Ligand Redistribution Process Research Articles

Combining two relatively weak bases (Zn(TMP)2 and KOtBu) for the regioselective metalation of non-activated arenes and heteroarenes.

Co-operation between two relatively weak Brønsted bases, Zn(TMP)2 and KOtBu, produces a bimetallic base strong enough to regioselectively zincate non-activated arenes such as naphthalene, biphenylene and anthracene under mild conditions. This co-operativity is also effective with a range of more sensitive five-membered ring heterocyclic substrates including benzoxazole and caffeine. Metalation products have been intercepted with iodine, affording the relevant iodo-(hetero)arenes in good to excellent yields with finely tuned regioselective control. Combining NMR spectroscopic and X-ray crystallographic studies has uncovered that depending on the solvent, a complicated ligand distribution process of mixed aryl/alkoxy higher order zincate intermediates, (THF) n K2Zn(Ar)2(OtBu)2, that can liberate lower order zincates of the form [(THF)2KZn(Ar)(OtBu)2]2 and eliminate potassium aryl species. While this ligand redistribution process seems to operate for non-substituted (hetero)arene metalation products, for non-activated alkylarenes such as mesitylene or m-xylene the higher-order zincates resulting from their lateral metalation are stable in solution and the solid state, which is attributed to the greater π-stabilisation that these systems can provide to the K cations. Adding another layer of complexity to this heterobimetallic system, over time the Zn(TMP)2/2KOtBu combination reacts with the THF solvent of these reactions, to afford an unusual decomposition product which contains an s-trans-1,3-butadienyl (C4H5 -) fragment coordinated to Zn within a potassium zincate structure. The formation of the latter is attributed to the initial synergistic α-zincation of THF, followed by subsequent ring opening and oxygen extrusion.

Interaction and Energy Decomposition Analyses to Predict Stability of Tetraaryl Square Planar Cobalt Complexes

AbstractThe sodium‐mediated cobaltation of pentafluorobenzene using the bimetallic base [NaCo(HMDS)3] (HMDS=N(SiMe3)2) has been reported to afford a novel tetraaryl Co(II) square planar complex. Yet, the preparation of analogue structures with 1,2,3,4‐tetrafluorobenzene, 1,3,5‐trichlorobenzene, and 1,4‐dibromo‐2,5‐difluorobenzene remains elusive. While the metalation step proceeds leading to stable [NaCo(HMDS)2Ar] species, the ligand redistribution process to afford the tetraaryl Co(II) square planar complexes does not take place. Herein we report a density functional theory study in combination with electronic structure and energy decomposition analyses to shed light on the electronic and steric requirements to afford such complexes. Our findings show that the formation of the Co(II) square planar complexes depends on the right balance between intramolecular X⋅⋅⋅X and Na⋅⋅⋅X (X=H, F, Cl, Br) interactions. The latter further induces a ‘seesaw effect’, whereby the aryl ligand acts as a ‘seesaw’ allowing two X atoms in ortho positions to interdependently interact with Na. Only by considering both attractive and repulsive Na(X)⋅⋅⋅X interactions, the correct stability of the square planar complexes observed in experiments can be predicted computationally. We envision these insights to guide the rational design of novel square planar metal complexes for C−C coupling, a field that is still dominated by scarce and expensive precious metals.

Rare-Earth Metal Boroxide with Formal Triple Metal–Oxygen Orbital Interaction: Synthesis from B(C 6 F 5 ) 3 ·H 2 O and Radical-Anion Ligated Rare-Earth Metal Amides

Rare-earth metal boroxides are not only rare and of great synthetic challenge but also important theoretically due to their unrevealed bonding characteristics. In this paper, we report the synthesi...

Uranium(iii) complexes supported by hydrobis(mercaptoimidazolyl)borates: synthesis and oxidation chemistry.

