Symmetrization in a phosphinidene-bridged complex to give a diphosphanediyl derivative with metal-centered reactivity

The phosphinidene complex [Mo(2)Cp(μ-κ(1):κ(1),η(5)-PC(5)H(4))(CO)(2)(η(6)-HMes*)] reacts with CO to give the diphosphanediyl derivative [Mo(2){μ-κ(1),η(5):κ(1),η(5)-(C(5)H(4))PP(C(5)H(4))}(η(6)-HMes*)(2)]. The latter compound features unreactive lone electron pairs at phosphorus, which instead contribute to the electronic communication between metal centers via a weak π(PP)-bonding interaction. As a result, this complex displays metal-centered acid-base and redox behavior.     

C-X bond formation and cleavage in the reactions of the ditungsten hydride complex [W2(η5-C5H5)2(H)(μ-PCy2)(CO)2] with small molecules having multiple C-X bonds (X = C, N, O)

Two molecules of C(2)(CO(2)Me)(2) or isocyanides could be added to the title hydride complex under mild conditions to give dienyl-[W(2)Cp(2){μ-η(1),κ:η(2)-C(CO(2)Me)=C(CO(2)Me)C(CO(2)Me)=CH(CO(2)Me)}(μ-PCy(2))(CO)(2)] (Cp = η(5)-C(5)H(5)), diazadienyl-[W(2)Cp(2){μ-κ,η:κ,η-C{CHN(4-MeO-C(6)H(4))}N(4-MeO-C(6)H(4))}(μ-PCy(2))(CO)(2)] or aminocarbyne-bridged derivatives [W(2)Cp(2){μ-CNH(2,6-Me(2)C(6)H(3))}(μ-PCy(2)){CN(2,6-Me(2)C(6)H(3))}(CO)]. In contrast, its reaction with excess (4-Me-C(6)H(4))C(O)H gave the C-O bond cleavage products [W(2)Cp(2){CH(2)(4-Me-C(6)H(4))}(O)(μ-PCy(2))(CO)(2)] and [W(2)Cp(2){μ-η:η,κ-C(O)CH(2)(4-Me-C(6)H(4))}(O)(μ-PCy(2))(CO)].     

Ten-electron coordination and reactivity of an arylphosphinidene ligand

Photochemical decarbonylation of [Mo2Cp2(mu-PR*)(CO)4] (Cp = eta5-C5H5; R* = 2,4,6-C6H2tBu3) gives [Mo2Cp2(mu-kappa1:kappa1,eta6-PR*)(CO)2], which shows the first example of a remarkable 10-electron donor arylphosphinidene ligand which bridges two Mo atoms through its phosphorus atom while being pi-bonded to one Mo center through the six carbon atoms of the aryl ring. This causes a severe pyramidal distortion of the P-bound C atom. The complex adds CO to give [Mo2Cp2(mu-kappa1:kappa1,eta4-PR*)(CO)3], which has an 8-electron donor PR* ligand, and then the parent complex [Mo2Cp2(mu-PR*)(CO)4]. Protonation of [Mo2Cp2(mu-kappa1:kappa1,eta6-PR*)(CO)2] gives the hydride [Mo2Cp2(H)(mu-kappa1:kappa1,eta6-PR*)(CO)2]+, which undergoes P-C bond cleavage and hydride migration, affording the phosphido cation [Mo2Cp2(mu-P)(eta6-R*H)(CO)2]+.     

Mild P4 activation to give an anionic diphosphorus complex with a dual binding ability at a single P site

The anion [Mo(2)Cp(2)(μ-PCy(2))(μ-CO)(2)](-) (1; Li(+) salt) reacts at 290 K with P(4) to give the diphosphorus-bridged complex [Mo(2)Cp(2)(μ-PCy(2))(CO)(2)(μ-κ(2):κ(2)-P(2))](-) (2). The latter reacts with MeI and ClSnPh(3) through a single P atom to give respectively diphosphenyl [Mo(2)Cp(2)(μ-PCy(2))(CO)(2)(μ-κ(2):κ(2)-P(2)Me)] (3) and stannyl [Mo(2)Cp(2)(μ-PCy(2))(CO)(2){μ-κ(2):κ(2)-P(2)(SnPh(3))}] (4) derivatives, with the P-P-Sn angle in 4 being unexpectedly acute [80.3(1)°]. According to density functional theory calculations, this novel nucleophilic behavior of 1 is derived from its anionic nature, thus enabling the P(2) ligand to act in a π-donor-like fashion.     

