Lesley J. S. Sherry

Chemistry of metallacyclobutanones. Part 2. Synthesis and ring inversion of some highly puckered metallacyclobutan-3-one (slipped oxodimethylenemethane) complexes of palladium; crystal structures of 2,4-bis(methoxycarbonyl)-1,1-bis(triphenylphosphine)palladacyclobutan-3-one, 2,4-bis(methoxycarbonyl)-1,1-bis(triphenylarsine)palladacyclobutan-3-one, and 1,1-(2′,2″-bipyridyl)-2,4-bis(methoxycarbonyl)palladacyclobutan-3-one

The reactions of the zerovalent palladium complex [Pd2(dba)3]·CHCl3(dba = dibenzylidene-acetone, PhCHCH–C(O)–CHCHPh), in the presence of a donor ligand L and dioxygen, with esters of 3-oxopentanedioic acid (RCH2COCH2R) in diethyl ether, afford, in high yield, the pallada-cyclobutan-3-one compounds [P[graphic omitted]HR)L2][R = CO2Me, L = PPh3, PMePh2, PMe2Ph, PEt3, or AsPh3, L2= 2,2′-bipyridyl (bipy); R = CO2Et, L = PPh3 or AsPh3, L2= bipy; R = CO2Prn, L2= bipy]. The compounds [P[graphic omitted]HR)L2](R = CO2Me or CO2Et, L = PPh3 or AsPh3) are also formed upon treatment of benzene solutions of [PdL4] with RCH2COCH2R in the presence of air. Treatment of the ketone MeO2CCH2COCH2CO2Me with either [Pd(O2)(PPh3)2] in benzene or [Pd(OCO3)(PPh3)2] in ethanol also affords [P[graphic omitted]H(CO2Me)}(PPh3)2]. Spectroscopic data (i.r. and n.m.r.) for the new compounds are reported, and discussed in relation to their structures, which were firmly established for [P[graphic omitted]H (CO2Me)}L2]·H2O [L = PPh3(3a), L = AsPh3(3e), and L2= bipy (3f)] by single-crystal X-ray diffraction studies. Crystals of (3a) are triclinic, space group P, Z= 2, in a unit cell with lattice parameters a= 11.995(5), b= 17.72(1), c= 10.30(1)A, α= 94.7(1), β= 110.8(1), and γ= 102.84(2)°. The structure was refined to R 0.055 (R′ 0.060) for 5 093 reflections having 7 ⩽ 2θ⩽ 54°(Mo-KαX-radiation) collected at room temperature. Crystals of (3e) are triclinic, space group P, Z= 2, in a unit cell with lattice parameters a= 12.219(6), b= 17.56(1), c= 10.44(1)A, α= 93.3(1), β= 110.8(1), and γ= 103.56(2)°. The structure was refined to R 0.043 (R′ 0.046) for 6 025 reflections having 7 ⩽ 2θ⩽ 54° collected at room temperature. Crystals of (3f) are monoclinic, space group P21/c, Z= 4, in a unit cell with lattice parameters a= 8.43(1), b= 14.594(6), c= 14.170(6)A and β= 92.1(1)°. The structure was refined to R 0.043 (R′ 0.032) for 4 000 reflections having 7 ⩽ 2θ⩽ 60° collected at room temperature. The three molecules contain a highly puckered palladacyclobutan-3-one ring [fold angles 53.3(2) for (3a), 52.3(4) for (3e), and 51.3(3)° for (3f)] with a weak transannular Pd–C bond [Pd–C(2) 2.389(7) for (3a), 2.384(6) for (3e), and 2.374(3)A for (3f)]. The molecules can be alternatively formulated with slipped η3-oxodimethylenemethane ligands. Variable-temperature 1H n.m.r. data for the compounds [P[graphic omitted]HR)L2](R = CO2Me, L = PPh3, PMePh2, PMe2Ph, PEt3, or AsPh3; L2= bipy) are interpreted in terms of inversion of the palladacyclobutan-3-one ring through a planar transition state.

Mononuclear η3-allylosmium hydride complexes and the X-ray crystal structure of the solvento complex [OsH(H2O)(CO)2(PPh3)2]BF4•EtOH

Abstract The osmium(II) hydride [OsHCl(CO)(PPh3)3] reacts with 2-methylallylmagnesium chloride and allylmagnesium chloride to give the air-stable η3-allylosmium hydride complexes [OsH(CO)(η3-CH2CRCH2)(PPh3)2] (R = Me or H). The orientation of the η3-allyl ligand in these complexes has been established by NOE difference spectra. Treatment of [OsH(CO)(η3-CH2CMeCH2)(PPh3)2] with fluoroboric acid in the presence of a ligand L (L = Ph3P or CO) affords the cationic hydride complexes [OsH(CO)(OH2)(L)(PPh3)2][BF4]. The crystal structure of [OsH(CO)2(OH2)(PPh3)2][BF4] · EtOH has been determined.

Trimethylenemethane complexes of osmium and iridium; crystal structure of η4-trimethylenemethanechlorocarbonyltriphenylphosphineiridium

The η4-trimethylenemethane complexes [Os{η4C(CH2)3}(CO)2(PPh3)], [Ir{η4-C(CH2)3}(Cl)(CO)(PPh3)], and [Ir{η4-C(CH2)3}(CO)(PPh3)2][PF6] have been prepared by treating [Os(CO)2(PPh3)3] with Me3SiCH2C(CH2)CH2OAc, trans-[IrCl(CO)(PPh3)2] with Me3SiCH2C(CH2)CH2Cl, and trans-[IrCl(CO)(PPh3)2] plus KPF6 with Me3SiCH2C(CH2)CH2Cl, respectively; the X-ray crystal structure of [Ir{η4-C(CH2)3}(Cl)(CO)(PPh3)] indicates that the trimethylenemethane is not symmetrically bound to the iridium.

