Enzymatic desymmetrization of meso cis-2,6- and cis,cis-2,4,6-substituted piperidines. Chemoenzymatic synthesis of (5S,9S)-(+)-indolizidine 209D

The stereoselective acylation of meso piperidines 3a,b by vinyl acetate (solvent and acyl donor) in the presence of Candida antarctica lipase gave the corresponding (2S,6R) and (2S,4R,6R) monoesters 2a,b in high enantiomeric purity. (5S,9S)-(+)-Indolizidine 209D was prepared in eight steps from (2S,6R)-2a.     

Bilitrienones from the chemical oxidation of dodecasubstituted porphyrins

The structure of the ring-opened product from direct oxidation of meso-tetra-arylporphyrins has been controversial for three decades. Herein we show that bilitrienones 2 are obtained from oxidation of metal-free dodecasubstituted porphyrins 1 in the presence of sodium nitrite, trifluoroacetic acid, and air oxygen. The presence of the para-nonyl groups in 1b stabilized the corresponding bilitrienone 2b, which was characterized by X-ray crystallography. In the absence of the para-nonyl groups bilitrienone 2a undergoes a rapid hydration reaction, giving biladienone 3a as the major isolated product. The molecular structures of 2b and 3a, and the photochemical isomerization of 3a are discussed.     

Platinum thiosemicarbazide and thiourea complexes: the crystal structure of [PtCl(dppe){SC(NHMe)NHNMe2-S}](PF6) and the influence of intramolecular hydrogen bonding on ligand co-ordination mode

The reaction of [PtCl₂(dppe)] [dppe=1,2-bis(diphenylphosphino)ethane] with two equivalents of the thioureas NHRC(S)NHR (R=H, Me, Et) in the presence of NH₄PF₆ led to substitution of both chlorides and formation of the complexes [Pt(dppe){SC(NHR)₂}₂](PF₆)₂ (1a, R=H; 1b, R=Me; 1c, R=Et). In contrast, the reaction of [PtCl₂(dppe)] with one equivalent of the potentially bidentate thiosemicarbazides NHRC(S)NHNR′₂ (R=Me, R′=H; R=Et, R′=H; R=Ph, R′=H; R=Me, R′=Me) in the presence of NH₄PF₆ led to substitution of only one chloride and formation of the complexes [PtCl(dppe){SC(NHR)NHNR₂′-S}](PF₆) (2a, R=Me, R′=H; 2b, R=Et, R′=H; 2c, R=Ph, R′=H; 2d, R=Me, R′=Me). An X-ray analysis of complex 2d revealed that an intramolecular N–H⋯Cl hydrogen bond [N(2)⋯Cl(1)=3.29(2) Å] helps to stabilise the monodentate co-ordination mode. The chloride ligand can be abstracted from complex 2d by treatment with TlPF₆, and this reaction led to formation of [Pt(dppe){SC(NHMe)NHNMe₂-S,N}](PF₆)₂ 3d. Reaction of [PtCl₂(dppe)] with unsubstituted thiosemicarbazide NH₂C(S)NHNH₂ in the presence of NH₄PF₆ resulted in a mixture of products containing mono- and bidentate co-ordinated ligands, [PtCl(dppe){SC(NH₂)NHNH₂-S}](PF₆) 2e and [Pt(dppe){SC(NH₂)NHNH₂-S,N}](PF₆)₂ 3e. [PtCl₂(dppe)] also reacts with two equivalents of NHMeC(S)NHNMe₂ in the presence of NH₄PF₆ to yield [Pt(dppe){SC(NHMe)NHNMe₂-S}₂](PF₆)₂ 1d, in which the thiosemicarbazide is acting as an S-donor, directly analogous to the thiourea ligands in complexes 1a–c.     