Indenyl ring slippage in crown thioether complexes [IndMo(CO)2L]+ and C-S activation of trithiacyclononane: experimental and theoretical studies

The macrocycle 1,4,7-trithiacyclononane (ttcn) reacts with [(η(5)-Ind)Mo(CO)(2)(NCMe)(2)](+) (or [(η(5)-Ind)Mo(CO)(2)(κ(2)-dme)](+)) to give [(η(3)-Ind)Mo(CO)(2)(κ(3)-ttcn)](+) as the BF(4)(-) salt (1), but its reaction with [(η(5)-Ind)Mo(CO)(2)(C(3)H(6))(FBF(3))] affords the C-S bond cleavage product [(η(5)-Ind)Mo(CO)(κ(3)-1,4,7-trithiaheptanate)]BF(4) (6), which has been characterised by X-ray crystallography (Ind = C(9)H(7), indenyl). In contrast to ttcn, the macrocycles 1,3,5-trithiane (tt) and 1,4,7,10-tetrathiacyclododecane (ttcd) fail to induce changes in the coordination mode of indenyl: tt and ttcd react with [(η(5)-Ind)Mo(CO)(2)(NCMe)(2)](+) (or [(η(5)-Ind)Mo(CO)(2)(κ(2)-dme)](+)) to give [(η(5)-Ind)Mo(CO)(2)(κ(2)-tt)](+) (2), characterised by X-ray crystallography, and [(η(5)-Ind)Mo(CO)(2)(κ(2)-ttcd)](+) (3), respectively. The cyclopentadienyl (Cp = C(5)H(5)) analogues [(η(5)-CpMo(CO)(2)(κ(2)-tt)](+) (4) and [(η(5)-CpMo(CO)(2)(κ(2)-ttcn)](+) (5) have also been synthesised and 5 characterised by X-ray crystallography. DFT calculations showed that the η(5)-Ind/Cp coordination mode is always the most stable. However, a molecular dynamics study of the macrocycles conformations revealed that the major conformer of ttcn was a chair, which favoured κ(3) coordination. As indenyl complexes undergo slippage with a small barrier (<10 kcal mol(-1)), the kinetically preferred species [(η(3)-Ind)Mo(CO)(2)(κ(3)-ttcn)](+) (1) is the observed one. The conversion to 6 proceeds stepwise, with loss of ethylene followed by loss of CO, as calculated by DFT, with a barrier of 38.7 kcal mol(-1), consistent with the slow uncatalysed reaction.     

Cationic diiron and diruthenium μ-allenyl complexes: synthesis, X-ray structures and cyclization reactions with ethyldiazoacetate/amine affording unprecedented butenolide- and furaniminium-substituted bridging carbene ligands

The novel cationic diiron μ-allenyl complexes [Fe(2)Cp(2)(CO)(2)(μ-CO){μ-η(1):η(2)(α,β)-C(α)(H)=C(β)=C(γ)(R)(2)}](+) (R = Me, 4a; R = Ph, 4b) have been obtained in good yields by a two-step reaction starting from [Fe(2)Cp(2)(CO)(4)]. The solid state structures of [4a][CF(3)SO(3)] and of the diruthenium analogues [Ru(2)Cp(2)(CO)(2)(μ-CO){μ-η(1):η(2)(α,β)-C(α)(H)=C(β)=C(γ)(R)(2)}][BPh(4)] (R = Me, [2a][BPh(4)]; R = Ph, [2c][BPh(4)]) have been ascertained by X-ray diffraction studies. The reactions of 2c and 4a with Br?nsted bases result in formation of the μ-allenylidene compound [Ru(2)Cp(2)(CO)(2)(μ-CO){μ-η(1):η(1)-C(α)=C(β)=C(γ)(Ph)(2)}] (5) and of the dimetallacyclopentenone [Fe(2)Cp(2)(CO)(μ-CO){μ-η(1):η(3)-C(α)(H)=C(β)(C(γ)(Me)CH(2))C(=O)}] (6), respectively. The nitrile adducts [Ru(2)Cp(2)(CO)(NCMe)(μ-CO){μ-η(1):η(2)-C(α)(H)=C(β)=C(γ)(R)(2)}](+) (R = Me, 7a; R = Ph, 7b), prepared by treatment of 2a,c with MeCN/Me(3)NO, react with N(2)CHCO(2)Et/NEt(3) at room temperature, affording the butenolide-substituted carbene complexes [Ru(2)Cp(2)(CO)(μ-CO){μ-η(1):η(3)-C(α)(H)[upper bond 1 start]C(β)C(γ)(R)(2)OC(=O)C[upper bond 1 end](H)] (R = Me, 10a; R = Ph, 10b). The intermediate cationic compound [Ru(2)Cp(2)(CO)(μ-CO){μ-η(1):η(3)-C(α)(H)[upper bond 1 start]C(β)C(γ)(Me)(2)OC(OEt)C[upper bond 1 end](H)](+) (9) has been detected in the course of the reaction leading to 10a. The addition of N(2)CHCO(2)Et/NHEt(2) to 7a gives the 2-furaniminium-carbene [Ru(2)Cp(2)(CO)(μ-CO){μ-η(1):η(3)-C(α)(H)[upper bond 1 start]C(β)C(γ)(Me)(2)OC(OEt)C[upper bond 1 end](H)](+) (11). The X-ray structures of 10a, 10b and [11][BF(4)] have been determined. The reactions of 4a,b with MeCN/Me(3)NO result in prevalent decomposition to mononuclear iron species.     