The reaction of [UI3(thf)4] with the sodium or lithium salts of hydrobis(2-mercapto-1-methylimidazolyl)borate ligands ([H(R)B(timMe)2]-) in a 1 : 2 ratio, in tetrahydrofuran, gave the U(iii) complexes [UI{κ3-H,S,S'-H(R)B(timMe)2}2(thf)2] (R = H (1), Ph (2)) in good yields. Crystals of [UI{κ3-H,S,S'-H(Ph)B(timMe)2}2(thf)2] (2) were obtained by recrystallization from a tetrahydrofuran/acetonitrile solution, and the ion-separated uranium complex [U{κ3-H,S,S'-H(Ph)B(timMe)2}2(CH3CN)3][I] (3-I) was obtained by dissolution of 2 in acetonitrile followed by recrystallization. One-electron oxidation of 2 with AgBPh4 or I2 resulted in the formation of the cationic U(iv) complexes [U{κ3-H,S,S'-H(Ph)B(timMe)2}3][X] (X = BPh4 (6-BPh4), I (6-I)), due to a ligand redistribution process. These complexes are the first examples of homoleptic poly(azolyl)borate U(iv) complexes. Treatment of complex 2 with azobenzene led to the isolation of crystals of the U(iv) compound [UI{κ3-H(Ph)B(timMe)2}2(κ2-timMe)] (7). Treatment of 2 with pyridine-N oxide (pyNO) led to the formation of the uranyl complex [UO2{κ2-S,S'-H(Ph)B(timMe)2}2] (8) and of complex 6-I, while from the reaction of [U{κ3-H(Ph)B(timMe)2}2(thf)3][BPh4] (5) with pyNO, the oxo-bridged U(iv) complex [{U{κ3-H(Ph)B(timMe)2}2(pyNO)}2(μ-O)][BPh4]2 (9) was also obtained. In the U(iii) and U(iv) complexes, the bis(azolyl)borate ligands bind to the uranium center in a κ3-H,S,S' coordination mode, while in the U(vi) complex the ligands bind to the metal in a κ2-S,S' mode. The presence of UH-B interactions in the solid-state, for the nine-coordinate complexes 1, 2, 3, 6 and 7 and for the eight-coordinate complex 9, was supported by IR spectroscopy and/or X-ray diffraction analysis.

Gold and Palladium Hetero-Bis-NHC Complexes: Characterizations, Correlations, and Ligand Redistributions

A series of new Au(I) hetero-bis-NHC complexes [Au(iPr2-bimy)(NHC)]X (X = BF4, PF6, 2–6) and the hetero-tetrakis-NHC complex [Au2(iPr2-bimy)2(μ-ditz)](BF4)2 (7) have been synthesized using the Au(I) acetato complex [Au(O2CCH3)(iPr2-bimy)] (C) as a basic metal precursor (iPr2-bimy = 1,3-diisopropylbenzimidazolin-2-ylidene, ditz = 1,2,4-triazolidine-3,5-diylidene). The Au(III) hetero-bis-NHC complex trans-[AuCl2(iPr2-bimy)(Bn2-bimy)]BF4 (12; Bn2-bimy = 1,3-dibenzylbenzimidazolin-2-ylidene) and the hetero-tetrakis-NHC complex all-trans-[Au2Cl4(iPr2-bimy)2(μ-ditz)](BF4)2 (13) were obtained by oxidation of their corresponding Au(I) hetero-NHC precursors. For all Au(I) hetero-NHC complexes, the 13C carbene signals of the constant iPr2-bimy ligand are found to be highly correlated with those in Pd(II) analogues of the type trans-[PdBr2(iPr2-bimy)(NHC)], which could be applied to detect the σ-donating ability of the trans-standing NHC. In addition, an interesting ligand redistribution process was observed for some of the Au(I) hetero-bis-NHC complexes.

Intermolecular Insertion of Dialkynylphosphanes into the M–C Bond of Cyclopalladated Rings through Activation by Cyclometallated Amines

AbstractA series of chiral ortho‐platinated and ‐palladated complexes derived from N,N,α‐trimethylbenzylamine has been prepared. The dialkynylphosphane PhP(C≡CMe)2 coordinated regiospecifically as a P→M monodentate ligand to these cyclometallated units in the positions trans to the nitrogen donors of the metallacycles. Upon introduction of selected chirality on the benzylamine unit and subsequent monitoring by using NMR spectroscopy, the P→Pt bond was found to be thermodynamically stable and kinetically inert. The P→Pd bond must be kinetically labile since the palladium complexes readily undergo a facile ligand redistribution process. Nevertheless, both ortho‐metallated units activated one of the C≡C bonds towards an intermolecular Pd–C bond insertion reaction into another cyclopalladated ring. No intramolecular insertion reaction occurred within the same molecule. Coordination of PhP(C≡CMe)2 to the ortho‐palladated unit also protected the organopalladium ring from intermolecular attack by other coordinated dialkynylphosphanes. The Pt–C bonds in cycloplatinated rings are not reactive toward the insertion reaction, although they are good reaction activators for coordinated dialkynylphosphanes.

