Derek Sutton

Reactions of rhenium trialkylphosphite complexes (η5-C5Me5)Re(CO)2{P(OR)3} (R Me or Et) with halogens and SbCl5: Reversible Arbuzov-like dealkylation to form rhenium dialkylphosphonate complexes (η5-C5Me5)ReX(CO)2{PO(OR)2}

Abstract The cationic complexes of general formula [(η 5 -C 5 Me 5 )ReX(CO) 2 {P(OR) 3 }] + (R  Me; X  Cl ( 2a ), Br ( 3a ) or I ( 4a )) and (R  Et; X  Cl ( 2b ), Br ( 3b ) an I ( 4b )) have been synthesized by reactions of (η 5 -C 5 Me 5 )Re(CO) 2 {P(OR) 3 } with either halogens X 2 or SbCl 5 . Each is obtained as a mixture of cis and trans isomers of a typical four-legged piano-stool geometry and has been fully characterized in solution by a combination of IR and 1 H, 13 C and 31 P nuclear magnetic resonance spectroscopy. It is observed that under appropriate conditions these cationic complexes undergo transformation to the corresponding neutral dialkylphosphonate complexes of general formula trans -(η 5 -C 5 Me 5 )ReX(CO) 2 {PO(OR) 2 } ( 5a–7a and 5b–7b ) where R  Me ( a ) or Et ( b ) and X  Cl ( 5 ), Br ( 6 ) and I ( 7 ). This is ascribed to a Michaelis—Arbuzov-type dealkylation reaction involving a nucleophilic attack at the alkyl group by the counter-anion, and it is possible to render the cation more (or less) stable to this transformation by suitable choice of the counter-anion and the phosphite. The cationic triethylphosphite complexes exhibit a decreased tendency to undergo the dealkylation reaction. Most interestingly, the product ( i.e. cationic phosphite or neutral dialkylphosphonate) in the reaction of (η 5 -C 5 Me 5 )Re(CO) 5 {P(OR) 3 } with Br 2 at −78°C is dependent on the molar ratio of the reactants; when examined in detail, this is found to result from a counter-ion dependent reversible alkylation-dealkylation process. Thus the dialkylphosphonate is unchanged by treatment with alkylbromide alone but is completely transformed back to the cationic trialkylphosphite complex by alkyl bromide and bromine .

Aryldiazenido, aryldiazene, and arylhydrazido complexes. Further studies of ortho-metalated iridium complexes derived from reactions of aryldiazonium ions with IrH(CO)(PPh3)3 and IrH(CO)2(PPh3)2

Abstract The syntheses are described of ortho-metalated iridium arylhydrazido complexes [Ir(NHNHC6H3X)(CO)(PPh3)2]BF4, where X = H, 4-F, 3-F, 2-F, 4-OMe, 2-OMe, 2-NO2, 3-NO2, 3-CH3, 4-CH3 and 2-CF3 from the reactions of the corresponding arenediazonium tetrafluoroborates with IrH(CO)(PPh3)3 or IrH(CO)2(PPh3)2. A high-yield synthesis of the 2-NO2 complex from the diazonium salt and IrCl(CO)(PPh3)2 is also reported, and this complex has been the subject of a multinuclear (1H, 13C, 31P, 15N) NMR study. Oxidation of these arylhydrazido complexes to ortho-metalated aryldiazene complexes [Ir(NH NC6H3X)(Y)(CO)(PPh3)2]BF4, where Y = F, FBF3, Cl, Br or I occurs with air and halogens.

Structures of cationic di-iridium complexes derived from (η5-C5Me5)Ir(CO)2, including the dication [(η5-C5Me5)(CO)2Ir–Ir(CO)2(η5-C5Me5)]2+ and the bridging methylenetetramethylcyclopentadienyl (tetramethylfulvene) complex [(η5-C5Me5)(CO)Ir–Ir;(CO)2(η5-CH2C5Me4)]+

(η5-C5Me5)Ir(CO)2(1) reacts with Ph3C+ to give the dinuclear dication [(η5-C5Me5)(CO)2Ir–Ir(CO)2(η5-C5Me5)]2+(4) and with (η5-C5Me5)Ir(CO)Cl2 in presence of one equivalent of Ag+ to give [(η5- C5Me5)(CO)(Cl)Ir–Ir(CO)2(η5-C5Me5)]+(2); both (2) and (4) may be converted to the complex [(η5-C5Me5)(CO)[graphic omitted]H2C5Me4)]+(3) containing a rare bridging methylenetetramethylcyclopentadienyl (tetramethylfulvene) ligand.

Cationic Aryltetrazene Complexes of Iridium

The details of the synthesis and properties of a number of cationic iridium aryltetrazene complexes of general formula [Ir(CO){N4(C6H4R)2}(PPh3)2]+ where R = H or para-F, Cl, Br, CF3, or OCH3 are presented. The complexes are compared with a number of other compounds possessing tetrazene or tetraazadiene ligands. A possible mechanism of formation is presented, consistent with presently available evidence.