Molybdenum- and tungsten(II) monometallic 3-(2-pyridyl)pyrazole and bimetallic 3-(2-pyridyl)pyrazolate complexes

Molybdenum and tungsten complexes containing the pypzH (3-(2-pyridyl)pyrazole) ligand as a chelating bidentate are prepared: [Mo(CO)(4)(pypzH)], cis-[MoBr(η(3)-allyl)(CO)(2)(pypzH)], cis-[MoCl(η(3)-methallyl)(CO)(2)(pypzH)], [MI(2)(CO)(3)(pypzH)] (M = Mo, W) from [Mo(CO)(4)(NBD)] or the adequate bis(acetonitrile) complexes. The deprotonation of the molybdenum allyl or methallyl complexes affords the bimetallic complexes [cis-{Mo(η(3)-allyl)(CO)(2)(μ(2)-pypz)}](2) or [cis-{Mo(η(3)-methallyl)(CO)(2)(μ(2)-pypz)}](2) (μ(2)-pypz = μ(2)-3-(2-pyridyl-κ(1)N)pyrazolate-2κ(1)N). The allyl complex was subjected to an electrochemical study, which shows a marked connection between both metallic centres through the bridging pyridylpyrazolates.     

Activation of H-H and H-O bonds at phosphorus with diiron complexes bearing pyramidal phosphinidene ligands

The complex [Fe(2)Cp(2)(μ-PMes*)(μ-CO)(CO)(2)] (Mes* = 2,4,6-C(6)H(2)(t)Bu(3)), which in the solid state displays a pyramidal phosphinidene bridge, reacted at room temperature with H(2) (ca. 4 atm) to give the known phosphine complex [Fe(2)Cp(2)(μ-CO)(2)(CO)(PH(2)Mes*)] as the major product, along with small amounts of other byproducts arising from the thermal degradation of the starting material, such as the phosphindole complex [Fe(2)Cp(2)(μ-CO)(2)(CO){PH(CH(2)CMe(2))C(6)H(2)(t)Bu(2)}], the dimer [Fe(2)Cp(2)(CO)(4)], and free phosphine PH(2)Mes*. During the course of the reaction, trace amounts of the mononuclear phosphide complex [FeCp(CO)(2)(PHMes*)] were also detected, a compound later found to be the major product in the carbonylation of the parent phosphinidene complex, with this reaction also yielding the dimer [Fe(2)Cp(2)(CO)(4)] and the known diphosphene Mes*P═PMes*. The outcome of the carbonylation reactions of the title complex could be rationalized by assuming the formation of an unstable tetracarbonyl intermediate [Fe(2)Cp(2)(μ-PMes*)(CO)(4)] (undetected) that would undergo a fast homolytic cleavage of a Fe-P bond, this being followed by subsequent evolution of the radical species so generated through either dimerization or reaction with trace amounts of water present in the reaction media. A more rational synthetic procedure for the phosphide complex was accomplished through deprotonation of the phosphine compound [FeCp(CO)(2)(PH(2)Mes*)](BF(4)) with Na(OH), the latter in turn being prepared via oxidation of [Fe(2)Cp(2)(CO)(4)] with [FeCp(2)](BF(4)) in the presence of PH(2)Mes*. To account for the hydrogenation of the parent phosphinidene complex it was assumed that, in solution, small amounts of an isomer displaying a terminal phosphinidene ligand would coexist with the more stable bridged form, a proposal supported by density functional theory (DFT) calculations of both isomers, with the latter also revealing that the frontier orbitals of the terminal isomer (only 5.7 kJ mol(-1) above of the bridged isomer, in toluene solution) have the right shapes to interact with the H(2) molecule. In contrast to the above behavior, the cyclohexylphosphinidene complex [Fe(2)Cp(2)(μ-PCy)(μ-CO)(CO)(2)] failed to react with H(2) under conditions comparable to those of its PMes* analogue. Instead, it slowly reacted with HOR (R = H, Et) to give the corresponding phosphinous acid (or ethyl phosphinite) complexes [Fe(2)Cp(2)(μ-CO)(2)(CO){PH(OR)Mes*}], a behavior not observed for the PMes* complex. The presence of BEt(3) increased significantly the rate of the above reaction, thus pointing to a pathway initiated with deprotonation of an O-H bond of the reagent by the basic P center of the phosphinidene complex, this being followed by the nucleophilic attack of the OR(-) anion at the P site of the transient cationic phosphide thus formed. The solid-state structure of the cis isomer of the ethanol derivative was determined through a single crystal X-ray diffraction study (Fe-Fe = 2.5112(8) ?, Fe-P = 2.149(1) ?).     

Reactions of the tetrafluoroborate complex [Mo2Cp2(κ(2)-F2BF2)(μ-PPh2)2(CO)]BF4 with mono- and bidentate ligands having E-H bonds (E = O, S, Se, N, P)

