Complexes du titane et du zirconium contenant les ligands cyclopentadienyldiphenylphosphine et cyclopentadienylethyldiphenylphosphine: acces a des structures heterobimetalliques

Reactions of Ph₂P(CH₂)_n(C₅H₄)Li, (n = 0, 2), with MCl₄ or CpTiCl₃ (M = Ti, Zr; Cp = η⁵-C₅H₅) form Cl₂M[(η⁵-C₅H₄)(CH₂)_nPPh₂]₂ or Cl₂CpTi[(η⁵-C₅H₄)-(CH₂)₂PPh₂] in good yields. Chemical reduction with Al, or electrochemical reduction of these complexes, under CO, are described. The titanium(IV) and zirconium(IV) derivatives react with metal carbonyls (Mo(CO)₆, Cr(CO)₆, Fe(CO)₅, Mo(CO)₄(C₈H₁₂)) under formation of new heterobimetallic complexes. Reduction with Al of Cl₂CpTi[(η⁵-C₅H₄)(CH₂)₂PPh₂]Mo(CO)₅ under CO results in a new heterobimetallic species containing low valent titanium. Both complexes Cl₂M[(η⁵-C₅H₄)(CH₂)₂PPh₂]₂ (M = Ti, Zr) react with [Rh(μ-Cl)(CO)(C₂H₄)]₂ to yield {RhCl(CO)(Cl₂M[(η⁵-C₅H₄)(CH₂)₂PPh₂]₂)}x, which is assumed to be a dimer, in which the titanium or the zirconium compounds act as bridging diphosphine ligands between the rhodium atoms.     

Bridging versus chelating diphosphine in clusters: Isomers of Os3(CO)10(diphosphine)

Isomers of Os₃(CO)₁₀(diphosphine) (diphosphine = Ph₂P(CH₂)_nPPh₂; n = 2 (dppe), n = 3 (dppp), and n = 4 (dppb)) have been prepared in which the diphosphine is chelating (1,1-isomer) or bridging (1,2-isomer), respectively, by displacing butadiene or acetonitrile from the complexes Os₃(CO)₁₀(cis- or trans-C₄H₆) or Os₃(CO)₁₀(MeCN)₂. Ph₂PCH₂PPh₂ (dppm) gives only the known bridging (1,2-isomer) whichever starting material is used. Structures have been established by infrared, ³¹P and ¹³C NMR methods.     

Spectroscopic investigations on the structure and fluxionality of the trihaptocycloheptatrienyl complexes [MX(CO)2(LL)(η3-C7H7)] (M  Mo,W; X  I,Cl; LL  bisphosphine or diamine) and synthesis of the tetracyanoethene adducts [WI(CO)2{Ph2P(CH2)nPPh2}{η3-C9H7(CN)4}] (n = 1 or 2)

Spectroscopic investigations, including ³¹P, ¹H and ¹³C NMR studies, on the formally 6-coordinate bisphosphine complexes [MX(CO)₂{Ph₂P(CH₂)_nPPh₂}(η³-C₇H₇)] (M  Mo, W; X  I, Cl; n = 2 (dppe), n = 1 (dppm); C₇H₇  cycloheptatrienyl) reveal a structure with no molecular plane of symmetry in which inequivalent P-donor atoms are arranged cis-cis and cis-trans to the two mutually cis-carbonyl groups. The dppe complexes exhibit a fluxional process which interconverts inequivalent phosphorus environments. Low temperature ¹H and ¹³C NMR studies on the diamine derivatives [MCl(CO)₂(H₂NCH₂CH₂NH₂)(η³-R)] (M  Mo, W, R  C₇H₇; M  Mo, R  C₃H₅ (allyl)) imply that the non-symmetric structure of the bisphosphine analogues is adopted. The adducts [WI(CO)₂{Ph₂P(CH₂)_n-PPh₂} {η³-C₉H₇(CN)₄}] (n = 1 or 2) are formed by tetracyanoethene addition to the trihapto-bonded cycloheptatrienyl ring of the tungsten complexes [WI(CO)₂-{Ph₂P(CH₂)_nPPh₂}(η³-C₇H₇)] (n = 1 or 2).     