Characterization of 1:1 heterobimetallic complexes of (η5-C5Me5)Ir(CO)2 with zinc, cadmium and mercury(II) chloride and the X-ray structure determination of the 1:2 mercury complex

Abstract (η 5 -C 5 Me 5 )Ir(CO) 2 reacts with ZnCl 2 , CdCl 2 or HgCl 2 , to produce the heterobimetallic complexes (η 5 -C 5 Me 5 )(CO) 2 IrMCl 2 (M  Zn ( 1 ), Cd ( 2 ), Hg ( 3a )) and [(η 5 -C 5 Me 5 )(CO) 2 IrHgCl][HgCl 3 ] ( 3b ). The X-ray crystal structure of 3b shows that the iridium atom adopts a three-legged piano stool coordination geometry, with two terminal CO ligands and an unbridged nearly linear, IrHgCl group (IrHg(1) = 2.587(1) A and IrHg(1)-Cl(1) = 172.1(2)°). The [HgCl 3 ] - anion is linked by Hg(2) to the Cl(1) atom of the cation (Hg(2) … Cl(1) 2.914(6) A) and through Cl(3) to the Hg(1) atom of a neighboring symmetry-related cation with Hg(1) … Cl(3) 3.011(5) A.

Cationic rhenium allyl complex [Cp∗Re(η3-C3H5)(CO)2][BF4] and its acetonitrile derivatives [Cp∗Re(η3-C3H5)(CO)(NCMe)][BF4] and [Cp∗Re(η3-C3H5)(NCMe)2][BF4]. Products of reactions with borohydride, methoxide and trimethylphosphine, and the X-ray crystal structure of the bis-ethylamine complex [endo-Cp∗Re(η3-C3H5)(NH2Et)2]ReO4].solv

Abstract By replacing one or both of the CO groups in [ Cp ∗ Re (η 3 - C 3 H 5 )( CO ) 2 ][ BF 4 ] (1) by MeCN to give [ Cp ∗ Re (η 3 - C 3 H 5 )( CO )( NCMe )][ BF 4 ] (3) or [ Cp ∗ Re (η 3 - C 3 H 5 )( NCMe ) 2 ][ BF 4 ] (4), it was anticipated that the MeCN groups would be labile and would promote ligand substitutior reactions, leading to a variety of new rhenium η3-allyl half-sandwich derivatives. Instead, MeCN is found to be difficult to substitute, and nucleophiles often result in products that arise from attack at either the MeCN or allyl ligands. Complex 1 reacted with NaBH4 to give the propene complex Cp ∗ Re (η 3 - CH 2 CHCH 3 )( CO ) 2 (2), with NaOMe to give the methoxycarbonyl complex Cp ∗ (η 3 - C 3 H 5 )( CO )( COOMe ) (6) and the 3-methoxypropene complex Cp ∗ Re (η 2 - CH 2 CHCH 2 OMe )( CO ) 2 (5), and with PMe3 to give [ Cp ∗ Re (η 2 - CH 2 CHCH 2 PMe 3 )( CO ) 2 ][ BF 4 ] (7). Complex 3 gave the ethylamine complex [ Cp ∗ C 3 H 5 ( CO )( NH 2 Et )][ BF 4 ] (8) when reacted with NaBH4, [ Cp ∗ Re (η 2 - CH 2 CHCH 2 PMe 3 )( CO )( NCMe )][ BF 4 ] (9) with PMe3, and Cp ∗ Re (η- 3 - C 3 H 5 )( CO )( NHCOMe ) (10) with NaOH. Complex 4 similarly yielded the bis-ethylamine complex [ Cp ∗ Re (η 3 - C 3 H 5 )( NH 2 Et ) in2 ][ BF 4 ] (11) when reacted with NaBH4, but with PMe3 ligand substitution occurred, resulting in [ Cp ∗ Re (η 3 - C 3 H 5 )( NCMe )( PMe 3 )][ BF 4 (12). Treating 12 with NaBH4, or 11 wiht PMe3, yielded the ethylamine complex [ Cp ∗ Re (η 3 - C 3 H 5 )( PMe 3 )( NH 2 Et )][ BF 4 ] (13). The X-ray crystal structure of [endo- Cp ∗ Re (η 3 - C 3 H 5 )( NH 2 Et ) 2 ][ ReO 4 ]. solv has been determined. This compound crystallizes in the space group Pnma with a = 8.6554(8) A , b = 11.729(2) A , c = 26.928(3) A , V = 2733.7 A 3 , and Z = 4 . The structure was refined to RF = 0.028 for 1444 data (I0 ⩾ 2.5 σ(I0), 2θmax = 46°) and 158 variables. The cation has a crystallographic mirror plane that relates the two EtNH2 ligands and bisects the endo-η3-allyl and Cp∗ ligands. Selected distances and angles are ReN = 2.228(7) A , ReC (6) = 2.177(9) A (allyl terminal carbon), ReC (7) = 2.090(13) A (allyl central carbon), NC (4) = 1.470(10) A , ReNC (4) = 125.2(6) A , and C (6)- C (7)- C (6) = 114.1(13) A