The title compound reacted rapidly with CN(t)Bu at room temperature by displacing the BF(4)(-) ligand and incorporating three molecules of isocyanide to yield the electron-precise complex [Mo(2)Cp(2)(μ-PPh(2))(2)(CN(t)Bu)(3)(CO)](BF(4))(2), which was obtained as a mixture of cis and trans isomers. Reaction with several HER(n) molecules (HER(n) = HSPh, HSePh, H(2)PCy) took place with formal elimination of HBF(4) and spontaneous carbonylation to give the electron-precise cations [Mo(2)Cp(2)(μ-ER(n))(μ-PPh(2))(2)(CO)(2)](+). Reactions with several bidentate ligands (L(2)H) having acidic E-H bonds (2-hydroxypyridine, 2-mercaptopyridine, cathecol, 2-aminophenol, and 2-aminothiophenol) proceeded analogously with deprotonation of these bonds with the preference E = S > O > N. The N,O-donor ligands yielded 32-electron chelate derivatives of the type [Mo(2)Cp(2)(O,N-L(2))(μ-PPh(2))(2)(CO)]BF(4) (L(2) = OC(5)H(4)N, OC(6)H(4)NH(2)), whereas the S,N-donors yielded 34-electron, S-bridged complexes [Mo(2)Cp(2)(μ-S:S,N-L(2))(μ-PPh(2))(2)(CO)]BF(4) [L(2) = SC(5)H(4)N (Mo-Mo = 2.8895(8) ?), SC(6)H(4)NH(2)]. However, reaction with catechol gave a monodentate derivative [Mo(2)Cp(2)(O-OC(6)H(4)OH)(μ-PPh(2))(2)(CO)]BF(4). In contrast, reactions of the title complex with several carboxylic acids and related species (acetic, benzoic, and thioacetic acids, acetamide, thioacetamide, and sodium diethyldithiocarbamate) were insensitive to the nature of the donor atoms and gave in all cases 32-electron chelate derivatives of type [Mo(2)Cp(2)(κ(2)-L(2))(μ-PPh(2))(2)(CO)]BF(4). All of the above cations having Mo-bound OH, NH, or NH(2) groups were easily deprotonated upon reaction with 1,8-diazabicycloundec-7-ene (DBU) or other bases to give neutral complexes which exhibited different coordination motifs depending on the donor atoms, including chelate complexes of the type [Mo(2)Cp(2)(κ(2)-L(2)')(μ-PPh(2))(2)(CO)] (L(2)' = OC(6)H(4)O, OC(6)H(4)NH), the bridged complexes [Mo(2)Cp(2)(μ-S,N:S,N-SC(6)H(4)NH)(μ-PPh(2))(2)] and [Mo(2)Cp(2){μ-S,N-N(S)CMe}(μ-PPh(2))(2)], and the terminal acetylimido complex [Mo(2)Cp(2){N-N(O)CMe}(μ-PPh(2))(2)(CO)].     

CRYSTAL AND MOLECULAR STRUCTURE OF ISOMORPHOUS Cp_2Cr_2(CO)_4(μ-η2-P_2)[M(CO)_5]_2(M=Mo,W)

<正> Cp_2Cr_2(CO)_4(μ-η~2-P_2)C(M(CO)_5]_2(M=Mo(3),W(4)) are isostruc-tural to Cp2Cr2 (CO)4 (μ-η2-P2) [Cr (CO)5]2 (2) and crystallize in space group C2/c (No. 15) with a=18. 553(5),b=10. 462,c=16. 786(2)(2)A ,β=109. 84(1)°,V= 3064. 5(8)A3,Z=4,Mr = 880. 16,F(000) = 1712,and Dc=1.907 g/cm3 for 3,and a -18. 552(6),b= 10. 471 (2),c= 16. 768(2) A, β=109. 77(2)°,V = 3065(1) A3,Z = 4,Mr= 1055. 98,F(000) = 1968,and Dc = 2. 288g/cm3 for 4. This series of complexes share a virtually invariant Cr2(μ-η2-P2) central core with their parent complex Cp2Cr2-(CO)4(μ-η2-P2)(1).The Mo-P (2. 506(1) A) and W-P (2. 511(3) A) distances are longer than the corresponding Cr - P distance (2. 397(1)A) in complex 2 in accordance with the increase in covalent radii of the M atoms.     

Carbon monoxide-induced N-N bond cleavage of nitrous oxide that is competitive with oxygen atom transfer to carbon monoxide as mediated by a Mo(II)/Mo(IV) catalytic cycle

In the presence of CO, facile N-N bond cleavage of N(2)O occurs at the formal Mo(II) center within coordinatively unsaturated mononuclear species derived from Cp*Mo[N((i)Pr)C(Me)N((i)Pr)](CO)(2) (Cp* = η(5)-C(5)Me(5)) (1) and {Cp*Mo[N((i)Pr)C(Me)N((i)Pr)]}(2)(μ-η(1):η(1)-N(2)) (9) under photolytic and dark conditions, respectively, to produce the nitrosyl, isocyanate complex Cp*Mo[N((i)Pr)C(Me)N((i)Pr)](κ-N-NO)(κ-N-NCO) (7). Competitive N-O bond cleavage of N(2)O proceeds under the same conditions to yield the Mo(IV) terminal metal oxo complex Cp*Mo[N((i)Pr)C(Me)N((i)Pr)](O) (3), which can be recycled to produce more 7 through oxygen-atom-transfer oxidation of CO to produce CO(2).     

