in THF at room temperature with Mo?Mo triply bonded complexes [Mo(CO)₂(η⁵‐C₅H₄R)]₂ (R=COCH₃, CO₂CH₃) gave the isocyanide coordinated Mo? Mo singly bonded complexes with functionally substituted cyclopentadienyl ligands, [Mo(CO)₂(η⁵‐C₅H₄R)]₂(μ‐η²‐CNC₆H₁₁) ( 1a , R=COCH₃; 1b , R=CO₂CH₃) and [Mo(CO)₂(η⁵‐C₅H₄R)(CNC₆H₁₁)]₂ ( 2a , R=COCH₃; 2b , R=CO₂CH₃), respectively. Complexes 1a , 1b and 2a , 2b could be more conveniently prepared by thermal decarbonylation of Mo? Mo singly bonded complexes [Mo(CO)₃(η⁵‐C₅H₄R)]₂ (R=COCH₃, CO₂CH₃) in toluene at reflux, followed by treatment of the resulting Mo?Mo triply bonded complexes [Mo(CO)₂(η⁵‐C₅H₄R)]₂ (R=COCH₃, CO₂CH₃) in situ with cyclohexyl isocyanide. While 1a , 1b and 2a , 2b were characterized by elemental analysis and spectroscopy, 1b was further characterized by X‐ray crystallography.     

Structural and bonding aspects of molybdenum tricarbonyl complexes of 2,4,6-tritertiarybutyl-1,3,5-triphosphabenzene,P3C3But3 and some λ3,λ3,λ5- and λ3,λ5,λ5-alkylated derivatives

The molecular structure of the previously reported compound [Mo(CO)₃(η⁶-P₃C₃Bu^t₃)] has been determined by a single-crystal X-ray diffraction study. Syntheses and molecular structures are also described for the structurally related compounds [Mo(CO)₃(η⁵-P₃C₃Bu^t₃)(Me)(Buⁿ)], [Mo(CO)₃(η⁵-P₃C₃Bu^t₃)(H)(Buⁿ)] and [Mo(CO)₃(η⁴-P₃C₃Bu^t₃(Me)(Buⁿ)(H)(O)Li(THF)₃]. Density functional calculations at the B3LYP/cc-pVDZ(-PP) and BP86/cc-pVDZ(-PP) levels have been carried out on the above complexes and the nature of the bonding between the different rings and molybdenum is discussed. ³¹P NMR spectroscopic evidence is presented for the existence of the novel complex [Mo(CO)₃(η⁶-P₃C₃Bu^t₃)PtCl₂(PEt₃)] in which the triphosphabenzene ring acts as an overall 8-electron donor to the two metal centres.     

Synthesis and spectroscopic properties of selenolato- and tellurolato-bridged dimolybdenum(MoMo) complexes [(η5-MeCp)Mo(CO)(μ-EPh)]2 (E = Se,Te)

UV irradiation of the diphenylchalcogenides Ph₂Se₂ or Ph₂Te₂ in the presence of [(η⁵-MeCp)Mo(CO)₃]₂ induces rapid reaction to give the double μ-EPh bridged compounds [(η⁵-MeCp)Mo(CO)₂(μ-EPh)]₂. Subsequent decarbonylation by mild thermolysis in vacuo gives [(η⁵-MeCp)Mo(CO)(μ-SePh)]₂ or [(η⁵-MeCp)Mo(CO)(μ-TePh)₂ in good yields. The new compounds were characterized by elemental analysis, infrared and mass spectra. The mixed Se/ Te bridged complex [(η⁵-MeCp)Mo₂(Co)₄(μ-SePh)(μ-TePh)] was not obtained by UV irradiation of [(η⁵-MeCp)Mo(CO)₃]₂ in the presence of a mixture of Ph₂Se₂ and Ph₂Te₂.     

