Bridging Phosphido Research Articles

Synthesis and structure of the cluster ion pair [Ru3(CO)9[mu-P(NPri2)2]3][Ru6(CO)15(mu 6-C)[mu-P(NPri2)2]]. A theoretical overview of M3(mu-PR2)3 frameworks.

The compound [Ru3(CO)9[mu-P(NPri2)2]3][Ru6(CO)15(mu 6-C)[mu-P(NPri2)2]] (1), obtained via the addition of PCl(NPri2)2 to K2[Ru4(CO)13], crystallizes in the monoclinic space group P2l/c with a = 15.537(8) A, b = 36.151(16) A, c = 19.407(5) A, beta = 91.14(2) degrees, Z = 4, and R = 0.069 for 8006 observed reflections. The unit cell is unusual in that it contains both a typical octahedral Ru6 cluster anion (1a), featuring an encapsulated carbide, and a symmetrical phosphido bridge, in addition to a 50-electron trinuclear cluster cation [Ru3(CO)9[mu-P(NPri2)2]3]+ (1c). The latter, with approximate D3h symmetry, exhibits long Ru-Ru distances (> or = 3.15 A). Among the family of clusters with M3(mu-PR2)3 cores and different numbers of both electrons (TEC) and terminal ligands (LxLyLz), 1c is unique in that it is a 333 stereotype with 50 valence electrons. MO calculations permit us to predict the existence of redox congeners of 1c clusters and related 48e Re3 clusters. This work also presents a summary of the relationships between the electronic and the geometric structures for all known M3LxLyLz(mu-PR2)3 species. The basic stereochemical features are influenced by the total-electron count and, hence, by the degree of M-M bonding, as well as the remarkable flexibility of the phosphido bridging ligands. The mu-PR2 ligands need not necessarily lie in the M3 plane, and a wide range of M-P-M angles (as small as 72 degrees or as large as 133 degrees) have been observed.

The reactions of the anions [Cp2(CO)4Mo2(μ-PRR′)]− (R, R′ = H, Ph) towards chloroarsines and chlorophosphines; synthesis of complexes containing both bridging phosphido and arsenido groups

Deprotonation of the complexes [Cp2(CO)4Mo2(μ-PR1R2)(μ-H)] (R1 and R2 = H or Ph; Cp = cyclopentadienyl) in THF yields the related anions [Cp2(CO)4Mo2(μ-PR1R2)]−. The reactivity of these anions towards Ph2PCl, (EtO)2PCl, Ph2AsCl and Me2AsCl has been investigated. The outcome of the reactions with chlorophosphines depends on the nature of the substituents on the bridging phosphido ligand. Thus reaction of [Cp2(CO)4Mo2(μ-PH2)]− with Ph2PCl yields [Cp2(CO)4Mo2{μ-P(H)PPh2}(μ-H)], whereas the analogous reaction with [Cp2(CO)4Mo2(μ-PPhR)]− yields [Cp2(CO)xMo2(μ-PPh2)(μ-PPhR)] (R = H, x = 4; R = Ph, x = 2). Thermolysis of [Cp2(CO)4Mo2(μ-PPhH)(μ-PPh2)] in toluene yields [Cp2(CO)2Mo2(μ-PPhH)(μ-PPh2)] and [Cp2(CO)(O)Mo2(μ-PPhH)(μ-PPh2)]. In contrast, the reaction of [Cp2(CO)4Mo2(μ-PR1R2)]− with chloroarsines is not dependent on the nature of the R groups either on the phosphorus or arsenic atoms, yielding [Cp2(CO)4Mo2(μ-PR1R2)(μ-AsR32)] in all cases. These complexes are the first example of transition metal compounds containing both a bridging phosphido and a bridging arsenido group. The crystal structures of [Cp2(CO)4Mo2{μ-P(H)PPh2}(μ-H)], [Cp2(CO)4Mo2(μ-PPhH){μ-P(OEt)2}], and [Cp2(CO)4)Mo2(μ-PH2)(μ-AsMe2)] are reported.