High yield synthesis and reactivity of a phosphinidene bridged dimolybdenum complex

Protonation of [Mo2Cp2(mu-H)(mu-PHR*)(CO)4] (Cp = eta5-C5H5, R* = 2,4,6-C6H2tBu3) with HBF4.OEt2 gives the hydridophosphinidene complex [Mo2Cp2(mu-H)(mu-PR*)(CO)4]BF4, which is easily deprotonated with H2O to give the known phosphinidene complex [Mo2Cp2(mu-PR*)(CO)4] in 95% yield. Reaction of the latter with I2 gives the unsaturated phosphinidene complex [Mo2Cp2I2(mu-PR*)(CO)2], which exhibits an intermetallic distance of 2.960(2) A. Irradiation of solutions of [Mo2Cp2(mu-PR*)(CO)4] with UV light gives a mixture of the triply bonded [Mo2Cp2(mu-PR*)(mu-CO)2] and the hydridophosphido derivative [Mo2Cp2(mu-H){mu-P(CH2CMe2)C6H2tBu2}(CO)4] as major species. The latter complex results from an intramolecular C-H bond cleavage from a tBu group and has been characterized by spectroscopy and an X-ray study. Irradiation in the presence of HCC(p-tol) results in the insertion of the alkyne into the Mo-P bond to give [Mo2Cp2{mu-eta1:eta2,kappa-C(p-tol)CHPR*}(CO)4] structurally characterized through an X-ray study.     

Lanthanide(III)/actinide(III) differentiation in the cerium and uranium complexes [M(C5Me5)2(L)]0,+ (L=2,2'-bipyridine, 2,2':6',2''-terpyridine): structural, magnetic, and reactivity studies

Treatment of [Ce(Cp*)(2)I] or [U(Cp*)(2)I(py)] with 1 mol equivalent of bipy (Cp*=C(5)Me(5); bipy=2,2'-bipyridine) in THF gave the adducts [M(Cp*)(2)I(bipy)] (M=Ce (1 a), M=U (1 b)), which were transformed into [M(Cp*)(2)(bipy)] (M=Ce (2 a), M=U (2 b)) by Na(Hg) reduction. The crystal structures of 1 a and 1 b show, by comparing the U-N and Ce-N distances and the variations in the C-C and C-N bond lengths within the bidentate ligand, that the extent of donation of electron density into the LUMO of bipy is more important in the actinide than in the lanthanide compound. Reaction of [Ce(Cp*)(2)I] or [U(Cp*)(2)I(py)] with 1 mol equivalent of terpy (terpy=2,2':6',2'-terpyridine) in THF afforded the adducts [M(Cp*)(2)(terpy)]I (M=Ce (3 a), M=U (3 b)), which were reduced to the neutral complexes [M(Cp*)(2)(terpy)] (M=Ce (4 a), M=U (4 b)) by sodium amalgam. The complexes [M(Cp*)(2)(terpy)][M(Cp*)(2)I(2)] (M=Ce (5 a), M=U (5 b)) were prepared from a 2:1 mixture of [M(Cp*)(2)I] and terpy. The rapid and reversible electron-transfer reactions between 3 and 4 in solution were revealed by (1)H NMR spectroscopy. The spectrum of 5 b is identical to that of the 1:1 mixture of [U(Cp*)(2)I(py)] and 3 b, or [U(Cp*)(2)I(2)] and 4 b. The magnetic data for 3 and 4 are consistent with trivalent cerium and uranium species, with the formulation [M(III)(Cp*)(2)(terpy(*-))] for 4 a and 4 b, in which spins on the individual units are uncoupled at 300 K and antiferromagnetically coupled at low temperature. Comparison of the crystal structures of 3 b, 4 b, and 5 b with those of 3 a and the previously reported ytterbium complex [Yb(Cp*)(2)(terpy)] shows that the U-N distances are much shorter, by 0.2 A, than those expected from a purely ionic bonding model. This difference should reflect the presence of stronger electron transfer between the metal and the terpy ligand in the actinide compounds. This feature is also supported by the small but systematic structural variations within the terdentate ligands, which strongly suggest that the LUMO of terpy is more filled in the actinide than in the lanthanide complexes and that the canonical forms [U(IV)(Cp*)(2)(terpy(*-))]I and [U(IV)(Cp*)(2)(terpy(2-))] contribute significantly to the true structures of 3 b and 4 b, respectively. This assumption was confirmed by the reactions of complexes 3 and 4 with the H(.) and H(+) donor reagents Ph(3)SnH and NEt(3)HBPh(4), which led to clear differentiation of the cerium and uranium complexes. No reaction was observed between 3 a and Ph(3)SnH, while the uranium counterpart 3 b was transformed in pyridine into the uranium(IV) compound [U(Cp*)(2){NC(5)H(4)(py)(2)}]I (6), where NC(5)H(4)(py)(2) is the 2,6-dipyridyl(hydro-4-pyridyl) ligand. Complex 6 was further hydrogenated to [U(Cp*)(2){NC(5)H(8)(py)(2)}]I (7) by an excess of Ph(3)SnH in refluxing pyridine. Treatment of 4 a with NEt(3)HBPh(4) led to oxidation of the terpy(*-) ligand and formation of [Ce(Cp*)(2)(terpy)]BPh(4), whereas similar reaction with 4 b afforded [U(Cp*)(2){NC(5)H(4)(py)(2)}]BPh(4) (6'). The crystal structures of 6, 6' and 7 were determined.     

