O. A. Kizas

Protonation of triosmium clusters Os3(CO)9(μ−CO)(μ3−2σ,η2−HCCR) and Os3(μ−H)(CO)9(μ3−σ,2η2−CCR) (R = CH2OH, CMe2OH, C(Me) = CH2

Abstract Protonation of Os3(CO)(μ−CO(μ3−2σ,η2−HCCR) (R = CH2OH (1) R = CMe2OH (2) and Os3(μ−H)(CO)9(μ3−σ,2η2−CCR) (R = CH2OH (3), R = CMe2OH (4), R = C(Me) = CH2 (5)) affords cationic complexes with the 5e-and 6e-propargyl ligands [Os3(CO)9(μ−CO)(μ3−3σ,η2−HCCCR′2)]+ (R′ = H (6), R′ = Me ( 7 ) and [Os3(μ−H)(CO)9(μ3−2σ,2η2−CCR′2)+ ( R′ = H ( 8 ) , R′ = Me ( 9 ) respectively. Reactrions of the cationic complexes with PPh3 were studied. The treatment of solutions of complexes 6–9 with triphenylphosphine leads to the phosphonium derivatives of the Os3 clusters Os 3 ( CO ) 9 (μ 2 −2σ,η 2 - HC  CCR ′ 2 P + Ph 3 ) ( R ′ = H , (10); R ′ = Me, ( 11 )) as well as complexes Os 3 (μ- H(CO ) 9 (μ 3 −σ,2η 2 − P + Ph in3 CCCR ′ 2 ) ( R = H ( 12 , R ′ = Me ( 13 )) with the novel phosphonium allenyl ligand. The cluster Os3(CO)8(μ−CO){HC2[C(Me)CH2]COC[C(Me)CH2]CH} (4) synthesized and its X-ray study was carried out (R = 0.0504 for 5510 observed reflections). Crystals of 14 are triclinic, at 20°C: a = 8.591(2), b = 11.437(2), c = 12.642(3) A , α = 93.17(2), β = 104.67(2), γ = 101.83(2)°, V = 1168.6(4) A , d calc = 2.793 g cm −3 , Z = 2 , space group P 1 .

Intramolecular rearrangement of the bridging σ,π-acetylide ligand in the Os3H(CO)9(L)(μ-η2-CCPh) (L = CO, PMe2Ph) clusters and crystal structure of Os3H(CO)9(PMe2Ph)(μ-η2-CCPh)

Clusters Os3H(Cl)(CO)9(L) (L= CO, PMe2Ph) react with lithium phenyl-acetylide to yield Os3H(CO)9(L)(μ-η2-CCPh),which has a bridging acetylide ligand. The Os3H(CO)10(μ-η2-CCPh) complex (II) is fluxional owing to rapid π → σ, σ → π interchange of acetylide ligand between the bridged osmium atoms, whereas the phosphine-substituted derivative, Os3H(CO)9(PM2Ph)(μ-η2-CCPh) (III), is stereochemically rigid and exists at room temperature in two isomeric forms. These isomers have been isolated as solids and have been characterized by 1H and 31P{1H} NMR spectroscopy. According to the spectroscopic data, in the major (IIIa) and minor (IIIb) isomers the phosphine ligand is coordinated to the metal atom which is σ- or π-bonded to the bridging acetylide group, respectively. The isomerization of IIIb into IIIa occurs only at 80°C. The structure of IIIa has been confirmed by an X-ray diffraction study.

Coupling and annelation of two acetylide groups and alkyne molecules in the reaction of (OC)5ReCCPh with ferrocenylacetylene. Crystal and molecular structure of Re2(CO)7{C8H2Ph2(C5H4FeC5H5)2} · acetone

X-Ray diffraction study was carried out of the binuclear complex Re2(CO)7(C8)H2Ph2Fc2) (II), obtained in the reaction of (OC)5ReCCPh with ferrocenylacetylene FcCCH in refluxing toluene. Complex II crystallizes in the monoclinic space group P 21/n with a 20.363(5), b 10.121(2), c 22.952(7) A, β 112.49(2)°, V 4302(2) A3, and Z = 4. Compound II possesses a rhenacyclopentadiene ring, fused with the methylenecyclopentene moiety along the central CC bond, and π-bonded by the Re (CO)3 group. The hydrocarbon ligand of compound II is formed by condensation of two PhCC groups and two FcCCH molecules. Preparative methods of synthesis of (OC)5ReCCPh, (OC)5ReCCCO2Me and (OC)5ReCCSiMe3 are reported.

