Luigi Busetto

Preparation and reactivity of some new azido-bridged complexes of Pd(II) and Pt(II)

Abstract Azido-bridged complexes of Pt(II) and Pt(II) of the type [(dieneOCH 3 )MN 3 ] 2 (M = Pd, Pt) and[(π-allyl)PdN 3 ] 2 have been prepared by methathetical reaction from their chloro-bridged congeners. The bridging azido group in these new complexes reacts with carbon monoxide to give the corresponding cyanato-bridged complexes, whereas with CS 2 , CF 3 CN and SCNC 6 H 5 undergoes 1,3-cycloaddition to form thiatriazolate or tetrazolate groups bridging in dimeric complexes of the type [(diene)CH) 3 )M(N 3 CS 2 ) (M = Pd, Pt), [(π-allyl)Pd(N 3 CS 2 ] 2 ,[(π-allyl)Pd(N 3 CF 3 CN)] 2 and [(π-allyl)Pd(N 3 SCNC 6 H 5 )] 2 . Preliminary results on the termal decomposition of the CS 2 adducts and on the reaction with COS are reported and discussed.

Reactions of cyclopentadienyliron carbonyl cations with amines

[C 5 H 5 Fe(CO) 2 L] + (L = CO, P(C 6 H 5 ) 3 ) reacts with primary and secondary amines to form carboxamido complexes, C 5 H 5 Fe(CO)(L)(CONHR): [C 5 H 5 Fe(CO) 2 L] + + 2RNH 2 → C 5 H 5 Fe(CO)(L)(CONHR) + RNH 3 + Their reaction with HCl removes the -NHR group from the carboxamido group: C 5 H 5 (CO)(L)(CONHR)+HCl → [C 5 H 5 Fe(CO) 2 L] + Cl − +RNH 2 The [C 5 H 5 Fe(CO) 3 ] + cation reacts with NaOCH 3 to form the alkoxycarbonyl derivative, C 5 H 5 Fe(CO) 2 C(O)OCH 3 , according to the equation: [C 5 H 5 Fe(CO) 3 ] + +OCH 3 − → C 5 H 5 Fe(CO) 2 C(O)OCH 3 A mechanism of nucleophilic attack at the carbonyl carbon is proposed for the formation of the carboxamido and alkoxycarbonyl derivatives. The properties of the new compounds are listed, and the carbonyl stretching frequencies are discussed.

Additions to the coordinated ethylene ligand in the [C5H5Fe(CO)2(C2H4)]+ complex

Abstract Reaction of [C5H5Fe(CO)2C2H4]+ with methylamine or methoxide ion (L) yields the stable σ-bonded carboniron complexes [C5H5Fe(CO)2(C2H4L)], which regenerate the original iron cationic complex when treated with hydrogen chloride. Reactions with other nucleophiles, such as N−3, NCO−, CN− have also been examined. With N−3 the nucleophilic attack occurs at the CO group to give the cyanato complex [C5H5Fe(CO)(C2H4)(NCO)], while with NCO− and CN− (X) ethylene is replaced to give [C5H5Fe(CO)2X] complexes.

Reactions of acetonitrile di-iron μ-aminocarbyne complexes; synthesis and structure of [Fe2(μ-CNMe2)(μ-H)(CO)2(Cp)2]

Abstract The complexes [Fe2{μ-CN(Me)R}(μ-CO)(NCMe)(CO)(Cp)2]SO3CF3 (R=Me, 2a; 2,6-Me2C6H3, 2b; CH2Ph, 2c), easily obtained from the corresponding [Fe2{μ-CN(Me)R}(μ-CO)(CO)2(Cp)2]SO3CF3 (1a–c) precursors, react with NBu4CN affording the cyano complexes [Fe2{μ-CN(Me)R}(μ-CO)(CN)(CO)(Cp)2] (3a–c) by displacement of the MeCN ligand. The analogous reaction with NBu4Cl leads to the formation of [Fe2{μ-CN(Me)R}(μ-CO)(Cl)(CO)(Cp)2] (4a–b). The μ-hydride complexes [Fe2{μ-CN(Me)R}(μ-H)(CO)2(Cp)2] (5a–b) have been prepared by reaction of 1a–b with NaBH4. The corresponding diruthenium compound [Ru2(μ-CNMe2)(μ-H)(CO)2(Cp)2] (6) has been similarly obtained from [Ru2(μ-CNMe2)(μ-CO)(NCMe)(CO)(Cp)2]SO3CF3. The X-ray molecular structure of 5a is that expected for cis isomers of this family of compounds. It shows a chiral conformation of the C5H5 ligands and the crystals are a conglomerate of enantiomeric individuals. NMR spectra of the various compounds, which are indicative of the presence of α–β or cis–trans isomeric mixtures, are reported and discussed.