Four-coordinate erbium organometallic and coordination complexes: Synthesis and structure

The synthesis and reactivity of several erbium organometallic and coordination complexes supported by a β-diketiminato ancillary ligand are described. The reaction of ErCl 3(THF) 3.5 with Li L ( L = ArNC(Me)CHC(Me)NAr; Ar = 2,6- i Pr 2-C 6H 3) afforded the dimeric complex Er( L)Cl(μ-Cl) 3Er( L)(THF), 1. Reaction of complex 1 with four equiv of the bulky silylamide LiN(SiMe 3) 2 generated the unexpected four-coordinate adduct dimer [Er( L)N(SiMe 3) 2Cl(μ-(LiN(SiMe 3) 2))] 2, 2. Conversely, reaction of 1 with two or four equiv of LiCH 2SiMe 3 led to the base-free mixed chloro/alkyl species [Er( L)(CH 2SiMe 3)(μ-Cl)] 2, 3, and the four-coordinate dialkyl Er( L)(CH 2SiMe 3) 2, 4, respectively. The protonolysis reactivity of 4 was demonstrated by reaction with [Et 3NH]I to generate Er( L)I 2, 5. By contrast, reaction of complex 1 with trimethylsilyliodide resulted in the formation of ErI 3(THF) 3, 6, through a ligand redistribution process. Compounds 1– 6 were characterized by single crystal X-ray diffraction, multinuclear NMR spectroscopy, FT-IR spectroscopy, solution magnetic susceptibility measurements and CHN combustion analysis.

Well-Defined Alkyl Heteroscorpionate Magnesium Complexes as Excellent Initiators for the ROP of Cyclic Esters

The reaction of the heteroscorpionate lithium salts [Li(tbpamd)(THF)] [tbpamd = N-ethyl-N‘-tert-butylbis(3,5-dimethylpyrazol-1-yl)acetamidinate] and [Li(pbpamd)(THF)] [pbpamd = N,N‘-diisopropylbis(3,5-dimethylpyrazol-1-yl)acetamidinate] with 1 equiv of RMgCl proceeds to give very high yields of the neutral heteroscorpionate alkyl magnesium complexes [Mg(R)(NNN)] (NNN = tbpamd, R = C3H5 1, tBu 2, CH2SiMe3 3; NNN = pbpamd, R = C3H5 4, tBu 5, CH2SiMe3 6). On heating toluene solutions of complexes 1−3, 5, and 6, a ligand redistribution process occurs to give the corresponding 6-coordinated sandwich complexes [Mg(tbpamd)2] (7) and [Mg(pbpamd)2] (8). Interestingly, the allyl derivative 4 can be easily transformed to 8 at room temperature. In addition, the cationic sandwich complex [Mg(tbpamdH)2]Cl2 (9) [tbpamdH = N-ethyl-N‘-tert-butylbis(3,5-dimethylpyrazol-1-yl)acetamidine] was obtained from 7 by means of a protonation process. Finally, alkyl-containing complexes 1−6 can act as highly effective single-componen...

Synthesis and structural characterization of gallium and indium complexes obtained from redistribution reactions of mixed chalcogen-imidodiphosphinate ligands

The ionic complex [Ga{N(SP i Pr 2)(SeP i Pr 2)- S, Se} 2] +[GaCl 4] − ( 5) was prepared by a ligand redistribution process from the mono-chelate [Cl 2Ga{N(SP i Pr 2)(SeP i Pr 2)- S, Se}] ( 3) complex in benzene. A similar phenomenon was observed for the heavier indium homologues, where the neutral complexes [ClIn{N(SP i Pr 2)(SeP i Pr 2)- S, Se} 2] ( 7) and [ClIn{N(OP i Pr 2)(SP i Pr 2)- O, S} 2] ( 8) were isolated along with InCl 3 as the main reaction by-product. Complexes 5, 7 and 8 were characterized by single-crystal X-ray structural analysis.