Formation of the triosmium μ-carbyne complex in the reaction of with dimethylphenylphosphine. X-ray structure of HOs3(CO)10{μ-CC(Ph)CC(Ph)Re(CO)4PMe2Ph}

Abstract The μ-acyl complex B″O (I) reacts with PMe 2 Ph to yield the allenyl-substituted μ-carbyne complex HOs 3 (CO) 10 {μ-CC(Ph)CC(Ph)Re(CO) 4 PMe 2 Ph} (II). Complex II has been characterized by an X-ray structural study.

On the possibility of a carbenium ion structure for the complexes [Os3H3(CO)9CCR2]+. Further application of the 187Os nucleus

Abstract In the 1H NMR spectrum of the complex [Os3H3(CO)9C C(CH 2 C H2]+ at 30°C, under conditions of rapid exchange, the single hydride resonance has two sets of satellites of equal intensity (separated by 32.0 and 28.8 Hz) caused by 187Os1H spin—spin coupling. The spectral data rule out the upright carbenium ion structure for the complex, and are consistent with the fluxional process involving hydrocarbon ligand rotation about the C C(CH 2 ) 2 C H2 axis in a tilted structure, with concomitant rotation of the Os3H3(CO)9 moiety.

Carbon–carbon bond formation by alkyne–µ,η2-acetylide and alkyne–CO coupling in the reaction of (OC)5MCCPH (M = MN, Re) with HOs3(CO)10(µ,η2-CCPh). X-Ray structure of HOs3Re(CO)14(C2Ph)2

Addition of (OC)5MCCPh (M = Mn,Re) to HOs3(CO)10(µ,η2-CCPh) leads to the formation of carbon–carbon bonds under mild conditions to yield metal cluster compounds HOs3M(CO)14(C2Ph)2; the cluster HOs3Re(CO)14(C2Ph) has been characterized by an X-ray structure analysis.

Crystal structure of OS3(CO)9(μ2-H)2(μ3-CCCH2CH2CH2)

An X-ray diffraction study of Os3(CO)9(μ2-H)2(μ3-CCCH2CH2CH2) at − 120°C (R = 0.039 for 2227 reflections) has revealed a μ3-η2-coordination of the methylenecyclobutane ligand, which bridges one OsOs bond via a methylidene carbon and is linked to the third Os atom by the C bond.

Reversible carbon—carbon bond formation by interconversion of CO and μ-acyl ligands on the face of an osmium cluster

Abstract Addition of PMe2Ph to the μ-acyl complex (III) induces carbon—carbon bond cleavage with conversion of the μ-acyl group to a terminal CO ligand and gives the zwitterionic compound [(OC)4 RePMe 2 Ph] + [Os 3 H(CO) 10 {μ-CC(Ph)C CPh}]− (IV). Facile elimination of CO (or PMe2Ph) from IV at the rhenium atom leads to the back formation of a μ-acyl group and gives the complex (V) or complex III.

Internuclear exchange of carbonyl groups in Os3(CO)12 : coupling constants J(187Os–13C) in trinuclear osmium carbonyls

The first measurement of nuclear spin-spin coupling constants 1J(187Os–13C) is reported for the complexes 187Os3(CO)12 and [187Os3H(CO)12]+; in the 13C n.m.r. spectrum of 187Os3(CO)12 at 150 °C, the averaged resonance is a 1:3:3:1 quadruplet, J(187Os–13C) 33 ± 1 Hz, which indicates that the intramolecular rearrangement occurs via an internuclear mechanism.

Synthesis and protonation of an OS3(μ-H)(CO)10(μ-σ,η2-C≡CCMe2OMe) cluster

Triosmium cluster Os3(μ-H)(CO)10(μ-σ-η2-C≡CC Me2OMe) (1) was obtained by treating OS3(μ-H)(μ-Cl)(CO)10 with LiC≡CCMe2OMe. The reaction of cluster1 with HBF4 · Et2O at −60 °C leads to the cationic complex [Os3(μ-H)(CO)10(μ-σ,σ,η2-C=C=C Me2)]+BF4− (2) with an allenylidene ligand. Thes1H and13C NMR spectra of complex2 reveal the temperature dependence caused by migration of hydrocarbon and carbonyl ligands. Thermodynamic parameters were obtained for be exchange process of the allenylidene ligand.