Search

The reaction of various ylides of general formula RCO··[graphic omitted] [R = Ph or m- or p-MeC6H4; X = N or CH; Y = pyridine, NMe3, or PPh3(most work has been carried out with PhCO··[graphic omitted]H5C5= L)] with halide salts of palladium(II), platinum(II), rhodium(III), and iridium(III) affords products containing metallated betaines. Spectroscopic data (i.r., 1H, and 13C n.m.r.) show unambiguously that the aryl group R has become metallated in a position ortho to the carbonyl group and also that the ylide is bidentate (L′)via the group X. There is good evidence to indicate that the mechanism of the reaction involves preliminary co-ordination of the ylide followed by intramolecular electrophilic attack by the metal. Palladium tends to give di-µ-halogeno-complexes, [{Pd(L′)Y}2], whereas in the case of platinum it is possible to prepare [PtL′2] which has cis-Pt–C bonds. Rhodium affords ionic complexes, cis-[RhL′2(H2O)2]Z (Z = Cl, Br, I, or BPh4), which with 2,2′-bipyridyl give [RhL′2(bipy)]Cl. Iridium gives a non-ionic derivative, [IrL′2(H2O)Cl],3H2O. Reactions of the complexes with Ph3P or Bun3P give new complexes containing phosphine oxide such as [PdL′{P(O)Ph3}]Cl, [PtL′{P(O)Ph3}Cl], [RhL′2{P(O)-Bun3}Cl], and [IrL′2{P(O)Ph3}Cl]. The Pd–Cl and Pt–Cl bonds are trans to nitrogen when L = PhCO··[graphic omitted]H5C5. Carbon monoxide reacts reversibly with palladium and iridium complexes of PhCO··[graphic omitted]H5C5to give [PdL′(CO)Cl] and [IrL′2(CO)2]Cl. I.r. evidence suggests CO to be cis to the Pd–C bond in the palladium complex and other observations suggest that the mode of formation is not simple.

The synthesis and crystal and molecular structure of the chloroperchloratotri(o-tolyl)phosphinemercury(II) dimer are reported. The compound [HgP(o-tolyl)3ClClO4]2 belongs to the orthorhombic space group Pbca [Formula: see text] with a = 12.218(2), b = 13.814(2), c = 26.074(3) Å, and Z = 4. The structure was refined to a final R of 0.046 for 2584 reflections measured by diffractometer. The crystal structure consists of discrete centrosymmetric dimeric molecules of [HgP(o-tolyl)3ClClO4]2 separated by normal van der Waals distances. The unique mercury atom forms two strong bonds (Hg—P 2.395(3), Hg—Cl(1) 2.332(4) Å) which deviate from linearity (P—Hg—Cl 164.1(1)°) and two weak bonds (Hg—O(1) 2.73(2) to the perchlorato group, Hg—Cl(1 *) 3.109(4) Å linking the mercury atoms about centers of symmetry). The four-fold coordination geometry about each mercury can be described as trigonal bipyramidal with the phosphorus and Cl(1) axial, and one equatorial site unoccupied. Intramolecular interactions are discussed with the assistance of cone angle calculations and a ligand profile for P(o-tolyl)3 (θ = 198°). Vibrational and 31P nmr spectra data are also presented for [HgP(o-tolyl)3ClClO4]2.

Tris(tert-butyl)phosphine and tri(o-tolyl)phosphine form 1:1 complexes with mercury(II) halides and with mercury(II) thiocyanate. Physicochemical measurements, i.e. conductance, molecular weight determinations, infrared and Raman spectra indicate a dimeric structure of C2h skeletal symmetry. The Hg—X and Hg—P stretching frequencies for all complexes have been assigned.

The title complex has been synthesized and crystallizes in a 1 : 1 ratio with dichloromethane in the monoclinic space group C2/c with a= 22.100(3), b= 9.961 (3), c= 21.516(3)A, β= 113.19(1)°, and Z= 4. The structure has been solved by Patterson and Fourier methods and refined by full-matrix least-squares techniques to a final R of 0.036 for 3 073 observed reflections measured by diffractometer. The dichloromethane is disordered over three equally populated sites around the crystallographic two-fold axis. The trans-[Ptl2{P(C6H4Me-o)3}2] molecule resides on a crystallographic centre of symmetry with Pt–I and Pt–P distances of 2.622(1) and 2.348(2)A respectively. The failure of this complex to undergo intramolecular metallation can be explained by the steric effects of the P(C6H4Me-o)3 ligand, which are described by cone-angle calculations (θ= 183°) and a ‘ligand profile’.