Heterometall-Komplexe mit E6-Liganden (E = P,As)

Heterometallic Complexes with E₆ Ligands (E = P, As) The reaction of [Cp*Co(μ-CO)]₂ 1 with the sandwich complexes [Cp*Fe(η⁵-E₅)] 2 a: E = P, 2 b: E = As in decalin at 190°C affords besides [CpCo₂E₄] 4: E = P, 7: E = As and [CpFe₂P₄] 5 the trinuclear complexes [(Cp*Fe)₂(Cp*Co)(μ-η²-P₂)(μ₃-η^1:2:1-P₂)₂] 3 as well as [(Cp*Fe)₂(Cp*Co)(μ₃-η^2:2:2-As₃)₂] 6 . With [Mo(CO)₅(thf)] 3 and 6 form in a build-up reaction the tetranuclear clusters [(Cp*Fe)₂(Cp*Co)E₆{Mo(CO)₃}] 10: E = P, 11: E = As. 3, 6 and 11 have been further characterized by an X-ray crystal structure determination.     

Mixed phosphine and group-13 metal ligator complexes [(PR3)(a)M(ECp*)b] (M = Mo, Ni; E = Ga, Al; R = C6H5, cyclo-C6H11, CH3)

Treatment of [Mo(N(2))(PMe(3))(5)] with two equivalents GaCp* (Cp* = η(5)-C(5)(CH(3))(5)) leads to the formation of cis-[Mo(GaCp*)(2)(PMe(3))(4)] (1), while AlCp* did not react with this precursor. In addition, [Ni(GaCp*)(2)(PPh(3))(2)] (2a), [Ni(AlCp*)(2)(PPh(3))(2)] (2b), [Ni(GaCp*)(2)(PCy(3))(2)] (3a), [Ni(GaCp*)(2)(PMe(3))(2)] (3b), [Ni(GaCp*)(3)(PCy(3))] (4) and [Ni(GaCp*)(PMe(3))(3)] (5) have been prepared in high yields by a direct synthesis from [Ni(COD)(2)] and stoichiometric amounts of the ligands PR(3) and ECp* (E = Al, Ga), respectively. All compounds have been fully characterized by (1)H, (13)C, and (31)P NMR spectroscopy, elemental analysis and single crystal X-ray diffraction studies.     

Synthesis and reactivity of Ir(I) and Ir(III) complexes with MeNH2, Me2C=NR (R = H, Me), C,N-C6H4{C(Me)=N(Me)}-2, and N,N'-RN=C(Me)CH2C(Me2)NHR (R = H, Me) ligands

Complexes [Ir(Cp*)Cl(n)(NH2Me)(3-n)]X(m) (n = 2, m = 0 (1), n = 1, m = 1, X = Cl (2a), n = 0, m = 2, X = OTf (3)) are obtained by reacting [Ir(Cp*)Cl(mu-Cl)]2 with MeNH2 (1:2 or 1:8) or with [Ag(NH2Me)2]OTf (1:4), respectively. Complex 2b (n = 1, m = 1, X = ClO 4) is obtained from 2a and NaClO4 x H2O. The reaction of 3 with MeC(O)Ph at 80 degrees C gives [Ir(Cp*){C,N-C6H4{C(Me)=N(Me)}-2}(NH2Me)]OTf (4), which in turn reacts with RNC to give [Ir(Cp*){C,N-C6H4{C(Me)=N(Me)}-2}(CNR)]OTf (R = (t)Bu (5), Xy (6)). [Ir(mu-Cl)(COD)]2 reacts with [Ag{N(R)=CMe2}2]X (1:2) to give [Ir{N(R)=CMe2}2(COD)]X (R = H, X = ClO4 (7); R = Me, X = OTf (8)). Complexes [Ir(CO)2(NH=CMe2)2]ClO4 (9) and [IrCl{N(R)=CMe2}(COD)] (R = H (10), Me (11)) are obtained from the appropriate [Ir{N(R)=CMe2}2(COD)]X and CO or Me4NCl, respectively. [Ir(Cp*)Cl(mu-Cl)]2 reacts with [Au(NH=CMe2)(PPh3)]ClO4 (1:2) to give [Ir(Cp*)(mu-Cl)(NH=CMe2)]2(ClO4)2 (12) which in turn reacts with PPh 3 or Me4NCl (1:2) to give [Ir(Cp*)Cl(NH=CMe2)(PPh3)]ClO4 (13) or [Ir(Cp*)Cl2(NH=CMe2)] (14), respectively. Complex 14 hydrolyzes in a CH2Cl2/Et2O solution to give [Ir(Cp*)Cl2(NH3)] (15). The reaction of [Ir(Cp*)Cl(mu-Cl)]2 with [Ag(NH=CMe2)2]ClO4 (1:4) gives [Ir(Cp*)(NH=CMe2)3](ClO4)2 (16a), which reacts with PPNCl (PPN = Ph3=P=N=PPh3) under different reaction conditions to give [Ir(Cp*)(NH=CMe2)3]XY (X = Cl, Y = ClO4 (16b); X = Y = Cl (16c)). Equimolar amounts of 14 and 16a react to give [Ir(Cp*)Cl(NH=CMe2)2]ClO4 (17), which in turn reacts with PPNCl to give [Ir(Cp*)Cl(H-imam)]Cl (R-imam = N,N'-N(R)=C(Me)CH2C(Me)2NHR (18a)]. Complexes [Ir(Cp*)Cl(R-imam)]ClO4 (R = H (18b), Me (19)) are obtained from 18a and AgClO4 or by refluxing 2b in acetone for 7 h, respectively. They react with AgClO4 and the appropriate neutral ligand or with [Ag(NH=CMe2)2]ClO4 to give [Ir(Cp*)(R-imam)L](ClO4)2 (R = H, L = (t)BuNC (20), XyNC (21); R = Me, L = MeCN (22)) or [Ir(Cp*)(H-imam)(NH=CMe2)](ClO4)2 (23a), respectively. The later reacts with PPNCl to give [Ir(Cp*)(H-imam)(NH=CMe2)]Cl(ClO4) (23b). The reaction of 22 with XyNC gives [Ir(Cp*)(Me-imam)(CNXy)](ClO4)2 (24). The structures of complexes 15, 16c and 18b have been solved by X-ray diffraction methods.     