Theoretical Overview of Pd(I) and Pt(I) Dimers with Bridging Phosphido Ligand(s).

A review of all of the known structural stereotypes of dimeric Pt(I) or Pd(I) systems with at least one bridging phosphido group is presented. The nature of the direct metal-metal interaction is affected by the number, nature, and disposition of the various coligands. It appears that in some cases a bent M-M bond is by itself a center of nucleophilicity. On the other hand, it is experimentally known that the bridging phosphido ligand is a competing nucleophile, giving rise to an agostic interaction in Pd(2), but not in Pt(2), derivatives. MO theory is used to outline the major electronic features and correlation between different prototypes. Besides a qualitative approach based on the EHMO method, DFT and MP2 methods were used to reproduce the experimental structures and to explore the possibility of unknown tautomers.

Synthesis of a sulfido-capped triiron cluster with bridging phosphido ligands and its reactions with alkynes, phosphites and phosphines †

Treatment of [Fe(CO)5] with Ph2P(SCMe3) at elevated temperature and pressure afforded, as the major product, the sulfur-capped trinuclear iron cluster [Fe3(µ3-S)(µ-PPh2)2(µ-CO)(CO)6] 1, in which two Fe–Fe edges are bridged by phosphido groups and the other by a carbonyl group. Also isolated in low yield from this reaction was the tetranuclear iron complex [{Fe2(µ-PPh2)(CO)6}2(µ4-S2)] 2, which comprises two phosphido-sulfido-bridged diiron fragments linked by an S–S bond. In contrast it has been demonstrated that the reaction of [Fe(CO)5] with Ph2P(SPh) gives the discrete dinuclear complex [Fe2(µ-PPh2)(µ-SPh)(CO)6] in which a sulfur–carbon bond has been retained. The reaction of 1 with organo-phosphites and -phosphines results in preservation of the triiron core and monosubstitution of a carbonyl group to give [Fe3(µ3-S)(µ-PPh2)2(µ-CO)(CO)5(L)] [L = P(OMe)3 3a, P(OPh)3 3b, PPhMe2 3c or PPh3 3d]. On reaction of 1 with terminal alkynes, RCCH [R = Ph or CH2OH], degradation of the trinuclear framework results to give the metallacyclic-bridged bimetallic complexes [Fe2(µ-PPh2CHCRS)(µ-PPh2CHCR)(CO)4] [R = Ph 4a or CH2OH 4b] in which new sulfur–carbon and phosphorus–carbon bonds have formed. In addition, the phosphido-bridged species [Fe2(µ-PPh2)(µ-PPh2CHCPhS)(CO)5] 5 is isolated as a minor product from the reaction of 1 with PhCCH. The structures of complexes 1, 2, 3c and 4a have been determined by single crystal X-ray diffraction analysis and pathways are postulated for the formation of the various products.

Transformation of Dimetallacyclopentanes into β-Substituted Enamine-, Alkylidene-, and α,β-Unsaturated Acyl-Bridged Diiron Complexes