Metallorganische lewissäuren: XXV. Übergangsmetallkomplexe mit o-koordiniertem perrhenat

The O-perrhenato complexes L_nMOReO₃ (L_nM = Re(CO)₅, Rh(PPh₃)₂(CO), Ir(PPh₃)₂(CO), Pt(PPh₃)₂(H), Ru(η⁵-C₅H₅)(PPh₃)₂, Os(PPh₃)₃(CO)(H), Ir(PPh₃)₂(CO)(H)(Cl) have been prepared from the corresponding halogeno compounds with AgReO₄ or NaReO₄, respectively. The spectroscopic data (IR, ¹H NMR) indicate that ReO₄⁻ is a stronger ligand compared to ClO₄⁻, SO₃CF₃⁻ and BF₄⁻.     

Activation of thiocyanogen and selenocyanogen by low oxidation state transition metal complexes

Thiocyanogen and selenocyanogen react with Ru(CO)₃(PPh₃)₂ to give respectively the complexes Ru(CO)₂(PPh₃)₂(NCS)₂ and Ru(CO)₂(PPh₃)₂(NCSe)₂. (M—NCS and M—SCN represent N- and S-thiocyanato groups, M—NCSe and M—SeCN represent N- and Se-selenocyanato groups respectively, while M—CNS indicates the bridging coordination mode of thiocyanate.) Only the thiocyanogen reacts with Ru₃(CO)₁₂ giving [Ru(CO)₂(CNS)₂]_n, which dissolves in hot coordinating solvents, such as pyridine, to form Ru(CO)₂(py)₂(NCS)₂. Selenocyanogen is less effective than thiocyanogen in the oxidative addition reactions with rhodium(I) and iridium(I) complexes; in fact selenocyanogen does not react with Rh(CO)(PPh₃)₂Cl while with Ir(CO)(PPh₃)₂Cl the former gives Ir(CO)(PPh₃)₂(SeCN)₂Cl by an equilibrium reaction. The coordination number of the metal and the charge on the complex do not change the bonding mode of the thiocyanate and selenocyanate groups in the iridium(III) complexes; in the Ir(PPh₃)₂ClX₂ and [Ir(Ph₂PC₂H₄PPh₂)₂X₂]⁺ (X = SCN and SeCN) complexes the pseudohalogens are S- and Se-bonded.The complexes trans-M(PPh₃)₂(SeCN)₂ (M = Pd, Pt) have been obtained by reacting M(PPh₃)₄ with selenocyanogen.     

Reactive Free Radicals : by J.M. Hay, Academic press, London, 1974, 158 pages, £4.40.

The linkage isomers CpM(CO)_nSCN and CpM(CO)_nNCS (Cp = η-C₅H₅; M = Fe, n = 2; M = Mo, n = 3) are interconverted by 366 nm irradiation in tetrahydrofuran solution at 30°C. Molybdenum and tungsten halide complexes CpM(CO)₂-(PPh₃)X undergo cistrans isomerization and disproportionation to CpM(CO)(PPh₃)₂X and CpM(CO)(PPh₃)₂X under similar conditions (benzene solution).     

Phosphin-stabilisierte carbonylnitrosylvanadium-verbindungen: Darstellung und spektroskopische eigenschaften

Numerous new complexes of the type V(CO)₅_n(NO)L_n, have been prepared either by nitrosylation of [V(CO)₆_nL_n]^?(n  2, 3) with NOX (X  Cl, BF₄) and [Co(NO)₂Br]₂, resp., or by reaction of L with “V(CO)₅NO” generated in situ. The compounds comprise n  1: L  PPh₃, PMe₂H, P(OMe)₃ and Ph₂PCH_2?PPh₂ (dppm); n  2: L₂2  2 PMe₂H, 2 PMe₃, 2 P(OMe)₃, dppm, Ph₂P(CH₂)_2?PPh₂, Ph₂P(CH₂)₃,PPh₂, Me₂P(CH₂)₂PMe₂, Ph₂As(CH₂)₂AsPh₂, o_?C₆H₄(AsMe₂)₂ (diars) and o_?C₆H₄(AsPh₂)PPh₂; n  3: L₃  1.5 diars and CH₃C(CH₂PPh₂)₃. IR (CO and NO stretching region) and ⁵¹V NMR spectra are discussed; for n  2 and 3, the positions of the arsine and phosphine ligands relative to NO are either cis for all the ligand functions (arsines) or cis/trans.     

