Wengan Wu

Reactions of the dirhenium(II) complexes Re2X4(dppm)2 (X = Cl, Br; dppm = Ph2PCH2PPh2) with isocyanides VI. Further studies on isomers of the edge-sharing bioctahedral species [Re2C13(μ-dppm)2(CO)(CNxyl)2]+☆

Abstract The different types of structural isomerism that exist for those dirhenium(II) halide complexes which contain bidentate phosphines of the type R 2 P(CH 2 )PR 2 ( n = 1 or 2) are examined. A particular focus of this report are those complexes which are formed from the reactions of Re 2 X 4 (μ-dppm) 2 (X = Cl or Br; dppm = Ph 2 PCH 2 PPh 2 ) with CO, RNC or RCN ligands; up to three of these ligands can be coordinated either alone or in combination with one another. The earlier literature is reviewed and new examples of edge-sharing bioctahedral complexes which exist in different isomeric forms are reported. Yellow and green isomers of the salts [Re 2 Cl 3 (μ-dppm) 2 (CO)(CNxyl) 2 ]Y (Y = Cl, ReO 4 , S0 3 CF 3 or PF 6 ) have been isolated by the reactions of Re 2 C1 4 (μ-dppm) 2 (CO) and Re 2 C1 4 (μ-dppm) 2 (CO)(CNxyl) with xylNC in the presence of Tl + . Both forms contain bridging carbonyl ligands; the yellow form undergoes thermal isomerization to the symmetrical all- cis green isomer when its solutions in 1,2-dichloroethane are refluxed. The structure of the green isomer of composition [Re 2 C1 3 (u-dppm) 2 (CO)(CNxyl) 2 ](ReO 4 ) 0.82 Cl 0.18 ( IIb ) has been determined by single crystal X-ray crystallography. Crystal data for IIb at 293 K: orthorhombic space group Pnma (No. 62), a = 29.872(7)A, b = 21.948(3)A, c = 10.944(1)A, V = 7175(3)A 3 , Z = 4. The structure was refined in full-matrix least squares to R = 0.056 (R w = 0.072) for 2894 data with I > 3 σ ( I ). The Re-Re bond length of 2.576(1) A is characteristic of edge-sharing bioctahedral species that are derived from the non-redox reactions of Re 2 X 4 (μ-dppm) 2 with neutral donors.

Reactions of the dirhenium(II) complexes Re2X4(μ-dppm)2 (X=Cl, Br; dppm=Ph2PCH2PPh2) with isocyanides. Part XVII. Isomerizations of triply bonded dirhenium complexes of the type [Re2X3(μ-dppm)2(CO)(CNXyl)(CNR)]+(R=Xyl or t-Bu) with open bioctahedral structures to di-μ-chloro edge-sharing bioctahedral structures with no Re–Re bond

Abstract The diamagnetic dirhenium(II) complexes [Re2X3(μ-dppm)2(CO)(CNXyl)2]O3SCF3, where dppm=Ph2PCH2PPh2, XylNC=xylyl isocyanide and X=Cl (3a) or Br(3b), in which the cations possess the Re–Re triply bonded, open bioctahedral structure [(XylNC)2XRe(μ-dppm)2ReX2(CO)]O3SCF3, convert to the paramagnetic di-μ-halo bridged complexes [(XylNC)(CO)Re(μ-X)2(μ-dppm)2ReX(CNXyl)]O3SCF3, X=Cl (4a) or Br (4b), in very high yield when their solutions in 1,2-dichloroethane are heated to reflux for ca. 24 h. This isomerization involves a switch from a ReRe bonded structure (Re–Re distance=2.383(1) A in 3a) to one in which no Re–Re bond is present (Re–Re distance=3.321(1) A in 4a). The complex cations in 4a and 4b are formulated as mixed-valence Re(I)–Re(III) species, and their formation represents the first example of the isomerization of a multiply bonded dimetal complex to one in which no metal–metal bond is present. The related thermal isomerizations of the Re–Re triply bonded, mixed-isocyanide ligand complexes [Re2X3(μ-dppm)2(CO)(CNXyl)(CN-t-Bu)]O3SCF3, X=Cl or Br, have also been examined.

Reactions of the polyhydride complex ReH7(dppe) (dppe = Ph2PCH2CH2PPh2) with pyridine-2-carboxylic acid, 1-isoquinolinecarboxylic acid, 2-hydroxy-6-methylpyridine and 2-mercaptoquinoline. synthesis and structural characterization of seven-coordinate monohydrido complexes of rhenium(iii)