Nucleophilic addition of primary amines RNH2 to C-beta of the diiron allenyl complex [Fe-2(CO)(6)(mu-PPh2)(mu-eta(1):eta(2)-(H)C=C=CH2)] (1) affords the zwitterionic dimetallacyclopentane derivatives [Fe-2(CO)(6)(mu-PPh2)(mu-eta(1):eta(1)-H2C-C(NHR)-CH2)] (R = Pr-i (2a), CH2Ph (2b), C6H11 (2c), Pr-n (2d)). In refluxing toluene, 2a-d rearrange to give the nitrogen-coordinated organodiiron alpha,beta-unsaturated amines [Fe-2(CO)(5)(mu-PPh2)(mu-eta(1)(C):eta(2)(C):eta(1)(N)-(H)C=CCH3(NHR))] (R Pr-i (3a), CH2Ph (3b), C6H11 (3c), Pr-n 3d)) via loss of carbon monoxide, a 1,3-hydrogen migration, and coordination of the beta-amino group. The bridging hydrocarbon in 3a-d adopts a highly unusual exo conformation with respect to the phosphido ligand. Compounds 3a-d are the first diiron beta-substituted enamine complexes to be isolated and structurally characterized. Such compounds have previously been proposed as short-lived intermediates which readily isomerize to their alkylidene-bridged counterparts. Complexes 3a and 3c react with trimethyl phosphite to afford the stable alkylidene valence isomers [Fe-2(CI)(5)(P(OMe)(3))(mu-PPh2)(mu-CHC(CH3)(NHR))] (R = Pr-i (4a), C6H11 (4C)). In contrast, in refluxing toluene, 2a-b react with trimethyl phosphite to give the alpha,beta-unsaturated bridging acyl complexes [Fe-2(CO)(5)(P(OMe)(3))(mu-PPh2)(mu-O=C-CH=CMe(NHR))] (R = P-i (5a), CH2Ph (5b)), which probably result from the formal insertion of carbon monoxide into an alkylidene intermediate. Single-crystal X-ray analyses of 5a and 5b showed the position of substitution to be the iron atom sigma-bonded to the acyl oxygen, trans to the phosphido bridge in 5a and trans to the iron-iron bond in 5b. Variable-temperature (31)p(H-1) and P-31-P-31 2D exchange NMR studies have been.used to examine an exchange process that equilibrates two isomers of 4a and 5b, which differ in the position of the trimethyl phosphite. At low temperature, 4a exists as a 4:1 mixture of these two substitutional isomers, while at room temperature they are in fast exchange, on the NMR time scale. The free energy of activation associated with this exchange (Delta G(273)(double dagger) = 9.5 kcal mol(-1), 4a; Delta G(273 =)(double dagger) 10.4 kcal mol(-1), 5b) is fully consistent with a restricted trigonal twist at the phosphite-substituted iron center. This exchange process also appears to be common to the alkylidene derivative 5b, which has similar (31)p(H-1) line broadening characteristics and free energy of activation. Full structural details of compounds 2a, 3a, 4c, 5a, and 5b are reported.

Octacarbonylbis(μ-cyclohexylphosphanido)manganeserhenium

In contrast to the related homonuclear complexes, the MnReP2 ring is not planar and the C6H11 and H groups at both phosphido bridges are in syn positions.

μ-Chloro-(μ-dicyclohexylphosphanido)bis[tricarbonyl(triphenylphosphine)rhenium

This is the first crystallographically characterized dirhenium carbonyl complex to contain one chloro and one phosphido bridge.

Octacarbonyl(μ-dicyclohexylphosphanido)(μ-trifluoromethylmercury)dirhenium

This is a rare examples of trinuclear rhenium-mercury carbonyl cluster complex containing a bridging phosphido ligand.

Synthesis and NMR spectroscopy of [t-Bu 2PHg( μ-PPh 2)M(CO) 5], M = Cr, Mo, W and X-ray structure for M = Cr, W

The title complexes (M = Cr ( 1), Mo ( 2) and W ( 3)) are prepared in almost quantitative yield from [t-Bu 2PHgN(SiMe 3) 2] and [M(HPPh 2)(CO) 5] or in 70% yield by synproportionation of [Hg(t-Bu 2P) 2] and [Hg{( μ-PPh 2)M(CO) 5} 2]. The compounds are crystalline, air-stable in the solid state but oxygen-sensitive in solution. The solid state structures of 1 and 3 consist of dimers containing four-membered (Hg-P) 2 rings with asymmetric phosphido bridges (252.2(2)pm and 268.9(2)pm for 1). The coordination geometry of Hg is almost planar. According to 31P and 199Hg NMR spectroscopy, the solution structure consists of dimers at 173K, whilst dissociation into monomers occurs at ambient temperature.

