Giacomo Facchin

Functionalized ylides: new trends in organometallic chemistry

The coordination and organometallic chemistry of P- and As-carbonyl stabilized ylides is reviewed. As a general feature, the coordination chemistry of R3ECHCOR′-type (E=P, As) ligands appears to be dominated by C(ylide) metal coordination, although a few examples of O(ylide)-bound complexes are known. The factors addressing C(ylide)-vs. O(ylide)-coordination in Pt(II) and Pd(II) systems are examined. The Ni(II) complexes containing P,O-chelate ylide ligands are also discussed, with a special emphasis on their catalytic activity. The synthesis and reactivity of phosphonium functionalized isocyanides and their corresponding ylides, which provide a new route to metal coordinated indole systems, are described. Finally, the reactivity of Ph3PCCO towards metal substrates is summarized including the formation of ketenyl complexes.

Functionalized isocyanides as ligands. Synthesis of 2-(chloromethyl)- and 2-(iodomethyl)phenyl isocyanides and their transition-metal complexes

Preparation de 2-(XCH 2 ) C 6 H 4 NC (X=Cl ou I) par reaction en 4 etapes. Synthese des complexes de Pd, Pt, Cr, W et Do

Synthesis and characterization of palladium(II)-η3-allyl–ylide complexes. X-Ray crystal structure of [PdCl(η3-2-MeC3H4){Ph3PC(H)COMe}]

The complexes [PdCl(η3-2-XC3H4){Ph3PC(H)COR}][R = Me, X = H (1) or Me(2); R = Ph, X = H (3) or Me (4)] have been obtained in high yields by treatment of the dimers [{PdCl(η3-2-XC3H4)}2] with the keto-stabilized ylides Ph3PC(H)COMe [ampp, (acetylmethylene)triphenylphosphorane] and Ph3PC(H)COPh [bmpp, (benzoylmethylene)triphenylphosphorane] in CH2Cl2 solution. They have been characterized by analytical data, i.r., low-temperature 1H and 31P-{1H} n.m.r., and for complex (2) also by 13C n.m.r. spectroscopy. Spectroscopic evidence indicates that complexes (1)–(4) in solution at low temperature are present as two diastereoisomeric forms arising from co-ordination on the metal centre of the asymmetric ylidic carbon atom and of the η3-allyl ligand. In CH2Cl2 solution at room temperature the complexes are in equilibrium with their reagents. Reaction with PPh3 and [AsPh4]Cl gives [ PdCl(η3-2-XC3H4)(PPh3)] and [AsPh4][PdCl2-(η3-2-XC3H4)], respectively, and the free ylide. The X-ray crystal structure of complex (2) was determined showing that, in the solid state, only one diastereoisomer is present. The crystals are monoclinic, space group P21/n with a= 9.668(3), b= 14.879(4), c= 16.226(3)A, β= 99.85(2)°, and Z= 4. Final full-matrix least-squares refinement, based on 3 063 reflections, converged to R= 0.031. The keto-stabilized ylide ligand is C bonded to the metal with a Pd–C distance of 2.193(3)A.

Influence of ancillary ligands in the coordination mode of P and As carbonyl stabilized ylides on Pt(II) systems. X-ray structure of trans-[Pt(PPh3)2(CF3) {OC(OCH3)C(H) (PPh3)}] [BF4]·0.5CH2Cl2