Chemistry of di- and tri-metal complexes with bridging carbene or carbyne ligands. Part 15. Reactions of the complex [W(CR)(CO)2(η-C5H5)](R = C6H4Me-4) with iron carbonyls; crystal structures of [Fe2W(µ3-CR)(µ-CO)(CO)8(η-C5H5)] and [FeW2(µ3-RC2R)(CO)5L(η-C5H5)2](L = CO or O)

The compound [W(CR)(CO)2(η-C5H5)](R = C6H4Me-4) in diethyl ether at room temperature reacts with [Fe2(CO)9] to give the dimetal complex [FeW(µ-CR)(CO)6(η-C5H5)](1), and the two trimetal species [Fe2W(µ3-CR)(µ-CO)(CO)8(η-C5H5)](2) and [FeW2(µ3-RC2R)(CO)6(η-C5H5)2](3). Compound (2) with PMe2Ph or Ph2PCH2PPh2(dppm) affords [Fe2W(µ3-CR)(µ-CO)(CO)6L2(η-C5H5)][L = PMe2Ph (4), L2= dppm (5)], complexes in which the phosphine ligands are bonded to the two iron atoms. From the reaction between the complexes [Fe3(CO)12] and [W(CR)(CO)2(η-C5H5)], the trimetal compounds (2), (3), and [FeW2(O)(µ3-RC2R)(CO)5(η-C5H5)2](6) were isolated. Spectroscopic data (infrared and n.m.r.) for the new compounds are reported, and discussed in relation to their structures, which were firmly established for (2), (3), and (6) by single-crystal X-ray diffraction studies. Crystals of (2) are orthorhombic, space group P212121, Z= 4, in a unit cell with lattice parameters a= 10.078(8), b= 13.115(8), and c= 16.785(8)A. The structure was refined to R 0.030 (R′ 0.031) for 5 837 reflections having 2θ⩽ 60°(Mo–KαX-radiation) collected at 200 K. The molecule consists of a Fe2W triangle [Fe–W 2.805(2) and 2.756(2), Fe–Fe 2.538(2)A] capped by a triply bridging tolylidyne ligand [µ3-C–W 2.093(5), µ3-C–Fe 1.969(5) and 2.036(5)A]. The Fe–Fe bond is bridged by a CO group, the remaining carbonyl ligands being terminally bonded, two to the tungsten and three to each iron. Crystals of (3) are triclinic, space group P, Z= 2, in a unit cell with a= 8.622(2), b= 12.799(4), c= 13.443(8)A, α= 90.72(4), β= 108.45(4), and γ= 93.34(2)°. The structure has been refined to R 0.037 (R′ 0.039) for 4 337 reflections having 2θ⩽ 50° collected at room temperature. The molecule consists of a FeW2 triangle, the W–W distance [2.747(1)A] suggesting double bonding. The Fe–W separations [2.731(1) and 2.745(1)] are perceptibly different, and the shorter is transversely bridged by a RC2R alkyne group; one of the carbon atoms of the alkyne triply bridges the metal triangle [µ3-C–W 2.289(5) and 2.264(7), µ3-C–Fe 2.011(5)A]. There are five terminally bound CO ligands, three attached to the iron atom and one to each tungsten. In addition, the tungsten atom σ-bonded to the alkyne carries a CO group which semi-bridges the W–W edge [W–C-0 164.9(7)°]. Crystals of (6) are triclinic, space group P, Z= 2, in a unit cell with a= 8.694(2), b= 12.540(4), c= 13.365(7)A, α= 88.03(4), β= 108.44(3), and γ= 97.54(2)°. The structure has been refined to to R 0.049 (R′ 0.050) for 3 916 reflections having 2θ⩽ 50° collected at room temperature. The molecule has a structure very similar to that of (3) except that an oxygen atom has replaced the terminal CO ligand bonded to the tungsten atom µ-η2 co-ordinated to the alkyne.