New syntheses of metallacyclobutan-3-one (slipped oxodimethylenemethane) complexes of platinum (II) and the X-ray crystal structure of 2,4-diacetyl-1,1-bis(triphenylphosphine) platinacyclobutan-3-one; CH bond orientation and the magnitude of 2J(PtH)

Abstract Treatment of the carbonate complexes [Pt(CO3)L2] (L = PPh3, PMePh2, PMe2Ph, or AsPh3; L2 = Ph2PCH2CH2PPh2) with esters of 3-oxoglutaric acid RCH2COCH2R (R = CO2Me, CO2Et, or CO2Prn) and with heptane-2,4,6-trione afford platinacyclobutan-3-one complexes, 1H NMR studies indicating that the magnitudes of 2J(PtH) and 3J(PH) are dependant upon the orientation of the coupled hydrogen to the square planar metal function; the structure of [P t{CH(COMe)COC H(COMe)}(PPh3)2] has been established by X-ray diffraction.

Synthesis and reactivity of aminomethyldiphenylphosphine complexes of molybdenum. Crystal structure of cis-[Mo(CO)4(Ph2PCH2NHC6H4Me-p)2]

Abstract The phosphines Ph 2 PCH 2 NHR (R = Bu t , C 6 H 4 Me-4) react with [Mo(CO) 4 (norbornadiene)] or [Mo(CO) 4 (piperidine) 2 ] to form cis -[Mo(CO) 4 (Ph 2 PCH 2 NHR) 2 ]. The crystal structure has been determined for R = C 6 H 4 Me-4. Reaction of these complexes with aqueous formaldehyde gives the complexes [Mo(CO) 4 }(Ph 2 PCH 2 ) 2 -NR}] which were also prepared independently from (Ph 2 PCH 2 ) 2 NR.

Oxidation of 2,4-dinitrobenzenesulphenamide in the presence of 2,3,4,5-tetraphenylpyrrole.

Oxidation of the title sulphenamide (1) with lead tetra-acetate in the presence of 2,3,4,5-tetraphenylpyrrole gave 2,4,5,6-tetraphenylpyrimidine (3) and 2-(2,4-dinitrophenylthioamino)-2,3,4,5-tetraphenyl-2H-pyrrole (7) as major products. The structure of (7) has been confirmed by X-ray crystallography.

Chemistry of metallacyclobutanones. Part 3. Reactions of heptane-2,4,6-trione and 1,5-diphenylpentane-1,3,5-trione with some carbonate complexes of platinum(II); X-ray crystal structures of [Pt{CH(COMe)COCH(COMe)}(PPh3)2] and [Pt{OC(CHCOPh)CHC(Ph)O}(PPh3)2]

Heptane-2,4,6-trione reacts with the carbonate complexes [Pt(CO3)L2] in warm ethanol to afford high yields of the piatinacyclobutan-3-one complexes [P[graphic omitted]HR)L2](R = COMe, L = PPh3 or AsPh3). A single-crystal X-ray diffraction study has been carried out on the complex [[graphic omitted]H(COMe)}(PPh3)2]. The molecular structure can be considered to be based upon a highly puckered platinacyclobutan-3-one ring complex [fold angle 48.0(4)°] with a weak transannular Pt–C bond of 2.486(6)A, the allylic structure [Pt{η3–CH(COMe)COCH(COMe)}(PPh3)2] making a significant contribution to the bonding. N.m.r. data (1H, 13C-{1H}) are reported and variable-temperature 1H n.m.r. data for the complexes [P[graphic omitted]H(COMe)}L2](L = PPh3 or AsPh3) are interpreted in terms of inversion of the platinacyclobutan-3-one ring through a planar transition state. In contrast, 1,5-diphenylpentane-1,3,5-trione reacts with [Pt(CO3)(PPh3)2] in warm ethanol to afford the dienediolate complex [[graphic omitted]}(PPh3)2] which was characterised by X-ray crystallography.

Intramolecular trapping of N-nitrenes: trapping by a remote 2,4-dimethoxyphenyl ring

From oxidation of the N-aminoquinazolone (2) in methanol, three crystalline products (4), (5), and (6) have been isolated and the structures of two of them confirmed by X-ray crystallography; oxidation of (2) in benzene yields the meta-bridged N-nitrene ‘insertion’ product (3) in 60% yield.

A stereocontrolled synthesis and X-ray crystal structure of a 2,3,3-trisubstituted cyclohexanone

A γ,δ-unsaturated amide, prepared by an amide acetal Claisen rearrangement, has been subjected to hydroxy-lactonisation, and reductive cleavage of the corresponding keto-lactone with aluminium amalgam has led to a trisubstituted cyclohexanone derivative with retention of configuration, thus establishing a new method for the stereocontrolled synthesis of 2,3,3-trisubstituted cyclohexanones.

Intramolecular trapping of N-nitrenes: oxidation products of 3-amino-2-(2,4-dimethoxyphenylpropyl)quinazolin-4(3H)-one

Oxidation of the title N-aminoquinazolone (2) with lead tetra-acetate in methanol gave the bridged structure (4) which, when left in methanol, was converted into (5) whose cyclopentane ring-containing structure was confirmed by X-ray crystallography.