A theoretical investigation of classical and non-classical complex molecular structures of Fe 2(CO) n(μ-PR 2)(μ-PR′ 2) ( n = 5, 6) dimers

For the title compounds, three different complex molecular structures exist depending on the size of the bridging phosphido groups. A theoretical analysis based on complete geometry optimizations at the SCF level and various estimations of the influence of the correlation energy shows that the bonding situation in the bridging region is quite different in the three cases. In the “classical” system (CO) 3Fe(μ-PPh 2) 2Fe(CO) 3, with a puckered Fe 2P 2 moiety, the usual bent bond picture is confirmed. For the system (CO) 3Fe(μ-PR 2)(μ-PR′ 2)Fe(CO) 3, with a planar bridging moiety, some direct FeFe σ-bonding as well as π-bonding interaction must be assumed. Finally, in the electron-deficient system (CO) 3Fe(μ-PR 2)(μ-PR′ 2)Fe(CO) 2, which also has a planar bridging unit, a strong direct FeFe double bond acts.

μ-Hydrido-μ-dicyclohexylphosphido-bis[dicyclohexylphosphine(tricarbonyl)rhenium

The title compound, hexacarbonyl-1κ3C,2κ3C-μ-dicyclohexylphosphido-1:2κ2P-bis(dicyclohexylphosphine)-1κP,2κP-μ-hydrido-dirhenium(Re—Re), [Re2H(C12H22P)(C12H23P)2(CO)6], has an Re—Re bond length of 3.2185 (8) A which is symmetrically bridged by a H and a P atom. Two terminal PH(C6H11)2 ligands adopt cis positions with respect to the phosphido bridge and have a mutually trans configuration.

Substitution of chloride in [PtCl 2(PET 3) 2] by the chiral anionic ligand [Mo(CO) 5(PPhH)] − to give mixed platinum-molybdenum compounds and a 31P∗ 1H∗ NMR analysis of their fluxionality. X-ray crystal structure of [PtCl(PEt 3) 2 (μ-PPhH) ∗Mo(CO) 5∗] and trans-[Pt(PEt 3) 2 (μ-PPH) 2 ∗Mo(CO) 5∗ 2

Deprotonation of the primary phosphine complex [Mo(CO) 5(PPhH 2)] generated [Mo(CO) 5(PPhH)] −, a chiral anionic ligand which reacted readily with cis- or trans-[PtCl 2(PEt 3) 2] via facile nucleophilic substitution of one or both chloride ligands to afford trans-[PtCl(PEt 3) 2(μ-PPhH)∗Mo(CO) 5∗] ( 1) and cis- and trans-[Pt(PEt 3) 2(μ-PPhH) 2∗Mo(CO) 5∗ 2] ( 2), respectively. These are rare examples of heterometallic complexes containing primary phosphido bridges. Compound ( 1) can be described either as the square-planar Pt 11 complex with the anionic ligand PPhH∗Mo(CO) 5∗ − or as the PtMo phosphido-bridged dimer trans-[PtCl(PEt 3) 2(μ-PPhH)∗Mo(CO) 5∗]. As a phosphido-bridged heterobimetallic ( 1) possesses an exceptionally large PtPMo angle [120.9(1) °] reflecting the long PtMo nonbonding interaction (4.5 Å). Compound 2 can correspondingly be described either as a phosphido-bridged PtMo 2 trimer or a square-planar arrangement of two neutral PEt 3 and two anionic PPhH∗Mo(CO) 5∗ ligands at Pt. The low-temperature 31P∗ 1H∗ NMR spectrum of 1 showed several ABXY spin systems together with their associated ABXYM ( M = 195 Pt ) counterparts and variable-temperature studies revealed the dynamic interconversion of several rotametric isomers arising from restricted rotation about the PtPμ bond. The 31P∗ 1H∗ NMR spectrum of trans- 2 shows its two possible RR/SS and meso diastereoisomers, the latter existing in clearly identifiable rotameric forms which interconvert slowly at −75°C. We note very different values between 2J( P P) and 1J( 195 Pt P) for the anionic ligands [PPhH∗Mo(CO) 5∗] − and PEt 3, unattributable to bond length variation but which must reflect reduced s-orbital contribution to the PtP bond of the anionic phosphines PPhH∗Mo(CO) 5∗.