β-Diketiminato Scandium Chemistry: Synthesis, Characterization, and Thermal Behavior of Primary Amido Alkyl Derivatives

Treatment of the β-diketiminato-supported scandium dichlorides {[ArNC(R)CHC(R)NAr]ScCl2}n (Ar = 2,6-iPr2-C6H3; R = CH3, 1a, n = 2; R = tBu, 1b, n = 1) with 1 equiv of a lithium amide reagent LiN(H)R‘ (R‘ = tBu, 2,6-iPr2-C6H3) gave scandium amido derivatives. For 1a, use of LiN(H)tBu leads to the bis-amido derivative (6a) regardless of the equivalency of amide reagent employed, suggesting that facile ligand redistribution processes are operative when the ligand is the less bulky methyl-substituted example. For 1b, mono-amido chlorides 2b (R‘ = tBu) and 3b (R‘ = 2,6-iPr2-C6H3) are obtained in good yields, and these compounds can be alkylated with MeLi to provide mono-amido methyl compounds 4b (R‘ = tBu) and 5b (R‘ = 2,6-iPr2-C6H3). All four of these compounds were characterized crystallographically. The amido ligand occupies the exo coordination site exclusively, and there is no evidence in solution for a diastereomer with the amido group in the endo site. DFT calculations suggest that there is a strong steric preference and a slight electronic bias for the amido ligand to assume the exo position. Thermolysis of the amido methyl complex 4b leads to loss of CH4 and production of a scandacylic product, 7, formed via metalation with one of the N-aryl isopropyl methyl groups. This compound was characterized crystallographically. Deuterium labeling experiments suggest that 7 is produced via direct metalation and does not form via a scandium imido intermediate.

Synthesis and Structure of the Novel “Paddle-Wheel” Complex [{(η5-Cp)2Pb(μ:η5-Cp)K}·2THF

The reaction between CpPbCl and CpthfK(THF) (1:2 equiv, Cpthf = 2-tetrahydrofurfurylcyclopentadienyl) in THF solvent unexpectedly results in formation of the homoleptic paddle-wheel complex [{(η5-Cp)2Pb(μ:η5-Cp)K}·2THF] (3). The outcome of the reaction is likely to be due to a solvent-promoted ligand redistribution process.

Hydridoborates and hydridoborato metallates: Part 26. Preparation and structures of dihydridoborates of lithium and potassium

A series of alkali metal dihydrido borates has been prepared by three different routes. They were characterized by 11B-NMR spectroscopy and, in part, by IR spectroscopy. The following compounds were obtained: lithium dihydrido dimethyl borate and lithium methyl trihydrido borate, 1 and 2, lithium and potassium dihydrido di- tert-butyl borate, 3 and 4, lithium dihydrido dicyclopentyl borate, 5, lithium and potassium dihydrido 9-borata-bicyclo[3.3.0] nonane, 6a, b, potassium dihydrido boratacyclohexane, 7, lithium dihydrido boratacycloheptane, 8, and lithium dihydrido-9-boratafluorene, 9. In the process of the formation of 1 and 7 also Li(H 3BMe) 2 and Li 2(H 3B(CH 2) 5BH 3) are formed, most likely by a ligand redistribution process which is not operative if bulky organyl groups are bound to the boron atom or if the boron atom is part of a ring system. In case of catecholate no H 2B(OR) 2 − anions were detected but for ephedrino or dithiolato ligands the corresponding dihydrido borate complexes were readily detected by 11B-NMR but the latter converted in THF solution into B(S 2R’) 2 anions. MO calculations show that the ligand redistribution for H 2BX 2 − ions into BH 4 − and BX 4 − becomes thermodynamically more favored with increasing electronegativity of the substituent X. Characterization of the new hydrido borate species is usually unambiguous, but 10 shows an anomalous temperature dependent behavior in THF solution which can be attributed to an equilibrium involving Li(2H, 2O), Li(2H, 3O), and Li(3O) structural units. This is supported by the X-ray structure of dimeric 10·THF and monomeric 10·THF·TMEDA. While 9·3THF is monomeric and contains doubly bridging H 2B groups all other dihydrido diorganyl borates are dinuclear. The interaction between the alkali metal center and the boron bonded H atoms depends on number and size of the auxiliary ligands. ‘Agostic’ Li⋯HC interactions play a role if β-H atoms are present and when the alkali metal cation is not coordinatively saturated by the auxiliary ligand and the H(B) hydrogens. The most symmetric and so far unique arrangement is found for [ 6a·2THF] 2 where all four H(B) hydrogens form Li⋯H⋯Li bridges. Also lithium bis(dithiocatecholato)borate, 17·2 THF is dimeric. Its Li centers are coordinated by four sulfur and two oxygen atoms. These atoms form a double heterocubane structure with two diametral edges missing.