Stereochemical studies—LVII: Synthesis of optically active compounds by the novel use of meso-compounds—1. Efficient synthesis of two structural types of optically pure prostaglandin intermediates

With an aim to overcome several inefficient aspects of ordinary methods of preparing optically active compounds, we have developed a new method which recommends utilization of symmetrically functionalized meso-compounds in place of racemic compounds.As shown in Scheme 1, when the mesa-compound (I) is monofunctionalized by an optically active functional group (A) and each of the formed diastereomers (II and III) is subjected to further chemical elaborations including protective group transposition, it is theoretically possible to convert the total amount of the starting material (I) into the requisite optically pure product (VI or VII) by selecting synthetic schemes.By employing this novel concept, two structural types of the prostaglandin intermediates ((?)- and ( + )-2a,b) have been prepared from the meso-diols (1a, b) by way of the two diastereomeric monoesters (13a, b and 14a, b) which are produced by the reactions of 1a, b with N-mesyl- and N-phthaloyl-(S)-phenylalanyl chloride (3a, b).     

Lipase mediated enantiomer and diastereomer separation of 2,2′-[1,2- and 1,3-phenylenebis(oxy)]dicyclohexanols

Separation of diastereomeric and enantiomeric mixtures of 2,2′-[1,2- and 1,3-phenylenebis(oxy)]dicyclohexanols rac-3a and meso-3a, and rac-3b and meso-3b—resulting from the reactions of pyrocatechol 1a and resorcinol 1b with cyclohexene oxide 2—were performed using acetylation catalyzed by the highly stereoselective Candida antarctica lipase B (Novozym 435). The absolute configurations of the resulting diols (S,S,S,S)-3a,b, monoacetates (R,R,S,S)-4a,b and diacetates (R,R,R,R)-5a,b were assigned on the basis of the steric analogy to the acetylation of racemic trans-2-phenoxycyclohexanol rac-6 with the same enzyme resulting in the known acetate (−)-(R,R)-7.     

Chelating diamide complexes of titanium: new catalyst precursors for the highly active and living polymerization of α-olefins

The reaction of RHN(CH₂)₃NHR (1a,b) (a, R=2,6-ⁱPr₂C₆H₃; b, R=2,6-Me₂C₆H₃) with 2 equiv of BuLi followed by 2 equiv of ClSiMe₃ yields the silylated diamines R(Me₃Si)N(CH₂)₃N(SiMe₃)R (3a,b). The reaction of 3a,b with TiCl₄ yields the dichloride complexes [RN(CH₂)₃NR]TiCl₂ (4a,b) and two equiv of ClSiMe₃. An X-ray study of 4a (P2₁/n, a=9.771(1) Å, b=14.189(1) Å, c=21.081(2) Å, β=96.27(1)°, V=2905.2(5) ų, Z=4, T=25°C, R=0.0701, R_w=0.1495) revealed a distorted tetrahedral geometry about titanium with the aryl groups lying perpendicular to the TiN₂-plane. Compounds 4a,b react with 2 equiv of MeMgBr to give the dimethyl derivatives [RN(CH₂)₃NR]TiMe₂ (5a,b). An X-ray study of 5b (P2₁2₁2₁, a=8.0955(10) Å, b=15.288(4) Å, c=16.909(3) Å, V=2092.8(7) ų, Z=4, T=23°C, R=0.0759, R_w=0.1458) again revealed a distorted tetrahedral geometry about titanium with titanium–methyl bond lengths of 2.100(9) Å and 2.077(9) Å. These titanium dimethyl complexes are active catalysts for the polymerization of 1-hexene, when activated with methylaluminoxane (MAO). Activities up to 350,000 g of poly(1-hexene)/mmol catalyst·h were obtained in neat 1-hexene. These systems actively engage in chain transfer to aluminum. Equimolar amounts of 5a or 5b and B(C₆F₅)₃ catalyze the living aspecific polymerization 1-hexene. Polydispersities (M_w/M_n) as low as 1.05 were measured. Highly active living systems are obtained when 5a is activated with {Ph₃C}⁺[B(C₆F₅)₄]⁻. A primary insertion mode (1,2 insertion) has been assigned based on both the initiation of the polymer chain and its purposeful termination with iodine.     