Abstract The thermal reactions of ReH 7 (dppe) (dppe = Ph 2 PCH 2 CH 2 PPh 2 ) with pyridine-2-carboxylic acid (Hpic), 1-isoquinolinecarboxylic acid (Hisoquin), 2-hydroxy-6-methylpyridine (Hmhp) and 2-mercaptoquinoline (Hmq) in refluxing benzene afforded the monohydridorhenium(III) species ReH(L) 2 (dppe) [L = pic (1a), isoquin (1b), mhp (1c), mq (1d)]. While analogous complexes have been prepared previously from ReH 7 (PPh 3 ) 2 in the case of L = pic, isoquin and mhp, the reactions between ReH 7 (PPh 3 ) 2 and the ligands 2-hydroxyquinoline and 2-mercaptoquinoline are dependent on the choice of reaction solvent; the rhenium hydride complexes ReH 4 (L)(PPh 3 ) 2 (L = hq or mq) and ReH(hq) 2 (PPh 3 ) 2 have been isolated in a pure state. 1 H and 31 P NMR spectral measurements on the seven-coordinate species 1a-d show that these compounds are stereochemically rigid at room temperature. The solution structures are in accord with the solid state structures of 1c and 1d, as determined by X-ray crystallography. Copyright

The syntheses and structures of salts of the octachlorodirhenate(III) and octachlorodiosmate(III) anions with the 1,2-bis(triphenylphosphonium) ethane cation

Abstract The reactions of cis-Re2(O2CCH3)2Cl4(py)2 or (n-Bu4N)2Re2Cl8, with PR, (R = Cy or Ph) in refluxing 1,2-dichloroethane afford the bis-phosphonium salts (R3PCH2CH2PR3)Re2Cl8; the crystal structure of the derivative where R = Ph shows that this is only the second example of a salt of the [Re2Cl8]2 anion in which a 3-fold orientational disorder of the ReRe units is encountered. A cation exchange reaction between (Ph3PCH2CH2PPh3)CI2 and (n-Bu4N)2Os4Cl8 affords (Ph3PCH2CH2PPh3)Os2Cl8,, which possesses an OsOs bond distance of 2.1896(3) A and is the second example of a crystal structure of a [Os2Cl8]2− salt in which a fully staggered rotational geometry is present.

Reactions of monodentate tertiary phosphines with the dirhenium(II) alkyne complexes [Re2Cl3(μ-dppm)2(CO)-(η2-RCCH)]X (X = PF6 or O3SCF3) to form ylides☆

The η2-alkyne adducts [Re2CL3(μ-dppm)2(CO)(η2-RCCH)]XR = H, Prn, Bun or Ph; X = PF6 or O OSCF3 have been reacted with monodentate tertiary phosphines PR3 (R3 = Me3, Et3, Me2PH or Me2Ph of Me PHa2 to afford in hight yield (> 600% a new class of resonance stabilized ylides of composition [Re2Cl3(μ-dppm)2(CO)(C(R)CH(PR3)]X. These diamagnetic complexes have been characterized by IR, 1H NMR and 31P{1H} NMR spectroscopies and cyclic voltammetry, and the structure of a representative example determined by single crystal X-ray crystallography. Crystal data for [Re2Cl3(μ-dppm)2(CO)(C(Prn)CH(PMe2Ph))]SO3 CF3·0.83C7H8 at 173 K: monoclinic space group Pn (No. 7), a = 16.404(4), b = 11.907(2), c = 19.866(2) A, β = 110.58(1)°, V = 3632(2) A3, Z = 2. The structure was refined in full-matrix least-squares to R=0.052 (Rw=0.068) for 4156 data with I > 3σ(I). This structure determination shows that the basic geometry present in the parent complexes [Re2Cl3(μ-dppn)2(CO)(η2- RCCH)]X is retained, the principal difference being the conversion of the η2-alkyne ligand RCCH to the η1-bound ylide C(R)CH(PR3). The ReRe bond length of 2.311(1) A signifies the retention of an Re≡Re bond.

The reactions of dirhenium complexes with tris(diphenylphosphino)methane. The conversion of the dirhenium(III) complex cis-Re2(O2CCH3)2Cl4(py)2 to mononuclear trans-ReCl2[η2-HC(PPh2)3]2☆

Abstract The reaction of tris(diphenylphosphino)methane (HC(PPh2)3, abbreviated tripod) with Re2Cl4(PMe3)4 in hot ethanol leads to the formation of Re2Cl4(μ-dppm)(PMe3)2 as the major product (dppm = Ph2PCH2PPh2). The compound trans-ReCl2[η2-HC(PPh2)3]2 was obtained as a minor product from the reaction of cis-Re2(O2CCH3)2Cl4(py)2 with HC(PPh2)3. This complex, which was structurally characterized by X-ray crystallography, is an example of a small but growing class of mononuclear rhenium(II) complexes that have a trans-ReCl2P4 octahedral geometry. Crystal data at +20 °C: triclinic space group P 1 (No. 2), a = 10.867(1), b = 13.157(1), c = 13.4060(9) A , α = 109.279(6), β = 98.477(5), γ = 112.198(6)°, V = 1591.9(6) A 3 , Z = 1 . The structure was refined by full-matrix least-squares to R = 0.034 (Rw = 0.043) for 5005 data with I>3σ(I).