Cluster expansion reactions of group 6 and 8 metallaboranes using transition metal carbonyl compounds of groups 7-9

The reinvestigation of an early synthesis of heterometallic cubane-type clusters has led to the isolation of a number of new clusters which have been characterized by spectroscopic and crystallographic techniques. The thermolysis of [(Cp*Mo)(2)B(4)H(4)E(2)] (1: E = S; 2: E = Se; Cp* = η(5)-C(5)Me(5)) in presence of [Fe(2)(CO)(9)] yielded cubane-type clusters [(Cp*Mo)(2)(μ(3)-E)(2)B(2)H(μ-H){Fe(CO)(2)}(2)Fe(CO)(3)], 4 and 5 (4: E = S; 5: E = Se) together with fused clusters [(Cp*Mo)(2)B(4)H(4)E(2)Fe(CO)(2)Fe(CO)(3)] (8: E = S; 9: E = Se). In a similar fashion, reaction of [(Cp*RuCO)(2)B(2)H(6)], 3, with [Fe(2)(CO)(9)] yielded [(Cp*Ru)(2)(μ(3)-CO)(2)B(2)H(μ-H){Fe(CO)(2)}(2)Fe(CO)(3)], 6, and an incomplete cubane cluster [(μ(3)-BH)(3)(Cp*Ru)(2){Fe(CO)(3)}(2)], 7. Clusters 4-6 can be described as heterometallic cubane clusters containing a Fe(CO)(3) moiety exo-bonded to the cubane, while 7 has an incomplete cubane [Ru(2)Fe(2)B(3)] core. The geometry of both compounds 8 and 9 consist of a bicapped octahedron [Mo(2)Fe(2)B(3)E] and a trigonal bipyramidal [Mo(2)B(2)E] core, fused through a common three vertex [Mo(2)B] triangular face. In addition, thermolysis of 3 with [Mn(2)(CO)(10)] permits the isolation of arachno-[(Cp*RuCO)(2)B(3)H(7)], 10. Cluster 10 constitutes a diruthenaborane analogue of 8-sep pentaborane(11) and has a structural isomeric relationship to 1,2-[{Cp*Ru}(2)(CO)(2)B(3)H(7)].     

Syntheses of highly unsaturated isocyanides via organometallic pathways

The carbon carbon coupling reaction by nucleophilic attack of (CO)(5)Cr(CN-CF=CF(2)) 1 by lithium or Grignard compounds 2a-i yields the isocyanide complexes (CO)(5)Cr(CN-CF=CF-R) 3a-i (a R = CH=CH(2), b R = CH=CF(2), c R = C≡CH, d R = C≡C-SiMe(3), e R = C≡C-Ph, f R = C≡C-C(6)F(4)OMe, g R = C≡C-C(6)H(3)(CF(3))(2), h R = C(6)F(5), i R = C(6)H(3)(CF(3))(2)) as mixtures of E and Z isomers. The dinuclear complexes 5a-c are obtained from the reaction of 1 with the dilithio or dimagnesium compound 4a-c as the Z,Z-, E,Z- and E,E-isomers, respectively. (CO)(5)Cr(CN-CF=CF-C≡C-C≡C-CF=CF-NC)Cr(CO)(5)7 is obtained as a mixture of Z,Z-, Z,E- and E,E-isomers from (CO)(5)Cr(CN-CF=CF-C≡C-H 3d by Eglington-Glaser coupling. (CO)(5)Cr(CN-CF=CF-C≡C-CF=CF-NC)Cr(CO)(5)6 and (CO)(5)Cr(CN-CF=CF-C=C-C≡C-CF=CF-NC)Cr(CO)(5)7 react with octacarbonyldicobalt forming the cluster compounds Z,Z-[{η(2)-μ(2)-(CO)(5)Cr(CN-CF=CF-C≡C-CF=CF-NC)Cr(CO)(5)}Co(2)(CO)(6)] Z,Z-8, E,Z-[{η(2)-μ(2)-(CO)(5)Cr(CN-CF=CF-C≡C-CF=CF-NC)Cr(CO)(5)}Co(2)(CO)(6)] E,Z-8 and E,E-[{η(2)-μ(2)-(CO)(5)Cr(CN-CF=CF-C≡C-CF=CF-NC)Cr(CO)(5)}Co(2)(CO)(6)] E,E-8 and Z,Z-[{η(2)-μ(2)-(CO)(5)Cr(CN-CF=CF-C≡C-C≡C-CF=CF-NC)Cr(CO)(5)}{Co(2)(CO)(6)}(2)] Z,Z-9, E,Z-[{η(2)-μ(2)-(CO)(5)Cr(CN-CF=CF-C≡C-C≡C-CF=CF-NC)Cr(CO)(5)}{Co(2)(CO)(6)}(2)] E,Z-9 and E,E-[{η(2)-μ(2)-(CO)(5)Cr(CN-CF=CF-C≡C-C≡C-CF=CF-NC)Cr(CO)(5)}{Co(2)(CO)(6)}(2)] Z,Z-9, respectively. The crystal and molecular structures of E-3d, Z-3h, Z,Z-8, E,Z-8 and Z,Z-9 were elucidated by single-crystal X-ray crystallography.     