Dialkyl(butadiene)cyclopentadienylmolybdenum(III) Complexes. Synthesis, Characterization, and Reactivity

Treatment of CpMo(η4-diene)Cl2 (diene = 1,3-butadiene, C4H6, 1‘; isoprene, C5H8, 1‘ ‘; 2,3-dimethyl-1,3-butadiene, C6H10, 1‘ ‘) in diethyl ether at low temperature with 2 equiv of alkylmagnesium RMgX reagents affords the corresponding dialkyl complexes CpMo(η4-1,3-diene)R2 (2, 2‘, 2‘ ‘, R = CH3, a; CH2Ph, b; CH2SiMe3, c). These species are isolable in moderate yields and have been fully characterized by EPR, elemental analyses, and cyclic voltammetry. They all show a reversible reduction process at relatively low potentials and an irreversible oxidation. The structure of 2‘ ‘a was confirmed by single-crystal X-ray diffraction. The mixed complex CpMo(η4-C4H6)Cl(CH3), 3, has also been obtained by selective monomethylation of 1. A slow ligand redistribution process occurs between equivalent amounts of 1 and 2a to afford 3 quantitatively. Compound 3 slowly decomposes by elimination of a CH3 group, yielding compound [CpMo(η4-C4H6)Cl]2, 4, which has been structurally characterized by X-ray crystallography. Aryl...

Iron/gold carbide clusters containing Fe 5Au or Fe 5Au 2 skeletons: X-ray crystal structure of [Fe 5CAu 2(CO) 14(dppm)

The reaction of (NEt 4) 2[Fe 5C(CO) 14] with (AuCl) 2(diphos) depends on the stoichiometry of the process. Thus, with a 1:1 molar ratio, the cluster [Fe 5CAu 2(CO) 14(diphos)] (diphos=dppm, 1; dppe, 2; dppp, 3) was obtained. The X-ray crystal structure of 1 revealed that the metal core can be described as a square-based pyramid of Fe atoms and a trigonal bipyramid, with two Fe and one Au atoms at the vertices of the base and one Au and one Fe atoms at the apices, sharing a triangular face of Fe atoms. However, the use of a 2 (iron anion):1 (gold derivative) molar ratio yielded the cluster (NEt 4) 2[{Fe 5CAu(CO) 14} 2(diphos)] (diphos=dppm, 4; dppe, 5; dppp, 6), in which two octahedral Fe 5Au metal cores are linked by the diphosphine. On reacting with ClAuPR 3, the latter derivative underwent an unusual ligand redistribution process.

Four-Coordinate Gold(I), Silver(I), and Copper(I) Complexes with a Large-Span Chiral Ditertiary Phosphine Ligand.

The ligand L = Ph(2)PCH(2)CHEtOPPh(2) (R,S) with two chemically different donor sites and a center of chirality in the middle of the loop connecting the phosphorus atoms has been chosen for the preparation of a series of gold(I), silver(I), and copper(I) complexes. The ligand-to-metal ratio was allowed to vary between 2:1, 1:1, and 1:2. The 1:1 complexes [LAuX](2) with X = Cl, Br, I, and SCN have been found to be components of solution equilibria (in di- or trichloromethane) of various cyclic dinuclear isomers involving also several complexes generated in ligand redistribution processes. However, single crystals (X = Cl, Br) obtained from these solutions are composed solely of centrosymmetrical dimers where the two metal atoms are part of 12-membered rings and are bridged transannularly by two halogen atoms. By symmetry, the metal bridging by the two ligands L follows a head-to-tail pattern and involves a pair of enantiomers of L. The silver compound [LAgClO(4)](2) has an analogous structure with the silver atoms attaining coordination number 4 by perchlorate bridging. The copper complex [LCuCl](2) is a tricyclic binuclear compound where each copper atom is chelated by an individual ligand L and doubly halogen bridged with the second metal atom. The 2:1 complex [L(2)Au]Cl is assigned a bis-chelated structure with the tetracoordinated metal atom as a spiro center of two six-membered rings. The solution (31)P NMR spectra show the presence of various stereoisomers which are readily identified via the strong couplings mediated by the metal center. Only small J(P, P') values would be expected for P-P' coupling along the ligand PCCOP' loops. The spectrum of the dinuclear 1:2 complex L(AuCl)(2) features only two singlet (31)P resonances.