Acetonitrile activation in di-iron μ-carbyne complexes: synthesis and structure of the cyanomethyl complex [Fe2(μ-CNMe2)(μ-CO)(CO)(CH2CN)(Cp)2]

Reactions of [Fe 2 {μ-CN(Me)R}(μ-CO)(CO)(NCMe)(Cp) 2 ]SO 3 CF 3 (R=Me, 2a ; CH 2 Ph, 2b ; 2,6-Me 2 C 6 H 3 2c ) with LiBu n afford the corresponding cyanomethyl complexes [Fe 2 {μ-CN(Me)R}(μ-CO)(CO)(CH 2 CN)(Cp) 2 ] ( 3a – c ), presumably via deprotonation and rearrangement of the coordinated acetonitrile. Likewise, the benzylnitrile complex [Fe 2 {μ-CN(Me)(2,6 - Me 2 C 6 H 3 )}(μ-CO)(CO)(NCCH 2 Ph)(Cp) 2 ]SO 3 CF 3 yields [Fe 2 {μ-CN(Me)(2,6 - Me 2 C 6 H 3 )}(μ-CO)(CO)(CH(CN)Ph)(Cp) 2 ] ( 3d ). The X-ray molecular structure of 3a has shown the expected stereogeometry and significant asymmetry of the bridging ligands. Deprotonation and rearrangement of the coordinated MeCN are not observed in the thiocarbyne complex [Fe 2 (μ-CSMe)(μ-CO)(CO)(NCMe)(Cp) 2 ]SO 3 CF 3 ( 5 ) in spite of the similarities with 2a – c . However, compound 5 readily reacts with Li 2 Cu(CN)R 2 (R=Me, Ph) to form the thiocarbene complexes [Fe Sme}(μ-CO)(CO)(Cp) 2 ] ( 6a – b ), with displacement of the acetonitrile ligand.

Isocyanide and heteroallene bridged metal complexes: VII. Further reactions of [Fe(η-C5H5)(CO)2CS2]− with metal compounds☆

Abstract Displacement by [FpCS 2 ] − (Fp = Fe(η-C 5 H 5 )(CO) 2 ) of the halide in EClMe 3 (E = Si, Sn) and Ru(η-C 5 H 5 )(I)(CO) 2 affords the new ferriodithiocarboxylato complexes Me 3 ES(S)CFp ( 2a, 2b ) and (η-C 5 H 5 )(CO) 2 RuS(S)CFp ( 6 ). The latter and its congeners FpC(S)SML n (ML n = Re(CO) 5 , Fp) are alkylated at the thione-S to give the salt-like compounds [FpC(SR)SML n ]CF 3 SO 3 ) (R = Me, Et) ( 7 ) in high yield. FpC(S)SMe acts as a strong S donor ligand towards the neutral metal carbonyl fragments M(CO) 5 (M = Cr, Mo, W) and Mn(η-C 5 H 4 X)(CO) 2 (X = H, Me) but with Co 2 (CO) 8 , only the cluster MeSCCo 3 (CO) 9 ( 14 ) is obtained.

Chemistry of di- and tri-metal complexes with bridging carbene or carbyne ligands. Part 17. Reactions of the compounds [Ru3(CO)12], [Os3(µ-H)2(µ-CH2)(CO)10], and [Os3(CO)10(cyclo-C8H14)2] with [W(CC6H4Me-4)(CO)2(η-C5H5)]; crystal structures of [OsW2{µ3-C2(C6H4Me-4)2}(CO)7(η-C5H5)2](two isomers) and [Os3W(µ3-CC6H4Me-4)(CO)11(η-C5H5)]

Reactions between [W(CR)(CO)2(η-C5H5)](R = C6H4Me-4) and [Os3(µ-H)2(µ-CH2)(CO)10] or [Ru3(CO)12], in tetrahydrofuran and toluene, respectively, afford the cluster compounds [MW2(µ3-RC2R)(CO)7(η-C5H5)2](M = Os or Ru). The molecular structure of the osmiumditungsten compound was established by a single-crystal X-ray diffraction study, which shows that the crystallographic asymmetric unit contains two distinct isomeric molecules (1a) and (1b). In both isomers a OsW2 triangle is µ3-(η2-‖) bridged by the C2(C6H4Me-4)2 ligand but in (1a) the vector joining the ligated carbon atoms of the alkyne lies essentially parallel to the W–W edge [3.159(2)A], whereas in (1b) it lies essentially parallel to an Os–W edge [2.981(2)A]. In both isomers the osmium and tungsten atoms carry three and two CO ligands, respectively, but in (1b) one of these groups is strongly semi-bridging [W–C–O 156(3)°]. The isomers (1a) and (1b) undergo interesting dynamic processes in solution as deduced by variable-temperature 1H n.m.r. studies. The compounds [W(CR)(CO)2(η-C5H5)] and [Os3(CO)10(η2-C8H14)2] react slowly in toluene at room temperature to afford the tetranuclear cluster [Os3W(µ3-CR)(CO)11(η-C5H5)], the structure of which was established by X-ray diffraction. The molecule has an essentially Os3W tetrahedral core, with an Os2W face capped by the tolylidyne ligand. Each osmium carries three terminal CO groups and the tungsten atom is bonded to a η-C5H5 ligand as well as to two CO groups, one of which is semi-bridging [W–C–O 159(2)°]. The Os–Os edge [2.795(1)A] of the capped face is marginally longer than the non-bridged Os-Os edges [2.790(1) and 2.791 (1)A]. In contrast, the Os–W edges [2.874(1) and 2.867(1)A] of the capped face are shorter than the remaining Os–W separation [2.915(1)A]. The µ3-CR ligand is slightly asymmetrically bridging: µ3-C–Os 2.142(14) and 2.048(15), µ3-C–W 2.138(15)A.