Comparative studies of the photochemical and thermal reactivities of the molybdenum-molybdenum single bond in [Mo2(η5-C5H5)2(CO)6] and triple bond in [Mo2(η5-C5H5)2(CO)4] towards nitrite and nitrate

Irradiation at λ = 507 and 391 nm of [Mo₂(η⁵-C₅H₅)₂(CO)₆] in a degassed tetrahydrofuran (THF) or THF-MeOH solution containing nitrite gives [Mo(η⁵-C₅H₅)₂NO] and several oxo complexes including [{Mo(η⁵-C₅H₅)(O)₂}₂O] in good yields. The quantum yields for the disappearance of [Mo₂(η⁵-C₅H₅)₂(CO)₆] in the reaction with NO₂⁻ depend on the nitrite concentration, thus suggesting participation of the metal-radical intermediate in the reduction of nitrite. Reactions of [Mo₂(η⁵-C₅H₅)₂(CO)₄] with nitrite or nitrate in the dark give the same nitrosyl and oxo complexes as above. An oxygen atom in nitrite or nitrate is mainly transferred onto the molybdenum atom both in the photochemical and the dark reactions.     

Synthese,Struktur und Reaktivität von η3‐1,2‐Diphosphaallylkomplexen sowie von [{(η5‐C5H5)(CO)2W–Co(CO)3}{μ‐AsCH(SiMe3)2}(μ‐CO)]

Syntheses, Structure and Reactivity of η³‐1,2‐Diphosphaallyl Complexes and [{(η⁵‐C₅H₅)(CO)₂W–Co(CO)₃}{μ‐AsCH(SiMe₃)₂}(μ‐CO)] Reaction of ClP=C(SiMe₂iPr)₂ ( 3 ) with Na[Mo(CO)₃(η⁵‐C₅H₅)] afforded the phosphavinylidene complex [(η⁵‐C₅H₅)(CO)₂Mo=P=C(SiMe₂iPr)₂] ( 4 ) which in situ was converted into the η¹‐1,2‐diphosphaallyl complex [η⁵‐(C₅H₅)(CO)₂Mo{η³‐tBuPPC(SiMe₂iPr)₂] ( 6 ) by treatment with the phosphaalkene tBuP=C(NMe₂)₂. The chloroarsanyl complexes [(η⁵‐C₅H₅)(CO)₃M–As(Cl)CH(SiMe₃)₂] [where M = Mo ( 9 ); M = W ( 10 )] resulted from the reaction of Na[M(CO)₃(η⁵‐C₅H₅)] (M = Mo, W) with Cl₂AsCH(SiMe₃)₂. The tungsten derivative 10 and Na[Co(CO)₄] underwent reaction to give the dinuclear μ‐arsinidene complex [(η⁵‐C₅H₅)(CO)₂W–Co(CO)₃{μ‐AsCH(SiMe₃)₂}(μ‐CO)] ( 11 ). Treatment of [(η⁵‐C₅H₅)(CO)₂Mo{η³‐tBuPPC(SiMe₃)₂}] ( 1 ) with an equimolar amount of ethereal HBF₄ gave rise to a 85/15 mixture of the saline complexes [(η⁵‐C₅H₅)(CO)₂Mo{η²‐tBu(H)P–P(F)CH(SiMe₃)₂}]BF₄ ( 18 ) and [Cp(CO)₂Mo{F₂PCH(SiMe₃)₂}(tBuPH₂)]BF₄ ( 19 ) by HF‐addition to the PC bond of the η³‐diphosphaallyl ligand and subsequent protonation ( 18 ) and/or scission of the PP bond by the acid ( 19 ). Consistently 19 was the sole product when 1 was allowed to react with an excess of ethereal HBF₄. The products 6 , 9 , 10 , 11 , 18 and 19 were characterized by means of spectroscopy (IR, ¹H‐, ¹³C{¹H}‐, ³¹P{¹H}‐NMR, MS). Moreover, the molecular structures of 6 , 11 and 18 were determined by X‐ray diffraction analysis.