Octahedral bis(acetylide) and bis(diacetylide) complexes of ruthenium(II) with linear C2MC2 and C4MC4 chains: The first X-ray structures of the all trans bis(acetylides) Ru(CO)2(CCPh)2(PEt3)2 and Ru(CO)2(CCH)2(PEt3)2

Bis(acetylides) and bis(diacetylides) of ruthenium(II), trans-Ru(CO)₂(PEt₃)₂(CCR)₂ (1) (1a, R  Ph; 1b, R  ^tBu; 1c, R  SiMe₃; 1d, R  H) and trans-Ru(CO)₂(PEt₃)₂(CCC CR)₂ (2) (2a, R  SiMe₃; 2b, R  H) have been synthesized and characterised. The first single crystal X-ray analyses of these all trans-acetylides have revealed linear C₂RuC₂ chains in 1a and 1d.     

Elektrochemische synthesen: XXII. Die kathodische reduktion von pentacarbonyl-chrom-halogenphosphanen

The cathodic reduction of the trihalophosphane complexes (CO)₅CrPX₃ (1a, X = Cl; 1b, X = Br) leads to the binuclear complexes (CO)₅ Cr(X₂PPX₂)Cr(CO)₅, (2a, X = Cl; 2b, X = Br). Reductive dehalogenation of coordinated organodihalophosphanes, (CO)₅CrPRX₂ (3a, R = Me, X = Cl; 3b, R = Ph, X = Cl; 3c, R = Me, X = Br; 3d, R = Ph, X = Br), in the presence of dimethyldisulfane yields bis(methylthio)organophosphane complexes, (CO)₅CrPR(SCH₃)₂ (5a, R = Me; 5b, R = Ph). The phosphinidene complexes (CO)₅ CrPR are discussed as the reactive intermediates.The organodibromophosphane complexes 3c and 3d can also be partially reduced in the presence of dimethyldisulfane, and (CO)₅CrPBrR(SCH₃) (7a, R = Me; 7b, R = Ph) is obtained. Radical intermediates are probable.     

Structural studies of phosphor-1,1-diselenoato Mn(I) and Re(I) complexes

Mononuclear complexes of the type, M(CO)₄[Se₂P(OR)₂] (M = Mn, R = ⁱPr, 1a; Et, 1b; M = Re, R = ⁱPr, 3a; Et, 3b) can be prepared from either [-Se(Se)P(OⁱPr)₂]₂ (A) or [Se{-Se(Se)P(OEt)₂}₂] (B) with M(CO)₅Br. O,O′-dialkyl diselenophosphate ([(RO)₂PSe₂]^-, abbreviated as dsep) ligands generated from A and B act as a chelating ligand in these complexes. Upon refluxing in acetonitrile, these mononuclear complexes yield dinuclear complexes with a general formula of [M₂(CO)₆{Se₂P(OR)₂}₂] (M = Mn, R = ⁱPr, 2a; Et, 2b; M = Re, R = ⁱPr, 4a; Et, 4b). Dsep ligands display a triconnective, bimetallic bonding mode in the dinuclear compounds and this kind of connective pattern has never been identified in any phosphor-1,1-diselenoato metal complexes. Compounds 2b, 3b, and 4 are structurally characterized. Compounds 2b and 3b display weak, secondary Se?Se interactions in their lattices.     

Preparation of cobalt-containing bulky monodentate phosphines with electron-withdrawing/donating substituents on bridged arylethynyl and their applications in Suzuki coupling reactions