μ-Bromo-μ-phosphido-bis(tetracarbonylmanganese) and di-μ-phosphido-bis(tetracarbonylmanganese). Co-crystallization and disorder

Abstract (μ-Br)(μ-PH2)Mn2(CO8) (I) and (μ-PH2)2 · Mn2(CO8) (II) co-crystallize in space group P21/c with a = 9.467(2) Å, b = 12.181(2) Å, c = 13.086(3) Å, β = 109.98(2)°, V = 1418.2(5) Å3. The Mn2(CO)8 part of both molecules occupies the same site, the positions of the bromo and phosphido bridges show positional disorder. Average bond lengths are Mn–Br 2.606(5) Å and Mn–P 2.321(8) Å.

Synthesis, Structure, and Deprotonation of a Mesitylphosphido-Bridged Cyclopentadienylnickel(II) Dimer

The bridging phosphido complex [NiCp(μ-PHMes)]2 (1, Mes = 2,4,6-Me3C6H2) was prepared from NiCp2 and PH2Mes. Deprotonation and methylation of 1 yields (NiCp)2(μ-PHMes)(μ-PMeMes) (4) and [NiCp(μ-PMeMes)]2 (6) via observable anionic phosphinidene intermediates. NMR spectroscopy was used to characterize syn and anti isomers of 1, 4, and 6, and the structures of anti-1a and syn-6b were determined by X-ray crystallography.

Substitution of chloride in [PtCl 2(dppe)] by the chiral anionic ligand [Mo(CO) 5(PPhH)] − : Synthesis and X-ray structure of [Pt(μ-PPhH) 2{Mo(CO) 5} 2(dppe)] and a 31P{ 1H} NMR analysis of its isomeric products and fluxionality

Reaction of the chiral anionic ligand [Mo(CO) 5(PPhH)] − with [PtCl 2(L-L)] affords the neutral trimetallic monophosphido bridged complexes [Pt(μ-PPhH) 2{Mo-(CO) 5} 2(L-L)] (L-L = dppe, Ph 2PCH 2CH 2PPh 2, 2; dpae, Ph 2AsCH 2CH 2AsPh 2, 3; dppe′, cis-Ph 2PCH=CHPPh 2, 4). Compounds 2–4 are the first examples of heterometallic complexes that contain two chiral primary phosphido bridges existing as pairs of diastereoisomers. [Pt(μ-PPhH) 2{Mo(CO) 5} 2(dppe)] ( 2) has been characterized spectroscopically and by a single-crystal X-ray analysis. The molecular structure of 2 can be considered either as Mo 2Pt phosphido-bridged trimer or a square-planar Pt II complex bonded to one chelating dppe and two anionic phosphine ligands. The latter PtP 4 description successfully accounts for the line broadening observed in the 31P{ 1H} NMR spectra of 2–4, which can be understood in terms of the existence of several interconverting rotameric forms arising from restricted rotation about the Pt-phosphido bond. The PtPMo angles of 122.1(1) and 123.5(1)° are some of the largest ever to be reported for phosphido-bridged heterometallics, reflecting the long PtMo separations [4.349(2) and 4.320(2) Å] and the electronic and structural flexibility of the phosphido bridge. The PtMo compound [Pt(μ-PPhH) 2{Mo-(CO) 4} (dppe)] (5), comprised of one neutral and one dianionic chelate ligand, was prepared from [Li] 2[Mo(CO) 5(PPhH) 2] and [PtCl 2(dppe)] and was shown to contain a conformationally rigid PtP 4 structure with characteristically sharp 31P resonances. The 31P{ 1H} NMR spectrum of 5 is rich with information analysing as two overlapping AA′XX′ spin systems together with their AA′XX′M (M = 195Pt) counterparts. The values of 2 J(P-P) and 1J( 195 Pt-P) are significantly lower for PPhH{Mo(CO) 5}− than dppe, a difference that cannot be accounted for solely on the basis of bond length variations. Meso-[Pt(μ-PPhH) 2{Mo(CO) 5} 2(dppe)] ( 2) is thermodynamically unstable, undergoing a rapid intramolecular elimination of [Mo(CO) 6] to generate [Pt(μ-PPhH) 2{Mo(CO) 4} (dppe)] (5), while its racemic diastereoisomer, that which was observed in the crystal, decomposes to unidentified phosphorus-containing products.