Molybdenum and tungsten complexes with the heteroallyl-like Ph2P(O)C(S)NR− (R  Me,Ph) as ligand. X-ray structural analysis of Mo(CO)2(PPh3)(Ph2P(O)C(S)NPh)2 · CH2Cl2; A 4 : 3 piano-stool configuration

Ph₂P(O)C(S)N(H)R (R  Me, Ph) reacts with M(CO)₃(η⁵-C₅H₅)Cl (M  Mo, W) in the presence of Et₃N to give M(CO)₂(η⁵-C₅H₅)(Ph₂P(O)C(S)NR). The deprotonated ligand coordinates in a bidentate manner through N and S to give a four-membered ring system. M(CO)₃(PPh₃)₂Cl₂ (M  Mo, W) reacts with Ph₂P(O)C(S)N(H)R (R  Me, Ph) in the presence of Et₃N to give complexes in which the central metal atoms are seven coordinate through two ligands bonded via O and S to form five-membered ring systems, one PPh₃, and two CO groups. The complexes were characterised by elemental analyses, IR, ¹H NMR, and ³¹P NMR spectroscopy, and an X-ray structural analysis of Mo(CO)₂(PPh₃)(Ph₂P(O)C(S)NPh)₂ · CH₂Cl₂.     

Complexes containing phosphorus lignads—161: New phosphinite,phosphonite and phosphite derivatives of ruthenium,osmium and iridium

The complexes [MHCl(CO)(PPh₃)₃] (M = Ru or Os) readily undergo substitution at the site trans to the hydride ligand to afford phosphinite-, phosphonite-, or phosphite-containing products [MHCI(CO)(PPh₃)₂L] [L = P(OR)Ph₂, P(OR)₂Ph or P(OR)₃ respectively; R = Me or Et]. The ruthenium complexes alone undergo further substitution to afford complex cations [RuH(CO)(PPh₃)_nL_4?n]⁺ [n = 2, L = P(OMe)₃; n = 1, L = P(OR)₃; n = 0, L = P(OR)₂Ph or P(OR)Ph₂] which were isolated and characterised as their tetraphenylborate salts. Synthesis of the cationic complexes [IrHL₅][BPh₄]₂ [L = P(OR)₃, R = Me or Et] is also reported. Stereochemical assignments based on NMR data are given, and second order ³¹P and high field ¹H NMR patterns are analysed.     

Addition von kationischen Lewis‐Säuren [M′Ln]+ (M′Ln = Fe(CO)2Cp,Fe(CO)(PPh3)Cp,Ru(PPh3)2Cp,Re(CO)5, ${1 \over 2}$ Pt(PPh3)2, W(CO)3Cp an die anionischen Thiocarbonyl‐Komplexe [HB(pz)3(OC)2M(CS)]− (M = Mo,W; pz = 3,5‐dimethylpyrazol‐1‐yl)

Addition of Cationic Lewis Acids [M′L_n]⁺ (M′L_n = Fe(CO)₂Cp, Fe(CO)(PPh₃)Cp, Ru(PPh₃)₂Cp, Re(CO)₅, Pt(PPh₃)₂, W(CO)₃Cp to the Anionic Thiocarbonyl Complexes [HB(pz)₃(OC)₂M(CS)]⁻ (M = Mo, W; pz = 3,5‐dimethylpyrazol‐1‐yl) Adducts from Organometallic Lewis Acids [Fe(CO)₂Cp]⁺, [Fe(CO)(PPh₃)Cp]⁺, [Ru(PPh₃)₂Cp]⁺, [Re(CO)₅]⁺, [ Pt(PPh₃)₂]⁺, [W(CO)₃Cp]⁺ and the anionic thiocarbonyl complexes [HB(pz)₃(OC)₂M(CS)]⁻ (M = Mo, W) have been prepared. Their spectroscopic data indicate that the addition of the cations occurs at the sulphur atom to give end‐to‐end thiocarbonyl bridged complexes [HB(pz)₃(OC)₂MCSM′L_n].     