Several cobalt-containing bulky monodentate phosphines (μ-PPh₂CH₂PPh₂)Co₂(CO)₄(μ,η-(^tBu)₂PCC(C₆H₄R)) (4a: R=H; 4b: R=p-F; 4cp: R=p-CF₃; 4cm: R=m-CF₃; 4d: R=p-OMe) were prepared from the reactions of (^tBu)₂PCC(R-C₆H₄) (2a: R=H; 2b: R=p-F; 2cp: R=p-CF₃; 2cm: R=m-CF₃; 2d: R=p-OMe) with Co₂(CO)₆(μ-PPh₂CH₂PPh₂) 3. Further reactions of 4a, 4b, 4cp, 4cm, and 4d with Pd(OAc)₂ yielded unique palladium complexes (μ-PPh₂CH₂PPh₂)Co₂(CO)₄(μ,η-(^tBu)₂PCC(C₆H₃R)-κC¹)Pd(μ-OAc) (5a: R=H; 5b: R=p-F; 5cp: R=p-CF₃; 5cm: R=m-CF₃; 5d: R=p-OMe, respectively). The strong electron-withdrawing substituents, -F and -CF₃, assist the ortho-metalation process during the formation of 5b, 5cp, and 5cm. The more positively charged palladium center in 5b (or 5cp, 5cm) enhances the probability for PhB(OH)₃⁻ to attack the metal center and the rate of reduction thereafter. DFT studies on the charges of these palladium centers support this assumption. The enhancement of the reaction rates of the Suzuki-Miyaura cross-coupling reactions using 5b, 5cp, and 5cm is thereby attributed to this effect.     

New cyclometalated palladium(II) complexes with iminophosphines: Crystal structures of [Pd(C^N)(o-Ph2PC6H4–CH=NR)][PF6] (C^N=azobenzene,R=Et; C^N=2-phenylpyridine,R=Me)

The synthesis of new cyclometalated compounds of palladium(II) with the mixed-donor bidentate ligands o-Ph₂PC₆H₄–CH=NR is described. Two series of complexes [Pd(C^N)(o-Ph₂PC₆H₄–CH=NR)][PF₆] have been prepared using either azobenzene or 2-phenylpyridine as cyclometalated ligands [C^N=azobenzene (azb); R=Me (1a), Et (2a), ⁿPr (3a), ⁱPr (4a), ^tBu (5a), Ph (6a), NH–Me (7a); C^N=2-phenylpyridine (phpy); R=Me (1b), Et (2b), ⁿPr (3b), ⁱPr (4b), ^tBu (5b), Ph (6b), NH–Me (7b)]. The new complexes were characterized by partial elemental analyses and spectroscopic methods (IR, FAB, ¹H and ³¹P NMR). The molecular structures of compounds 2a (monoclinic, P 2₁/n) and 1b (monoclinic, C 2/c) have been determined by a single-crystal diffraction study. In both cases this technique revealed the relative trans configuration between the phosphorus atom and the nitrogen atom of the ortho-metalated ligand.     

Mehrfachbindungen zwischen hauptgruppenelementen und übergangsmetallen: XXXVI. Metallorganische oxide der vanadium-reihe: derivate der schlüsselverbindung (η5-C5H5)VOCl2

The synthesis of the organovanadium(V) oxide (η⁵-C₅H₅)VOCl₂ (2a) from the low-valent precursor compound (η⁵-C₅H₅)V(CO)₄ (1a) has been applied to the permethylated derivative of composition (η⁵-C₅Me₅VOCl₂ (2b). Exchange of bromine for chlorine in oxodichlorides 2a and 2b is effected by boron tribromide, yielding the oxodibromide derivatives of composition (η⁵-C₅R₅)VOBr₂ (R = H, 3a; R = CH₃, 3b). The methoxy derivatives 4a and 4b are synthesized directly from the dichloro precursors 2a and 2b, respectively, by treatment with a slight excess of sodium methoxide. Diarylvanadium(V) compounds (η⁵-C_5R)VOX₂ (e.g., R = CH₃, X = C₆H₅; 5b), are obtained from 2a,2b via the Grignard route. ⁵¹V NMR spectroscopy is an easy and powerful method of detecting novel organic vanadium oxides since the chemical shifts vary greatly even with small changes in the ligands attached to the metal.     