Synthesis, structure and dynamics of endo- and exo-isomers of η3-allyl(η5-pentamethylcyclopentadienyl)dicarbonylrhenium tetrafluoroborate, [(η5-C5Me5)Re(CO)2(η3-C3H5)][BF4]

Abstract The cationic η 3 -allyl complex [Cp ★ Re(CO) 2 (η 3 -C 3 H 5 )][BF 4 ] ( 1 ) has been synthesized from the propene complex Cp ★ Re(CO) 2 (η 2 -C 3 H 6 ) ( 2 ) by reaction with [Ph 3 C][BF 4 ]. The 1 H NMR spectrum of 1 in CD 2 Cl 2 exhibits individual sets of methyl and allyl resonances corresponding to endo and exo isomers in an approximate ratio endo:exo = 6.4:1. The resonances that are identified with each isomer were determined by application of the nuclear Overhauser effect. Magnetization transfer results show that endo—exo interconversion occurs with no scrambling of syn and anti protons, consistent with a pseudorotation mechanism but not a η 3 -η 1 -η 3 mechanism. The crystal structure of 1 has been determined. The analysis gave a model in which both endo and exo isomers are present in an approximate ratio endo:exo = 4:6. Crystals of 1 are orthorhombic, space group Pcab with a = 12.3142(12), b = 12.8148(18), c = 21.767(3) A, V = 3434.9 A 3 , Z = 8. The structure was refined to R F = 0.027 and R WF = 0.038 using 1480 observed intensities in the range 4 l = 2 n ); 4 l = 2 n + 1) collected on an Enraf Nonius CAD-4F diffractometer with graphite monochromatized Mo- K α radiation.

‘Side-on’ co-ordination of a phenylhydrazido ligand: synthesis and X-ray structure determination of [(η5-C5H5)2W(H2NNPh)][BF4]

The low-temperature product, [(η5-C5H5)2WH(NNHR)][X](R = aryl, X = BF4 or PF6), from the reaction of [RN2][X] with (η5-C5H5)2WH2 rearranges in solution above –20 °C to yield [(η5-C5H5)2W(H2NNR)][X] in which the arylhydrazido ligand is bound to W in a ‘side-on’ or dihapto manner.

Synthesis and X-ray structures of mono- and bis-acetonitrile derivatives of the cationic rhenium allyl complex [η5-C5Me5) Re(CO)2(η3-C3H5)][BF4]

Abstract Replacement of CO ligands in the η 3 -allyl complex [Cp*Re(CO) 2 (η − C 3 H 5 )][BF 4 ] 1 has been accomplished by reacting 1 in acetonitrile with PhIO or Me 3 NO to yield endo isomers of [Cp*Re(CO)(NCMe)(η 3 -C 3 H 5 )][BF 4 ] 2 and [Cp*Re(NCMe) 2 (η 3 -C 3 H 5 )][BF 4 ] 3 respectively. The assignment of the allyl proton resonances and the isomeric forms of 2 and 3 have been deduced with the aid of 1 H nuclear magnetic resonance nuclear Overhauser enhancement experiments. The X-ray crystal structures of 2 and 3 confirm that these are endo isomers. Poor quality crystals of 2 (with 0.5 toluene solvate) are monoclinic, of space group P 2 1 / c , with Z = 4, a = 8.381(2) A, b = 15.389(2) A c = 17.161(3) A, β = 91.71(2)° and V = 2212.4 A 3 . The structure refined to R F = 0.060 for 1950 data ( I o ⩾ 2.5σ(I o )). Crystals of 3 are orthorhombic, of space group P 2 1 2 1 2 1 , with Z = 4, a = 11.296(2) A, b = 12.012(2) A, c = 14.760(2) A and V = 2002.7 A 3 . The structure refined to R F = 0.027 for 1815 data ( I o >/ 2.5σ( I o )). The rhenium atom is bonded to the allyl group in 3 with an ReC(7) distance of 2.124(11) A to the central carbon atom and an ReC(6) distance of 2.177(12) A and an Re-C(8) distance of 2.201(12) A to the terminal carbon atoms. The acetonitrile groups are bound with an ReN(1) distance of 2.089(7) A and an ReN(2) distance of 2.086(10) A, and NC with an N(1)C(9) distance of 1.125(11) A and an N(2)C(11) distance of 1.134(14) A.

Synthesis of heterotrimetallic (Fe–Co–Ni)–acetylene clusters and X-ray crystal structure of (η5-C5H5) NiCoFe(CO)5(PPh3)(C2Ph2)

The heterobimetallic complexes (η5-C5H5) NiCo(CO)3(C2R1R2)[R1= Ph; R2= Ph or Me] react with Fe2(CO)9 to yield the heterotrimetallic clusters (η5-C5H5) NiCoFe(CO)6(C2R1R2); the stereochemistry of a triphenylphosphine derivative, the title compound, has been established by a single-crystal X-ray structure analysis.