Ditertiary phosphine complexes of (ν-allyl)dicarbonylmolybdenum(II) and -tungsten(II)

Compounds of the type [XM(CO)₂(ν-allyl)L₂] (where X = Cl and Br; M = Mo and W; L₂ = Ph₂PCH₂PPh₂ and Ph₂ PCH₂CH₂PPh₂) have been prepard from the corersponding MeCN complexes. The spectral properties of these compounds and the effects of chelate rign size on ³¹P coordination shifts and J(¹⁸³W—³¹P) have been investigated.     

Potential inhibitors of DNA topoisomerase II: ruthenium(II) poly-pyridyl and pyridyl-azine complexes

In search of new DNA probes a series of new mono and binuclear cationic complexes [RuH(CO)(PPh₃)₂(L)]⁺ and [RuH(CO)(PPh₃)₂(-μ-L)RuH(CO)(PPh₃)₂]²⁺ [L=pyridine-2-carbaldehyde azine (paa), p-phenylene-bis(picoline)aldimine (pbp) and p-biphenylene-bis(picoline)aldimine (bbp)] have been synthesized. The reaction products were characterized by microanalyses, spectral (IR, UV-Vis, NMR and ESMS and FAB-MS) and electrochemical studies. Structure of the representative mononuclear complex [RuH(CO)(PPh₃)₂(paa)]BF₄ was crystallographically determined. The crystal packing in the complex [RuH(CO)(PPh₃)₂(paa)]BF₄ is stabilized by intermolecular π-π stacking resulting into a spiral network. Topoisomerase II inhibitory activity of the complexes and a few other related complexes [RuH(CO)(PPh₃)₂(L)]⁺ {L=2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz) and 2,3-bis(2-pyridyl)-pyrazine (bppz)} have been examined against filarial parasite Setaria cervi. Absorption titration experiments provided good support for DNA interaction and binding constants have also been calculated which were found in the range 1.2 × 10³-4.01 × 10⁴ M⁻¹.     

Stepwise reduction of the thiocarbonyl ligand: hydride transfer to CS: thioformyl,thioformaldehyde, methylthiolato,secondary carbene,formyl and iminoformyl complexes of osmium

The complexes OsHX(CS)L(PPh₃)₂ (X  Cl, Br; L  CO and X  Cl; L  CN-p-tolyl), which contain mutually cis hydrido and thiocarbonyl ligands, undergo transfer of the hydrido ligand to CS when treated with CO to give blue complexes containing the thioformyl ligand [OsCHS]. OsCl(CHS)(CO)₂(PPh₃)₂ reacts with borohydride to give the first metal complex of the thioformaldehyde monomer, viz. Os(η²-CH₂S)(CO)₂(PPh₃)₂, which reacts rapidly with HCl to give OsCl(SCH₃)(CO)₂(PPh₃)₂ and then, by a slower reaction, OsCl₂(CO)₂(PPh₃)₂ and CH₃SH. The ligands produced in this stepwise reduction have possible relevance as models for postulated intermediates in the Fischer—Tropsch synthesis. Synthetic routes to formyl [OsCHO], iminoformyl [OsCHNMe] and secondary carbene complexes [OsCHSMe, OsCHNMe₂, OsCHOMe] are also demonstrated.     