Abstract The carbonyl stabilized P and As Ph3PHCOR (RCH3, Ph, OCH3) and Ph3ASCHCOR (RCH3, PH, OCH3) have been reacted with some platinum(II) complexes bearing ancillary ligands with different steric hindrance, in order to determine the factors that influence the C- versus O-coordination mode of the ylides. Thus, the reactions of [(dppe)PtCl2] and [(dppv)PtCl2] with Ph3PCHCOR (R^z.dbnd;CH3, Ph) give the O-coordinated complexes, while with Ph3PCHCOOCH3 they give the corresponding C-coordinated derivatives. The reactions of trans-[PPh3)2(CF3)Pt(solv)]+BF−4 yieldd the O-coordinated compounds and the reactions with [Pt(C3H5)Cl]4 give selectivity the C-coordinated derivatives as well as the reactions with the dimer [ PlCl(P(Bu 2 ) 2 C(Me) 2 C H 2 }] 2 . The derivative trans-[Pt(PPh3)2(CF3){OC(OCH3)=C(H)(PPh3)}][BF4]] crystallizes in the triclinic group P1 (No. 2), a = 10.385(4), b = 14.844(5), c = 18.511(6) →A , α = 96.46(2), β=99.79(2), γ = 97.00(2)°, V = 2765(1) a A 3 , Z = 2 . The values of coordination distances and of the PtOC angle appear influenced by steric factors.

Poly(organophosphazene)s and the sol–gel technique

We report a survey of the utilization of phosphazene materials in combination with metal alkoxide precursors to form ceramics through the sol‐gel technique. Silicon, titanium, zirconium and aluminum three-dimensional oxide networks were exploited for these investigations, while variably functionalized poly[bis (2,2,2-trifluoroethoxy)phosphazene], poly[bis (methoxyethoxyethoxy)phosphazene] and poly [bis(4-hydroxyphenoxy)phosphazene] were used as phosphazene substrates. The resulting new hybrid materials, characterized by SEM, EDAX, DTA, TGA, DSC, DMTA and impedance techniques, showed improved thermal and mechanical stability, and higher ionic conductivity when doped with Li a or Ag a triflates, than those ob

Organometallic and coordination chemistry on phosphazenes Part I. Zn(II), Pd(II) and Pt(II) complexes on Schiff base-containing cyclophosphazenes

Abstract In this paper we report the synthesis of a new class of cyclophosphazene ligands containing six Schiff bases in the side branches, able to bind transition metals. We describe also the complexation reaction on these substrates of Zn(II), Pd(II) and Pt(II) ions. Elemental analyses together with spectroscopic (IR, UV, 1 H and 31 P NMR) and mass spectrometric (FAB) characterizations reveal that all the above mentioned cyclophosphazenes are able to coordinate six metal ions.

Synthesis, coordination and reactivity of 2-(trimethylsiloxymethyl)phenyl- and 2-(hydroxymethyl)phenyl isocyanides

Abstract 2-(Trimethylsiloxymethyl)phenyl isocyanide, 2-(CH 2 OSiMe 3 )C 6 H 4 NC ( 2 ) was prepared by reaction of 2-(trimethylsiloxymethyl)phenyl formamide, 2-(CH 2 OSiMe 3 )C 6 H 4 NHCHO ( 1 ) with trichloromethyl chloroformate. Reaction of 2 with F − ions in MeOH leads to the formation of 2-(hydroxymethyl)phenyl isocyanide, 2-(CH 2 OH)C 6 H 4 NC ( 3 ), which is stable as free ligand and does not spontaneously undergo intramolecular cyclization to 4H-benzo[1,3]oxazine. The isocyanide 2 coordinates to Pt(II) and Pd(II) metal ions such as in the complexes cis -[MCl 2 (CNC 6 H 4 2-CH 2 OSiMe 3 ) 2 ] and cis -[PdCl 2 (CNC 6 H 4 -2-CH 2 OSiMe 3 )(PPh 3 )], which are converted to the corresponding benzoxazin-2-ylidene derivatives [ MCl 2 ( CN ( H ) C 6 H 4 2- CH 2 O ) 2 ] and [ PdCl 2 ( CN ( H ) C 6 H 4 2- CH 2 O )( PPh 3 )] , respectively, in the presence of a catalytic amount of F − ions in MeOH. On the other hand, coordination of 2 to the {M(CO) 5 } (M=W, Cr) fragments and subsequent reactions with of F − ions in MeOH affords the corresponding 2-(hydroxymethyl)phenyl isocyanide complexes [M(CO) 5 (CNC 6 H 4 2-CH 2 OH)], where the hydroxy function does not react with the coordinated isocyanide group.