Cobalt metallocycles: XIII. Preparation and x-ray crystallography of cobaltacyclopentadiene and dinuclear cobalt complexes

(η-Cyclopentadienyl)(triphenylphosphine)cobaltacyclopentadienes having an electron withdrawing substituent on the cyclopentadienyl ring, (η-C₅H₄R)(PPh₃)($\text{CoCHCHC}$H) (1b: R = COOMe; 1c: R = COMe), were prepared in reasonable yields by treatment of a solution of (η-C₅H₄R)(PPh₃)₂Co with acetylene. A non-substituted cyclopentadienyl analog (1a: R = H) was also isolated in low yield according to a similar procedure. Novel dinuclear complexes were also formed as by-products and the structure of (η-C₅H₄R)Co(PPh₂$\text{C}{}_6\text{H}{}_4\text{)(μ-C}$Me)Co(η-C₅H₄R) (2b: R = COOMe), having a μ₂,η³-benzyl moiety, was determined by an X-ray crystallographic analysis. The X-ray analyses of 1a and 1b were also carried out. Crystals of 1a are monoclinic, space group Pa, a 8.529(3), b 16.010(6), c 8.028(4) Å, β 100.31(3)°, Z = 2; crystals of 1b are monoclinic, space group P2₁/a, a 8.327(2), b 36.468(7), c 8.021(1) Å, β 98.75(2)°, Z = 4; and crystals of 2b are monoclinic, space group P2₁/c, a 10.681(2), b 30.722(7), c 8.912(1) Å, β 93.55(1)°, Z = 4. They have been refined to R = 0.034, 0.047 and 0.050, respectively.     

Synthesis,structural characterisation and reactivity of molybdenum half-sandwich complexes containing keto- and amido-phosphines

The keto-functionalised N-pyrrolyl phosphine ligand PPh₂NC₄H₃{C(O)CH₃-2} L¹ reacts with [MoCl(CO)₃(η⁵-C₅R₅)] (R=H, Me) to give [MoCl(CO)₂(L¹-κ¹P)(η⁵-C₅R₅)] (R=H 1a; Me 1b). The phosphine ligands PPh₂CH₂C(O)Ph (L²) and PPh₂CH₂C(O)NPh₂ (L³) react with [MoCl(CO)₃(η⁵-C₅R₅)] in an analogous manner to give the compounds [MoCl(CO)₂(L-κ¹P)(η⁵-C₅R₅)] (L=L², R=H 2a, Me 2b; L=L³, R=H 3a, Me 3b). Compounds 1–3 react with AgBF₄ to give [Mo(CO)₂(L-κ²P,O)(η⁵-C₅R₅)]BF₄ (L=L¹, R=H 4a, Me 4b; L=L², R=H 5a, Me 5b; L=L³, R=H 6a, Me 6b) following displacement of chloride. The X-ray crystal structure of 4a revealed a lengthening of both Mo–P and CO bonds on co-ordination of the keto group. The lability of the co-ordinated keto or amido group has been assessed by addition of a range of phosphines to compounds 4–6. Compound 4a reacts with PMe₃, PMe₂Ph and PMePh₂ to give [Mo(CO)₂(L¹-κ¹P)(L)(η⁵-C₅H₅)]BF₄ (L=PMe₃ 7a; PMe₂Ph 7b; PMePh₂ 7c) but does not react with PPh₃, 5a reacts with PMe₂Ph, PMePh₂ and PPh₃ to give [Mo(CO)₂(L²-κ¹P)(L)(η⁵-C₅H₅)]BF₄ (L=PMe₂Ph 8b; PMePh₂ 8c; PPh₃ 8d), and 6a reacts with PMe₃, PMe₂Ph, PMePh₂ and PPh₃ to give [Mo(CO)₂(L³-κ¹P)(L)(η⁵-C₅H₅)]BF₄ (L=PMe₃ 10a; PMe₂Ph 10b; PMePh₂ 10c; PPh₃ 10d). No reaction was observed for the pentamethylcyclopentadienyl compounds 4b–6b with PMe₃, PMe₂Ph, PMePh₂ or PPh₃. These results are consistent with the displacement of the co-ordinated oxygen atom being influenced by the steric properties of the P,O-ligand, with PPh₃ displacing the keto group from L² but not from the bulkier L¹. In the reaction of [Mo(CO)₂(L²-κ²P,O)(η⁵-C₅H₅)]BF₄ (5a) with PMe₃ the phosphine does not displace the keto group, instead it acts as a base, with the only observed molybdenum-containing product being the enolate compound [Mo(CO)₂{PPh₂CHC(O)Ph-κ²P,O}(η⁵-C₅H₅)] 9. Compound 9 can also be formed from the reaction of 2a with BuLi or NEt₃, and a single crystal X-ray analysis has confirmed the enolate structure.     