Metallkomplexe mit biologisch wichtigen Liganden. LXXXII. Triphenylphosphan-Molybdän-, Wolfram-, Ruthenium- und Iridium-Komplexe mit N-acylierten α-Aminocarboxylaten

Metal Complexes of Biological Important Ligands. LXXXII. Triphenylphosphine Molybdenum, Tungsten, Ruthenium, and Iridium Complexes of N-Acyl-α-Aminocarboxylates The reactions of the hydrido complexes RuHCl(CO) · (PPh₃)₃, RuH₂(PPh₃)₄ and IrH₃(PPh₃)₃ with N-acyl-α-aminocarboxylates give the carboxylate complexes RuCl(O₂CCHRNHCOR′)(CO)(PPh₃)₂ ( 1–3 ), RuH(O₂CCHRNHCOR′)(PPh₃)₃ ( 4–6 ) and IrH₂(O₂CCH₂NHCOPh)(PPh₃)₃ ( 7 ). The structure of RuCl · (O₂CCHNHCOPh)(CO)(PPh₃)₂ ( 1 ) has been determined by x-ray diffraction. The triphenylphosphine complexes MBr · (O₂CCH₂NHCOR)(CO)₂(PPh₃)₂ (M = Mo, W) ( 8–12 ) and Mo(O₂CCHRNHCOR′)₂(CO)₂(PPh₃)₂ ( 13–17 ) are formed from MBr₂(CO)₂(PPh₃)₂ (M = Mo, W) with one or two equivalents of N-acyl-a-aminoacidates, respectively.     

Carbonylcobalt(I) complexes. The crystal and molecular structure of [Co(CO)(dppm)2]ClO4

New anionic carbonylcobalt(I) complexes [X₂Co(CO)₂(PPh₃)](PR₄) (X=Cl, PR₄ = PBzPh₃ (I); X = Br, PR₄ = PEtPh₃ (II)) have been prepared by reduction of the cobalt(II) halides with NaBH₄ in the presence of PPh₃ and the phosphonium salt PR₄X. Cleavage of halide bridges in dimeric or polymeric [XCo(PPh₃)₂]_n and [XCo(PPh₃)]_n gives the neutral dicarbonyl derivatives XCo(CO)₂PPh₃)₂. Treatment of ClCo(CO)₂(PPh₃)₂ with alkylating agents gives the known σ- and η- organocobalt(I) derivatives, and reactions with TIClO₄ in the presence of various amounts of different mono- and bi-dentate phosphines give the cationic tricarbonyl [Co(CO)₃(PPh₃)₂]⁺, dicarbonyl [Co(CO)₂(PMePh₂)₃]⁺ and monocarbonyl [Co(CO)L₄]⁺ complexes (L₄ = 4P(OMe)₃, 2 dppe and 2dppm). The dppm complex crystallizes in the monoclinic space group P2₁/c with a 17.895(6), b 10.751(2), c 24.687(4) Å, β 98.92(1)°, and D_calc 1.35 g cm⁻³ for Z = 4. A final R value of 0.077 ( R_w = 0.061), based on 2656 observed reflections, was obtained. The cobalt atom exhibits a distorted trigonal bipyramidal geometry. The perchlorate anion is severely disordered or freely rotating.     

About the Reaction of C(PPh3)2 with [M(CO)6] (M = Cr,Mo): Unusual Formation of μ-Carbonato Complexes of Mo under Participation of THF

Attempts to synthesize complexes of group 6 carbonyl compounds [M(CO)₆] (M = Cr, Mo, W) with the carbone C(PPh₃)₂ ( 1 ) via the photo chemically created adducts [(CO)₅M(THF)] lead to quantitative formation of the salts [HC(PPh₃)₂]₂[M₂(CO)₁₀] ( 2 , Cr; 3 , Mo; 4 , W). Alternatively, a long-time thermal reaction of [Mo(CO)₆] performed with 1 in THF generates a series of products initiated by a Wittig-type reaction. In addition to 3 , minor amounts of [(CO)₅MoCCPPh₃] ( 8 ), [(CO)₅MoO₂CC{PPh₃}₂] ( 5 ), and the carbonate complexes [HC(PPh₃)₂]₂[(CO)₅Mo(CO₃)Mo(CO)₄] ( 6 ) and [HC(PPh₃)₂]₂[(CO)₄Mo(CO₃)Mo(CO)₄] ( 7 ) were found. Compounds 2 , 3 , 5 , 6 , and 7 were characterized by X-ray analyses, ³¹P NMR, and IR spectroscopy. The water, necessary for the formation of the carbonate, stems from decomposition of THF.     