Synthetic, Structural, Spectroscopic, and Theoretical Studies of Structural Isomers of the Cluster Pt(3)(&mgr;-PPh(2))(3)Ph(PPh(3))(2). A Unique Example of Core Isomerism in Phosphine Phosphido-Rich Clusters.

Two isomers of the phosphido-bridged platinum cluster Pt(3)(&mgr;-PPh(2))(3)Ph(PPh(3))(2) (2 and 3) have been isolated, and their structures have been solved by single-crystal X-ray diffraction. Compound 2 crystallizes in the orthorhombic space group Cmc2(1) with a = 22.192(10) Å, b = 17.650(9) Å, c = 18.182(8) Å, and Z = 4. Compound 3 crystallizes with 2 molecules of dichloromethane in the monoclinic space group C2/c with a = 21.390(10) Å, b = 18.471(9) Å, c = 19.021(11) Å, beta = 105.27(5) degrees, and Z = 4. The two isomers differ essentially in their metal-metal distances and Pt-(&mgr;-PPh(2))-Pt angles. Thus 2, having an imposed C(s) symmetry, contains a bent chain of metal atoms with two short Pt-Pt distances of 2.758(3) Å and a long separation of 3.586(2) Å. In 3, which has an imposed C(2) symmetry, the metal atoms form an isosceles triangle with two Pt-Pt distances of 2.956(3) Å and one of 3.074(4) Å. These isomers can be smoothly interconverted by changing the crystallization solvents. Solution and solid-state (31)P NMR studies have been performed in order to assign the resonances of the different P nuclei and relate their chemical shifts with their structural environments. Raman spectroscopy was used to assign the nu(Pt-Pt) modes of the two structural isomers. Theoretical studies based on extended Hückel calculations and using the fragment molecular orbital approach show that the isomer with the three medium Pt-Pt distances is slightly more stable, in agreement with earlier theoretical predictions. Cluster core isomerism remains a rare phenomenon, and the present example emphasizes the role and the importance of flexible phosphido bridges in stabilizing clusters as well as the unprecedented features which can be observed in phosphine phosphido-rich metal clusters.

Reaction of the salt [Cp 2Nb(CO)PPhHCl] +, Cl − with HO −, MeO − and Fe(CO) 42−: New synthetic routes to metallophosphinites and functionalized phosphido-bridged heterobimetallic complexes

The anions HO − and MeO − performed deprotonation and nucleophilic substitution at the phosphorus centre in the salt [Cp 2Nb(CO)PPhHCl] +, Cl −, affording the neutral metallophosphanes Cp 2Nb(CO)PPhH(O) and Cp 2Nb(CO)PPh(OMe), respectively. When the Collman reagent Fe(CO) 4 2− was used, the same salt led to a mixture of mono-and dibridged heterobimetallic complexes Cp 2Nb(CO)(μ-PPhH)Fe(CO) 4 and Cp 2Nb(μ-PPhH, CO)Fe(CO) 3. Removal by photolysis of one carbonyl ligand from the monobridged compound produced the dibridged one. The treatment of binuclear complexes with KH and CH 3I achieved the substitution of the hydrogen atom at the phosphido bridge by a methyl group. All the new complexes have been characterized by 1H and 31P NMR and IR spectroscopies.