Synthesis and study of tetraamminecobalt hydrogen hexamolybdometalates(III)

Tetraamminecobalt hydrogen hexamolybdoferrate [Co(NH₃)₄] · H[FeMo₆O₁₈(OH)₆] · 6H₂O (I) and tetraamminecobalt hydrogen hexamolybdogallate(III) [Co(NH₃)₄] · H[GaMo₆O₁₈(OH)₆] · 6H₂O (II) were synthesized and studied by mass spectrometry, thermogravimetry, IR spectroscopy, and X-ray diffraction. Crystals of I and II are monoclinic; a = 16.21 Å, b = 5.43 Å, c = 12.32 Å, β = 119.63°, V = 1092.11 ų, ρ_calcd = 2.21 g/cm³, and Z = 1 for I; a = 16.24 Å, b = 5.59 Å, c = 12.29 Å, β = 119.79°, V = 1064.05 ų, ρ_calcd = 2.15 g/cm³, and Z = 1 for II. Compounds I and II were used as catalysts for soft oxidation of natural gas.     

Metallacumulenylidene complexes in the [(η5-C5Me5)(η2-dppe)Fe(=C(=C)nR2)]X (n = 0, 1, 2) series: investigations of the iron-carbon bonding by Mössbauer spectroscopy and X-ray analyses

The synthesis of the iron allenylidene complexes [(η⁵-C₅Me₅)(η²-dppe)Fe(=C=C=C(Ph)Ph)][X] (5a, X = PF₆, 95%; 5b, X = BPh₄, 91%; dppe = 1,2-bis(diphenylphosphino)ethane) was achieved by reacting the complex (η⁵-C₅Me₅)(η²-dppe)FeCl (10) with 1 equiv of 1,1-diphenyl-prop-2-yn-1-ol in methanol in the presence of KPF₆ or NaBPh₄. Surprisingly, when the reaction was carried out in the presence of the tetraphenylborate anion, the final product contained both 5b and the hydroxyvinylidene [(η⁵-C₅Me₅)(η²-dppe)Fe(=C=C(H)C(OH)(Ph)₂)][BPh₄] (14b) in the 1:1 ratio. Further treatment of the mixture with Amberlyst 15 in methanol provided the allenylidene 5b as a pure sample. The allenylidene complexes [(η⁵-C₅Me₅)(η²-dppe)Fe(=C=C=C(Me)Ph)][PF₆] (6) and [(η⁵-C₅Me₅)(η²-dppe)Fe(=C=C=C(Me)Et)][PF₆] (7) were prepared according to the same procedure and they were isolated as purple powders in 90% yield. The X-ray crystal structures were determined for the vinylidene complexes [(η⁵-C₅Me₅)(η²-dppe)Fe(=C=CH₂)][PF₆] (3) and [(η⁵-C₅Me₅)(η²-dppe)Fe(=C=C(Ph)H)][PF₆] (4), and the allenylidene derivative 5a. In the homogeneous series of complexes [(η⁵-C₅Me₅)(η²-dppe)Fe(=(C)_n(R)R’)][PF₆], (n = 1, R = H, R′ = Me, X = PF₆, 1; n =1, R = H, R’ = OMe, X = PF₆, 2a; n = 1, R = H, R’ = OMe, X = CF₃OSO₂, 2b; n = 2, R = R′ = H, X = PF₆, 3; n = 2, R = H, R′ = Ph, X = PF₆, 4; n = 3, R = R′ = Ph, X = PF₆, 5a; n = 3, R = R′ = Ph, X = BPh₄, 5b; n = 3, R = Me, R′ = Ph, X = PF₆, 6; n = 3, R = Me, R′ = Et, X = PF₆, 7; n = 3, R = Me, R′ = OMe, X = BPh₄, 8), an empiric relationship between the Mössbauer parameters, δ and QS, was found. This observation would indicate that the positive charge on the iron nucleus decreases with the Fe=C bond order. Moreover, in this series of iron cumulenylidene derivatives, comparison of the variation of the metal–carbon bond distances determined by X-ray analyses with the Mössbauer QS values allows the observation of a linear correlation (R = 0.99). To cite this article: G. Argouarch et al., C. R. Chimie 6 (2003).     