Chemie der carbonylniobverbindungen: X. Neue hydridocarbonylkomplexe des vanadiums,niobs und tantals

Complexes of the general formula HM(CO)_n(oligophos) (M = V, n = 2; M = Nb, n = 3 and 2; M = Ta, n = 3) have been prepared by ion exchange on silica gel from their ionic precursors [Et₄N][M(CO)_4,3(oligophos)] (n = 3) or by UV irradiation of HM(CO)_n+1(oligophos) (n = 2). The new compounds, including fac-[Et₄N]-[Nb(CO)₃PPh(CH₂CH₂PPh₂)₂] and cis-[Et₄N][Ta(CO)₄PPh(CH₂CH₂PPh₂)₂], are characterized by their IR (ν(CO)), ¹H (hydride), ³¹P and metal (⁵¹V and ⁹³Nb) NMR spectra.     

New Heteronuclear Bridged Borylene Complexes That Were Derived from [{Cp*CoCl}2] and Mono‐Metal?Carbonyl Fragments

The synthesis, structural characterization, and reactivity of new bridged borylene complexes are reported. The reaction of [{Cp*CoCl}₂] with LiBH₄ ? THF at ?70 °C, followed by treatment with [M(CO)₃(MeCN)₃] (M=W, Mo, and Cr) under mild conditions, yielded heteronuclear triply bridged borylene complexes, [(μ₃‐BH)(Cp*Co)₂(μ‐CO)M(CO)₅] ( 1 – 3 ; 1 : M=W, 2 : M=Mo, 3 : M=Cr). During the syntheses of complexes 1 – 3 , capped‐octahedral cluster [(Cp*Co)₂(μ‐H)(BH)₄{Co(CO)₂}] ( 4 ) was also isolated in good yield. Complexes 1 – 3 are isoelectronic and isostructural to [(μ₃‐BH)(Cp*RuCO)₂(μ‐CO){Fe(CO)₃}] ( 5 ) and [(μ₃‐BH)(Cp*RuCO)₂(μ‐H)(μ‐CO){Mn(CO)₃}] ( 6 ), with a trigonal‐pyramidal geometry in which the μ₃‐BH ligand occupies the apical vertex. To test the reactivity of these borylene complexes towards bis‐phosphine ligands, the room‐temperature photolysis of complexes 1 – 3 , 5 , 6 , and [{(μ₃‐BH)(Cp*Ru)Fe(CO)₃}₂(μ‐CO)] ( 7 ) was carried out. Most of these complexes led to decomposition, although photolysis of complex 7 with [Ph₂P(CH₂)_nPPh₂] (n=1–3) yielded complexes 9 – 11 , [3,4‐(Ph₂P(CH₂)_nPPh₂)‐closo‐1,2,3,4‐Ru₂Fe₂(BH)₂] ( 9 : n=1, 10 : n=2, 11 : n=3). Quantum‐chemical calculations by using DFT methods were carried out on compounds 1 – 3 and 9 – 11 and showed reasonable agreement with the experimentally obtained structural parameters, that is, large HOMO–LUMO gaps, in accordance with the high stabilities of these complexes, and NMR chemical shifts that accurately reflected the experimentally observed resonances. All of the new compounds were characterized in solution by using mass spectrometry, IR spectroscopy, and ¹H, ¹³C, and ¹¹B NMR spectroscopy and their structural types were unequivocally established by crystallographic analysis of complexes 1 , 2 , 4 , 9 , and 10 .     