Chemistry of thiocarbonyl complexes of the type π-(C5H5)Fe(CO)(CS)(L)+

Abstract Cationic thiocarbonyl complexes of the type π-(C 5 H 5 )Fe(CO)(CS)(L) + have been prepared from π-(C 5 H 5 )Fe(CO) 2 (CS) + and various group V A ligands. The loss of CO in the substitution reaction suggests that the strength of the Fe(CS) bond is greater than that of the Fe(CO) bond. The 13 C n.m.r. spectra of these new thiocarbonyl derivatives indicate that the deshielding of the thiocarbonyl resonance increases as the infrared stretching force constant of the CS group decreases; the shielding of the carbonyl resonance of π-(C 5 H 5 )Fe(CO)(CS)(P(C 6 H 5 ) 3 ) + relative to the π-(C 5 H 5 )Fe(CO) 2 (P(C 6 H 5 ) 3 ) + is attributed to the increased π-acceptor ability of CS relative to CO. The reactions of π-(C 5 H 5 )Fe(CO)(CS)(L) with various nucleophiles such as NH 2 R, CH 3 O − , N 3 − , NH 2 NH 2 have been studied; in all the cases reported the nucleophilic addition occurs, at the carbon of the thiocarbonyl group, in line with the 13 C n.m.r. chemical shift of the thiocarbonyl which indicates a large deshielded carbon resonance. The nucleophilic reactions studied can be summarized as follows: reaction with NH 2 R with formation of π-(C 5 H 5 ) Fe(CO)(L)(CNR) + ; reaction with N 3 − and NH 2 NH 2 leading to π-(C 5 H 5 )Fe(CO)(L)(NCS); reaction with CH 3 O − yielding thiocarbonyl derivatives π-(C 5 H 5 )Fe (CO)(L)(C(S)OCH 3 ).

Synthesis of new heterodinuclear aminocarbyne complexes: crystal structures of [AuW{µ-CN(Et)Me}C6F5)(CO)2(η-C5H5)] and [{CuW{µ-CN(Et)Me}Cl(CO)2(η-C5H5)}2]

The aminocarbyne [W{CN(Et)Me}(CO)2(cp)]1(cp =η-C5H5) reacts with [Au(C6F5)(tht)](tht = tetrahydrothiophene) and CuCl to give the adducts [AuW{µ-CN(Et)Me}(C6F5)(CO)2(cp)]2 and [{CuW{µ-CN(Et)Me}Cl(CO)2(cp)}2]3 respectively which have been structurally characterized by X-ray diffraction. Complex 2 crystallizes in space group P, a= 9.840(5), b= 11.577(6), c= 8.296(6)A, α= 99.03(5), β= 91.01(6), γ= 81.92(4)°, Z= 2. Complex 3 crystallizes in space group P21/a, a= 7.788(2), b= 14.880(5), c= 11.712(5)A, β= 95.35(3)°, Z= 2. Both adducts exhibit a molecule of 1 bonded to Au(C6F5) or Cu2Cl2 fragments, respectively, through one of the W–C(carbyne)π bonds. A WCM ring is formed in which 1 preserves most of its identity and the coinage metals attain their preferred electron counts. The cationic Group 11 fragments [M(PPh3)+](M = Cu, Ag or Au) also react with complex 1 to form [M{W[µ-CN(Et)Me](CO)2(cp)}2]+5; when M = Au NMR spectroscopy indicates that in addition to the trinuclear species 5, the dimetallacyclopropene [AuW{µ-CN(Et)Me}(CO)2(cp)(PPh3]+4 is also present. All these adducts have been spectroscopically characterised.