Redox reactions involving the indium(III) catecholate complexes

Indium catecholate complexes 3,6-CatInR (3,6-Cat is the 3,6-di-tert-butyl-o-benzoquinone dianion (3,6-Q), R = Me (I) and Et (II)) are synthesized by the exchange reaction between RInI₂ and thallium catecholate 3,6-CatTl₂. Compounds I and II are trimeric in both the solution and crystalline state. The oxidation of compound I and earlier described complex [3,6-CatInI(THF)]₂ (THF is tetrahydrofuran) by various substrates (iodine, 3,6-Q, and tetramethylthiuram disulfide) is studied. Different indium(III) o-semiquinone complexes are the reaction products, depending on the reaction conditions.     

Diiron-aminocarbyne complexes with amine or imine ligands: C-N coupling between imine and aminocarbyne ligands promoted by tolylacetylide addition to [Fe2{μ-CN(Me)R}(μ-CO)(CO)(NHCPh2)(Cp)2][SO3CF3]

A terminally coordinated CO ligand in the complexes [Fe₂{μ-CN(Me)R}(μ-CO)(CO)₂(Cp)₂][SO₃CF₃] (R = Me, 1a; R = Xyl, 1b; Xyl = 2,6-Me₂C₆H₃), is readily displaced by primary and secondary amines (L), in the presence of Me₃NO, affording the complexes [Fe₂{μ-CN(Me)R}(μ-CO)(CO)(L)(Cp)₂][SO₃CF₃] (R = Me, L = NH₂Et, 4a; R = Xyl, L = NH₂Et, 4b; R = Me, L = NH₂Prⁱ, 5a; R = Xyl, L = NH₂Prⁱ, 5b; R = Xyl, L = NH₂C₆H₁₁, 6; R = Xyl, L = NH₂Ph, 7; R = Xyl, L = NH₃, 8; R = Me, L = NHMe₂, 9a; R = Xyl, L = NHMe₂, 9b; R = Xyl, = NH(CH₂)₅, 10). In the absence of Me₃NO, NH₂Et gives addition at the CO ligand of 1b, yielding [Fe₂{μ-CN(Me)(Xyl)}(μ-CO)(CO){C(O)NHEt}(Cp)₂] (11). Carbonyl replacement is also observed in the reaction of 1a-b with pyridine and benzophenone imine, affording [Fe₂{μ-CN(Me)R}(μ-CO)(CO)(L)(Cp)₂][SO₃CF₃] (R = Me, L = Py, 12a; R = Xyl, L = Py, 12b; R = Me, L = HNCPh₂, 13a; R = Xyl, L = HNCPh₂, 13b). The imino complex 13b reacts with p-tolylacetylide leading to the formation of the μ-vinylidene-diaminocarbene compound [Fe₂{μ-η¹:η²- CC(Tol)C(Ph)₂N(H)CN(Me)(Xyl){(μ-CO)(CO)(Cp₂)] (15) which has been studied by X-ray diffraction.     