The synthesis of thionitrosodimethylamine (Me2NNS) complexes of ruthenium,osmium, and iridium

Neutral hydrido complexes [ML]ClH(PPh₃)₃ ([ML] = Ru(CO), Os(CO) and Ir(Cl)] react with thionitrosodimethylamine, Me₂NNS, to give [ML]ClH-(SNNMe₂)(PPh₃)₂ with H trans to Me₂NNS, while the hydrido cations cis,trans-[[ML]H(SNNMe₂)₂(PPh₃)₂]⁺ are obtained from Me₂NNS and [Ru(NCMe)₂(CO)-(PPh₃)₂]⁺, [OsH(OH₂)(CO)(PPh₃)₃]⁺ and [IrClH(NCMe)₂(PPh₃)₂]⁺, respectively. The coordinatively unsaturated aryl complexes [ML′]Cl(p-tolyl)(PPh₃)₂ ([ML′]Ru(CO), Os(CO) and Os(CS)) coordinate one molecule of Me₂NNS to give [ML′]Cl(p-tolyl)(SNNMe₂)(PPh₃)₂, the chloride ligands of which are labile. Spectroscopic data suggest that in all these complexes the Me₂NNS ligand adopts a η¹(S) coordination mode.     

Reaction studies on some functionalized alkyl transition metal compounds and the crystal structure of [Cp(CO)3W{(CH2)3NO2}]

The reactions of the halogenoalkyl compounds [Cp(CO)₃W{(CH₂)_nX}] (Cp = η⁵-C₅H₅; n = 3-5; X = Br, I) and [Cp(CO)₂(PPhMe₂)Mo{(CH₂)₃Br}] with the nucleophiles Z = CN⁻ and gave compounds of the type [Cp(CO)₃W{(CH₂)_nZ}] for the tungsten compounds, whilst cyclic carbene compounds were obtained from the reactions of the molybdenum compound. The reactions of [Cp(CO)₃W{(CH₂)_nBr}] (n = 3, 4) and [Cp(CO)₂(PPhMe₂)Mo{(CH₂)₃Br}] with gave [Cp(CO)₃W{(CH₂)_nONO₂}] and [Cp(CO)₂(PPhMe₂)Mo{(CH₂)₃ONO₂}], respectively. The reaction of [Cp(CO)₃W{(CH₂)_nBr}] with AgNO₂ gave [Cp(CO)₃W{(CH₂)_nNO₂}]. In the solid state the complex [Cp(CO)₃W{(CH₂)₃NO₂}] crystallizes in a distorted square pyramidal geometry. In this molecule the nitropropyl chain deviates from the ideal, all-trans geometry as a result of short, non-hydrogen intermolecular N-O?O-N contacts. The reactions of the heterobimetallic compounds [Cp(CO)₃W{(CH₂)₃}ML_y] {ML_y = Mo(CO)₃Cp, Mo(CO)₃Cp^∗ and Mo(CO)₂(PMe₃)Cp; Cp^∗ = η⁵-C₅(CH₃)₅} with PPh₃ and CO were found to be totally metalloselective, with the ligand always attacking the metal site predicted by the reactions of the corresponding monometallic analogues above with nucleophiles. Thus the compounds [Cp(CO)₃W{(CH₂)₃}C(O)ML_z] {ML_z = Mo(CO)₂YCp, Mo(CO)₂YCp^∗ and Mo(CO)Y(PMe₃)Cp; Y = PPh₃ or CO} were obtained. Similarly, the reaction of [Cp(CO)₂Fe{(CH₂)₃}Mo(CO)₂(PMe₃)Cp] with CO gave only [Cp(CO)₂Fe{(CH₂)₃C(O)}Mo(CO)₂(PMe₃)Cp]. Hydrolysis of the bimetallic compound, [Cp(CO)₃W(CH₂)₃C(O)Mo(CO)(PPh₃)(PMe₃)Cp], gave the carboxypropyl compound [Cp(CO)₃W{(CH₂)₃COOH}]. Thermolysis of the compound [Cp(CO)₂Fe(CH₂)₃Mo(CO)₃(PMe₃)Cp] gave cyclopropane and propene, indicating that β-elimination and reductive processes had taken place.