New CpCrCl 2(PR 3) complexes: physical properties and reduction chemistry

Compounds CpCrCl 2L ( L = PMe 2 Ph, 1, PMePh 2, 2; PPh 3, 3 ) have been prepared. Their magnetic moment is in accord with the presence of three unpaired electron and a variable temperature 1H NMR investigation of 1 shows Curie-Weiss behavior. The 1H NMR, EPR and UV-visible spectra are in agreement with those of other previously reported compounds of the same family. An electrochemical investigation shows the accessibility of an irreversible reduction process. A parallel sodium reduction investigation of complexes CpCrCl 2L (L = PMe 3 and η 1-dppe) suggests tjat the reduction process is followed by immediate chloride loss, and then by a ligand redistribution process to afford chromocene and unstable inorganic phosphine complexes of Cr(II).

Instability of 15-electron [formula omitted] derivatives. X-ray structure of Cp ☆MoCl 2(PMe 2Ph) 2 and [Cp ☆MoCl 2(PMe 2Ph) 2]AlCl 4

The complex Cp ★MoCl 2(PMe 2Ph) 2 (Cp ★ = η 5C 5Me 5) has been obtained in good yield from Cp ☆MoCl 4, PMe 2Ph 2, and Na in the appropriate stoichiometric ratio, and it is also obtained by a ligand redistribution process after reduction of Cp ☆MoCl 3- (PMe 2Ph) with Na. This compound is oxidized by the CH 2Cl 2 solvent in the presence of AlCl 3 to afford the salt [Cp ☆MoCl 2(PMe 2Ph) 2AlCl 4. Both compounds have been characterized crystallographically and by 1H-NMR spectroscopy. The reasons for the instability of 15-electron Cp ☆MoCl 2L complexes are discussed. The 1H-NMR resonance data for Cp ☆ MoCl 2 L 2 ( L = PMe 3, PMe 2 Ph) and [Cp ☆MoCl 2(PMe 2Ph) 2] + are also discussed.

Anionic and neutral spiked triangle clusters of mercury: a comparative study of the metal ligand redistribution process

The action of the NEt + 4 salts of the anions [Fe 2(CO) 8] 2− and [Fe 2(CO) 6(μ-CO)(μ-PPh 2)] − on ClHg-m complexes (m = Mo(CO) 3Cp, W(CO) 3Cp, Mn(CO) 5, Co(CO) 4, and Fe(CO) 2Cp) has been investigated. In the first case, anionic spiked triangle clusters of formula [Fe 2(CO) 6(μ-CO) 2(μ-Hg-m)] − were obtained in high yields, and no metal ligand redistribution reactions were detected. However, the action of [Fe 2(CO) 6(μ-CO)(μ-PPh 2)] − on the same bimetallic transition metal-mercury compounds gave the neutral species [Fe 2(CO) 6(μ-CO)(μ-PPh 2)(μ-Hg-m)], which spontaneously redistributed to [Hg{Fe 2(CO) 7(μ-PPh 2)} 2] and m 2Hg. Only the molybdenum derivative could be isolated in pure form. The different behaviour of the two series of complexes in the redistribution process is discussed.

Chemistry of vinylidene complexes. V. The ligand substitution reactions at the platinum atom in complexes Cp(CO) 2MnPt(μ-CCHPh)L 2

The dimetal μ-vinylidene complexes Cp(CO) 2-MnPt(μ-CCHPh)L 2 (L = PPh 3 or P(OPr i) react with nucleophylic molecules (phosphines, phosphites or CO), without cleavage of a dimetallacycle, to afford the products of substitution of platinum-bound terminal ligands with geometry depending on the nature of an entering ligand. The reaction of Cp(CO) 2MnPt(μ-CCHPh)(PPh 3) 2 and P(OPr i) gives Cp(CO) 2MnPt(μ-CCHPh)[P(OPr i) 3] 2 and Cp(CO) 2- MnPt(μ-CCHPh)[P(OPr i) 3](PPh 3) with the P(OPr i) 3 group cis to the μ-C atom. The latter is also formed by treating Cp(CO) 2MnPt(μ-CCCHPh)[P(OPr i) 3] 2 with PPh 3, and as a result of the ligand exchange reaction between bis-phosphine and bis-phosphite compounds. The last ligand redistribution process is reversible, and an equilibrium between all three of the above complexes exists in solution. Treatment of Cp(CO)MnPt(μ-CCHPh)L 2 with Co 2(CO) 8 yields the tricarbonyl complexes Cp(CO) 2- MnPt(μ-CCHPh)(L)(CO) with the platinum-bound Co group trans to μ-C. All studied reactions are stereoselective, and no mixed-ligand complexes isomeric to the above species have been detected. The IR and 1H, 13P NMR spectra of the new complexes are discussed.