Further studies on the taumerization of the hydrido (alkynyl) cluster Ru3Pt(μ-H) {μ4-ν2-C ≡ C1Bu} (CO)9(L2) to the vinylidene cluster Ru3Pt{μ4-ν2-C ≡ C(H)tBu} (CO)9(L2): X-ray structures of Ru3Pt(μ-H){μ4-ν2-C = C(H)tBu} (CO)9(L2); L2 = dppet,dppp, andS,S-dppb

The first order rate constants for the tautomerization of the hydrio(alkynyl) clusters Ru₃Pt(μ-H){μ₄-ν²-C ≡ C¹Bu}(CO)₉(L₂);1a: L₂ = dppe,1b; L₂ = dppet,1c; L₂ = dppp and1d; L₂ =S,S-dppb to the corresponding vinylidene clusters Ru₃Pt{μ₄-ν²-C = C(H)^tBu}(CO)₉(L₂)2 have been measured, and they follow the orser1d <1a <1b ～1c. The reactions involving1a and1d exhibit an inverse kinetic deuterium isotope effect. The structures of1b, 2b, 2c, and2d were determined by X-ray crystallography, and are compared with those of1a and2a which have been previously reported. Crystal data for1b, space groupPbca,a = 13.338(4) Å,b = 17.771(6) Å,c = 36.092(8) Å,Z = 8,R(R _w) = 0.059(0.058) for 2342 absorption corrected, observed data; for2b, space group P2₁/n,a = 10.566(2) Å,b = 20.234(5) Å,c = 20.270(3) Å,β = 96.11(1)°,Z = 4,R(R _w) = 0.043(0.053) for 5865 absorption corrected, observed data; for2c, space group P2₁/n,a = 14.211(5) Å,b = 19.534(2) Å,c = 15.870(2) Å,β = 100.81(2)°,Z = 4,R(R _w) = 0.055(0.031) for 6566 absorption corrected, observed data: for2d, space group P2₁2₁2₁,a = 12.309(4) Å,b = 19.047(6) Å,c = 19.206(4) Å,Z = 4,R(R _w) = 0.055(0.053) fpr 2151 absorption corrected, observed data. The fluxional behavior of1d and1e (which consists of two interconverting isomers) has been examined by variable temperature¹³C NMR spectroscopy and by³¹P EXSY.     

Chlorine reaction with platinum triamine [Pt(N,N-DimeTm)PyCl3]Cl (N,N-DimeTm = (CH3)2N(CH2)3NH2). Crystal structure of [Pt(N,N-DimeTm)Cl2], [Pt(N,N-DimeTm(Py)Cl3]Cl · H2O and [Pt{(CH3)2N(CH2)2C(O)NH}(Py)Cl3]

Treatment of platinum(II) diamine [Pt(N,N-DimeTm)Cl₂] (I) with pyridine gave tetramine [Pt(N,N-DimeTm)Py₂]Cl₂ (II); by oxidation with chlorine this was converted to Pt(IV) triamine, [Pt“(N,N-DimeTm(Py)Cl₃]Cl (III) with a six-membered chelate ring. According to X-ray diffraction data, the reaction of complex II with chlorine is accompanied by removal of the pyridine molecule from the trans-position to the NH₂ group of N,N-dimethyltrimethylenediamine. The reaction of complex III with chlorine at 20°C afforded a mixture of compounds (IV) and the complex [Pt“(CH₃)₂N(CH₂)₂C(O)NH”(Py)Cl₃] (V) with an amidate six-membered metal ring, dimethylpropioamide, which was also isolated upon refluxing a mixture of IV in an aqueous solution. The UV/Vis and IR spectra of the obtained complexes were studied, and X-ray diffraction analysis of I, III, and V was performed. The crystals of I are triclinic, space group P $ \bar 1 $ ; a = 7.6526(4) Å, b = 11.5571(6) Å, c = 12.4432(7) Å, α = 113.85(1)°, β = 96.54(2)°, γ = 106.78(2)°; Z = 4; R _hkl = 0.051. The crystals of III are monoclinic, space group C2/c; a = 36.715(2) Å, b = 7.8179(4) Å, c = 29.721(16) Å, β = 127.80(1)°; Z = 16; R _hkl = 0.036. The crystals of V are monoclinic, space group P2₁/n; a = 7.0398(6) Å, b = 27.458(2) Å, c = 7.687(6) Å, β = 106.270(1)°; Z = 4; R _hkl = 0.052.