Preparation and characterization of PdIII-ylide complexes of type Pd(CNR)(η3-2-XC3H4)[Ph3PC(H)COMe] BF4 (X = H, Me; R = p-C6H4OMe, C(Me)3, Me, C6H11, p-C6H4NO2). Crystal structure of Pd[CNC(Me)3]-(η3-2-MeC3H4)[Ph3PC(H)COMe] BF4

Seven compounds of general formula Pd(CNR)(η3-2-XC3H4)[PH3PC(H)COMe]BF4(X = H, R = p-C6H4OMe (1, R = C(Me)3 (2; X = Me, R = p-C6H4OMe (3), C(Me)3 (4), Me (5), C6H11 (6), p-C6H4NO2 (7)) have been prepared by chloride abstraction from PdCl(η3-2-XC3H4)[Ph3PC(H)COMe] (X = H, me) with AgBF4 and subsequent reaction of the cationic intermediate with the appropriate isocyanide ligand. all the complexes have been characterized by analytical and spectroscopic (IR, 1H and 31P1H NMR) data. They have been shown to be a mixture of two diastereoisomeric forms arising from the simultaneous presence on the palladium atom of the asymmetric ylidic carbon atom and the η3-allyl ligand. The determination of the crystal structure of complex 4 showed that in the solid state only one diastereoisomer is present. The crystals are monoclinic, space group Pc with a 9.833(3), b 14.383(4), c 11.762(4) A, β 114.68(3)°, and Z = 2. Final full-matrix least-squares refinement, based on 2413 reflections, converged to R = 0.050. The keto-stabilized ylide ligand is C bonded to the metal with a PdC distance of 2.175 (9) A.

Reactivity of carbonyl stabilized ylides with Zeise's salt. Synthesis, characterization of mono- and bis-ylidic Pt(II) derivatives and X-ray crystal structure of the {PtCl2[C(H)COCH3(PPh2-o-C6H4)[PPh3CH2COCH3] complex

Abstract Phosphorus and arsenic keto-stabilized ylides (APPY, CMPPY, BPPY, BCyPY-OMe, APAsY, CMPAsY, BPAsY) react with Zeises salt to give the corresponding monosubstituted Pt(II) complexes trans-[PtCl2(η2-C2H4) (ylide)] (1–7). The bis-ylide complexes trans-[PtCl2(ylide)2] (8–12) and trans-[PtCl2(ylide)(ylide′)] (13–17) can bbe prepared by reaction of 1–7 with the corresponding ylides. Upon heating complex 8 trans-{PtCl2[C(H) (PPh3) COCH3]2} in THF a cyclization reaction occurred to give {PtCl2[C(H)COCH3(PPh2-o-C6H4)]}[Ph3PCH2COCH3] (18). The molecular structure of compound 18 was determined by X-ray diffraction. The molecule consists of a metallic anion and a phosphonium counterion. Compound 18 crystallizes in the monoclinic space group P21/c with unit cell parameters a = 13.855(3), b = 14.242(3), c = 20.173(4) A , β = 109.31(5)°, Z = 4 .

New materials based on the reaction of cyclo- and poly-(organo phosphazenes) with SiO2, TiO2 and ZrO2 precursors

A new class of organic-inorganic materials can be prepared, based on inorganic networks and cycloor poly-(organophosphazenes). Poly(organophosphazenes) are polymers characterized by many interesting technological properties. This report is based on a investigation on the reactivity of SiO2, TiO2 and ZrO2 precursors with different phosphazene compounds functionalized with hydroxyl groups, to prepare materials with a hybrid structure. The synthesis of these systems was studied in different experimental conditions. Evidences on the structures and properties of these materials will be presented on the basis of FTIR, SEM and thermal analysis characterization results.