Reactions of the Dirhenium(II) Complexes Re2X4(μ-dppm)2 (X=Cl, Br; dppm=Ph2PCH2PPh2) with Isocyanides. Part XV: A Fifth Structural Isomer of the [Re2Cl3(μ-dppm)2(CO)(CNXyl)2]+ Cation (Xyl = 2, 6-Dimethylphenyl)

The reaction of the unsymmetrical, coordinatively unsaturated dirhenium(II) complex [(XylNC)(OC)CIRe(μ-dppm)2ReCl2]O3SCF3 (dppm = Ph2PCH2PPh2) with one equivalent of XylNC in CH2Cl2 affords a fifth structural isomer of the [Re2Cl3(μ-dppm)2(CO)(CNXyl)2] + cation; this is believed to have a CO-bridged structure of the type [(XylNC)ClRe(μ-Cl)(μ-CO)(μ-dppm)2ReCl(CNXyl)]+. The latter complex reacts with a further equivalent of XylNC in the presence of Tl+ to form the [Re2Cl2(μ-dppm)2(CO)(CNXyl)3]2+ cation, which has been shown by IR spectroscopy, and by the X-ray crystallographic characterization of its neutral congener Re2Cl2(μ-dppm)2(CO)(CNXyl)3, to contain a very weak and unsymmetrical CO bridge.

Reactions of the multiply-bonded dirhenium(II) complexes Re2X4(μ-dppm)2(CNR) (X = Cl or Br; R = t-Bu or xylyl) with alkynes. Structural characterization of [Re2Cl3(μ-dppm)2(CN-t-Bu)(η2-HCCH)]O3SCF3 and a comparison with the related carbonyl species(1)

SummaryThe reactions of the triply-bonded monoisocyanide complexes Re2X4(μ-dppm)2(CNR) (X = Cl or Br; dppm = Ph2PCH2PPh2; R = t-Bu or xylyl) with the alkyne ligands HCCH and n-PrCCH in the presence of TlO3SCF3 afford the complexes [Re2X3(μ-dppm)2-(CNR)(η2-HCCR)]O3SCF3 (R = H or n-C3H3). The structure of this set of complexes has been established by an X-ray structure determination on a single crystal of composition [Re2Cl3(μ-dppm)2(CN-t-Bu)(η2-HCCH)]-O3SCF3·CH3C(O)OC2H5(2a). The structure of the dirhenium(II) cation, [(t-BuNC)Cl2Re(μ-dppm)2ReCl-(μ2-HCCH)]+, involves different coordination numbers for the two Re centres and an anti arrangement of the t-BuNC and μ2-HCCH ligands. The 625-01 bond length of 2.3171(5) Å accords with the retention of a 625-02 bond.

Reactions of the dirhenium(II) complexes Re2X4(dppm)2 (X= Cl, Br; dppm = Ph2PCH2PPh2) with isocyanides. Part IX. New isomeric forms of the mixed carbonyl-isocyanide dirhenium(II) Complexes Re2 Cl4(dppm)2(CO)(CNxyl) and [Re2Cl3(dppm)2(CO)(CNxyl)2]O3SCF3 The X-ray crystal structure of [(xyl NC)2ClRe(μ-dppm)2ReCl2(CO)] O3SCF3

The monocarbonyl complex Re2Cl4(µ-dppm)2(CO) reacts with xylyl isocyanide in acetonitrile to afford the bioctahedral complex (CO)Cl2Re(µ-dppm)2 ReCl2(CNxyl), 2b. This is a different structural isomer from the edge-sharing bioctahedral complex Cl2Re(µ-Cl)(µ-dppm)2ReCl(CNxyl) or this same stoichiometry which A formed when acetone is be reaction solvent. The complex2b reacts with a further equivalent of xylNC in the presence of TlO3SCF3 in dichloromethane to form a red complex of composition [Re2Cl3(µ-dppm)2 (CO)(CNxyl)2]O3SCF3. 3, which has the open bioctahedral structure [(xylNC)2ClRe(µ-dppm)2ReCl2(CO)]O3SCF3. This is a third isomeric form of this dirhenium cation: the previously isolated green and yellow forms have edge-sharing bioctahedral structures. Crystal data for3 at 295 K: orthorhombic space group Pbca (No. 61) witha=22.654(5) Å,b=22.717(4) Å,c=27.324(4) A,V= 14061(7) Å3, andZ = 8. The structure was refined to R = 0.059 (R, = 0.134 ) for 14164 data. The Re-Re distance is 2.3833(8) Å.

Stable boat and chair isomers of dimetal complexes containing the[M2(µ-dppm)2] unit (M = Re; dppm =Ph2PCH2PPh2)

Reactions of the triply bonded complexes [Re 2 Br 3 (µ-dppm) 2 (CO)(CNR)]Y (dppm = Ph 2 PCH 2 PPh 2 ; R = 2,6-dimethylphenyl; Y = O 3 SCF 3 , PF 6 ) with RNC afford edge-sharing bioctahedral complexes of the type [Re 2 (µ-Br) 2 (µ-dppm) 2 Br(CO)(CNR) 2 ]Y, which are shown to contain Re–Re single bonds and exist in novel isomeric forms with boat and chair conformations for the Re 2 (µ-dppm) 2 unit.