REACTIVITY OF [M3(μ-H)(CO)10(μ-PH2)] (M = Ru, Os) TOWARDS ORGANIC AND ORGANOMETALLIC ELECTROPHILES; EVIDENCE FOR ELECTROPHILICendo-ATTACK AT THE PHOSPHIDO MOIETY OF [Os3(μ-H)(CO)10(μ-PH2)

Abstract Electrophilic attack on the bridging phosphido moiety of [Os3(μ-H)(CO)10(μ-PH2)] (1) allows the formation of new phosphorus-containing compounds. The phosphido clusters [Os3(μ-H)(CO)10(μ-PHR)] (R = (CH2)6I (2a), (CH2 10I (2b) C4H8OH(2c), HOs3(CO)10(PPh3) (4a), HOs3(CO)10{P(OMe)3} (4b)) have been synthesized by the reaction of 1 with the appropriate electrophiles. When R = alkyl, both exo- and endo-isomers are formed. The formation of both isomers indicates that endo-attack plays a significant role in these reactions. When R = (μ-H)Os3(CO)10(PR3) the exo-isomers are the exclusive products. Reaction of the ruthenium analogue of 1 with [Os3(CO)10(NCMe)] leads to the formation of [Ru3Os3(μ-H)3(CO)20(μ4-P)] (6). The crystal structure of [Os6(μ-H)2(CO)20{P(OMe)3}(μ3-PH)] (4b) is presented.

Pentacarbonyl-1κC,2κ4C-bis[1,1(η5)-cyclopentadienyl](dimethylphenylphosphine-2κP)-μ-dimethylphosphanido-niobiumtungsten

The title complex, [NbW(C 2 H 6 P)(C 5 H 5 ) 2 (CO) 5 (C 8 H 11 P)], belongs to a small family of monophosphido-bridged transition metal complexes without both a metal-metal bond and any other bridges. The observed geometries of the Nb (distorted tetrahedral) and W (cis-octahedral) centers are as expected with a significantly enlarged Nb-P(1)-W angle of 124.9 (2)°. The methyl groups of the bridging phosphido ligand adopt an endo orientation towards the CO (Nb-CO) ligand which compels them to adopt symmetrical positions with respect to the (OC)NbP plane, bisecting that of the cyclopentadienyl rings. Consequently, the C(Nb-CO), Nb, P and W atoms are coplanar

Synthesis of dimanganese complexes containing mixed bridging phosphido ligands; crystal structures of [Mn 2(μ-PPh 2){μ-PPhMN(CO) 5}(CO) 8] and [MN 2(μ-PPhH) (μ-PPhCOMe) (CO) 8

The synthesis of a number of dimanganese complexes each containing two different bridging phosphido ligands is reported. The complex Mn 2(μ-PPh 2)(μ-PPhH)(CO) 8 ( 1) is prepared by the reaction of [Mn 2(CO) 10] firstly with PPh 2H followed by reaction with PPhH 2 in decalin. The reaction of 1 with CCl 4 gives Mn 2(μ-PPh 2)(μ-PPhCl)(CO) 8 ( 2) and deprotonation of 1 with n-BuLi followed by reaction of the deprotonated species with RX (X  halide) or [Mn(CO) 5 Br] gives the complexes [Mn 2(μ-PPh 2)(μ-PPhR)(CO) 8 (R  Me( 3a),Et( 3b , CH 2COMe( 3c) or CO 2Et( 3d) and [Mn(μ-PPh 2){μ-PPhMn(CO) 5}(CO 5(CO) 8] ( 4). The deprotonation of [Mn 2(μ-PPhH) 2(Co) 8] with one equivalent of n-BuLi and subsequent reaction with McCOCI gives [Mn 2(μ-PPhH)(μ-PPhCOMe)(CO) 8] ( 5) which exists in solution as a mixture of isomers. The structures of [Mn 2(μ-PPh 2){μ-PPhMn(CO) 5}(CO) 8] ( 4) and of trans-Mn 2(μ-PPhH)(μ-PPhCOMe)(CO) 8] ( 5) have been determined by single-crystal X-ray studies. All the complexes have been characterized spectroscopically and by elemental analysis.