Homoleptic hexa and penta gallylene coordinated complexes of molybdenum and rhodium

The reactions of molybdenum(0) and rhodium(I) olefin containing starting materials with the carbenoid group 13 metal ligator ligand GaR (R = Cp*, DDP; Cp* = pentamethylcyclopentadienyl, DDP = HC(CMeNC(6)H(3)-2,6-(i)Pr(2))(2)) were investigated and compared. Treatment of [Mo(η(4)-butadiene)(3)] with GaCp* under hydrogen atmosphere at 100 °C yields the homoleptic, hexa coordinated, and sterically crowded complex [Mo(GaCp*)(6)] (1) in good yields ≥50%. Compound 1 exhibits an unusual and high coordinated octahedral [MoGa(6)] core. Similarly, [Rh(GaCp*)(5)][CF(3)SO(3)] (2) and [Rh(GaCp*)(5)][BAr(F)] (3) (BAr(F) = B{C(6)H(3)(CF(3))(2)}(4)) are prepared by the reaction of GaCp* with the rhodium(I) compound [Rh(coe)(2)(CF(3)SO(3))](2) (coe = cyclooctene) and subsequent anion exchange in case of 3. Compound 2 features a trigonal bipyramidal [RhGa(5)] unit. In contrast, reaction of excess Ga(DDP) with [Rh(coe)(2)(CF(3)SO(3))](2) does not result in a high coordinated homoleptic complex but instead yields [(coe)(toluene)Rh{Ga(DDP)}(CF(3)SO(3))] (4). The common feature of 2 and 4 in the solid state structure is the presence of short CF(3)SO(2)O···Ga contacts involving the GaCp* or rather the Ga(DDP) ligand. Compounds 1, 2, and 4 have been fully characterized by single crystal X-ray diffraction, variable temperature (1)H and (13)C NMR spectroscopy, IR spectroscopy, mass spectrometry, as well as elemental analysis.     

Proton induced P-H and Mo-H bond activation at the phosphide bridged dimolybdenum complexes [Mo2Cp2(mu-H)(mu-PHR)(CO)4](R = Cy, 2,4,6-C6H2R'3; R'= H, Me, tBu)

The new hydride complexes [Mo2Cp2(mu-H)(mu-PHR)(CO)4] having bulky substituents (R = 2,4,6-C(6)H2tBu3= Mes*, R = 2,4,6-C6H2Me3= Mes) have been prepared in good yield by addition of Li[PHR] to the triply bonded [Mo2Cp2(CO)4] and further protonation of the resulting anionic phosphide complex [Mo2Cp2(mu-PHR)(CO)4]-. Protonation of the Mes* compound with either [H(OEt2)2][B{3,5-C6H3(CF3)2}4] or HBF4.OEt2 gives the cationic phosphinidene complex [Mo2Cp2(mu-H)(mu-PMes*)(CO)4]+ in high yield. In contrast, protonation of the analogous hydride compounds with Mes or Cy substituents on phosphorus give the corresponding unsaturated tetracarbonyls [Mo2Cp2(mu-PHR)(CO)4]+, which are unstable at room temperature and display a cis geometry. Decomposition of the latter give the electron-precise pentacarbonyls [Mo2Cp2(mu-PHR)(mu-CO)(CO)4]+, also displaying a cis arrangement of the metal fragments. In the presence of BF4- as external anion, fluoride abstraction competes with carbonylation to yield the neutral fluorophosphide hydrides [Mo2Cp2(mu-H)(mu-PFR)(CO)4]. Similar results were obtained in the protonation reactions of the hydride compounds having a Ph substituent on phosphorus. In that case, using HCl as protonation reagent gave the chloro-complex [Mo2ClCp2(mu-PHPh)(CO)4] in good yield. The structures and dynamic behaviour of the new compounds are analyzed on the basis of solution IR and 1H, 31P, 19F and 13C NMR data as well as the X-ray studies carried out on [Mo2Cp2(mu-H)(mu-PHMes)(CO)4](cis isomer), [Mo2Cp2(mu-H)(mu-PFMes)(CO)4](trans isomer), [Mo2Cp2(mu-PHCy)(mu-CO)(CO)4](BF4) and [Mo2ClCp2(mu-PHPh)(CO)4].