The synthesis and crystal and molecular structure of the dinitrato(trimesitylarsine)mercury(II) dimer are reported. The compound [HgAs(mesityl)3(NO3)2]2 belongs to the monoclinic space group P21/c[Formula: see text] with a = 20.001(2), b = 17.591(5), c = 16.553(2), β = 99.991(6), and Z = 4; the asymmetric unit contains two independent half dimers. The structure was refined to a final R of 0.0458 for 2631 observed reflections measured by diffractometer with 2 3(NO3)2]2 separated by normal van der Waals distances. The mercury coordination in both dimers I and II is characterized by three strong, nearly coplanar bonds (in I Hg—As 2.476(3), Hg—O 2.41(2) and 2.20(2), and in II Hg—As 2.482(3), Hg—O 2.28(2) and 2.39(2), and three weaker Hg—O bonds in the range 2.55–2.90 Å. Both independent trimesitylarsine ligands have the same regular propeller conformation (Hg—As—C—C torsion angles of 45 to 50°) and the largest C—As—C angles (mean value 112.5(8)°) yet determined. The As(mesityl)3 cone angle is 202°. The two independent dimers differ primarily in the orientation of the non-bridging nitrato groups. Nitrato vibrational and arsine 1H nmr data are also presented for [HgAs(mesityl)3(NO3)2]2, which becomes monomeric in dichloroethane solution.

Reaction of PdX2·2PhCN(X = Cl or Br) with 2,2,NN-tetramethylpent-4-enylamine (1a) gives complexes (2) of stoicheiometry PdX2·(1a) in which Pd–X has added to the olefinic bond to generate a seven-membered chelate ring. In contrast, 2,2-dimethylpent-4-enyl methyl sulphide (1b) initally gives labile olefinic complexes, which readily rearrange to the derivatives (5a) and (5b) of 2,2-dimethylpent-(E)-3-enyl methyl sulphide (13). Variable-temperature 1H n.m.r. studies show that at low temperatures (5a) and (5b) exist in solution as pairs of epimers at sulphur, while heating leads first to equilibration of the epimers and then to labilisation of the metal–olefin bond. The π-allyl species (6a) and (6b) have been prepared from (5a) and (5b). X-Ray structures of (5a) and (6a) are reported. Crystals of (5a) are monoclinic, space group P21/n with Z= 4 in a unit cell of dimensions a= 8.365(2), b= 15.068(2), c= 9.595(1)A, and β= 94.00(1)°. Crystals of 6(a) are monoclinic, space group P21/c, with Z= 4 in a unit cell of dimensions a= 6.583, b= 12.462, c= 12.859(6)A, and β= 96.20(5)°. Both structures have been solved by the heavy-atom method and refined by full-matrix least-squares calculations to R= 0.023 for 2 414 reflections for (5a) and to R= 0.046 for 2 515 reflections for (6a). The five-membered chelate rings in (5a) and(6a) have C(2)-envelope conformations. In (5a) principal dimensions are Pd–Cl 2.313 and 2.320(1), Pd–S 2.269(1), and Pd–C 2.195 and 2.231(3)A, and the interplanar angle between the PdCl2S plane ad the Pd–ethylenic carbon plane is 96.0°. In (6a) dimensions are Pd–Cl 2.381(1), Pd–S 2.364(1), Pd–C 2.089, 2.120, and 2.173(5)A; the plane of the allyl moiety forms a dihedral angle of 116.4° with the PdSCIC(5) plane.

Mercury(II) acetate complexes of the type (R3P)nHg(OAc)2, where n = 1 and 2, and R3P = (p-tolyl)3P, (p-F-C6H4)3P, Ph2MeP, Ph2EtP, and PhEt2P have been prepared in good yields. Only the 1:1 adduct is formed with (o-tolyl)3P. Conductance measurements in nitromethane show that these complexes are non-electrolytes. The 1:1 adducts are monomeric in dichloroethane but the 1:2 adducts are extensively dissociated. Tentative assignments for ν(COO), ν(Hg—O), ν(Hg—P) are made from the infrared and Raman spectral data. The correlation of the coordination chemical shifts, Δδ(31P), with the coupling constants 1J(199Hg–31P) of the complexes is discussed with respect to the bulkiness and the basicity of the phosphine ligands.

The ligands 2,2-dimethylbut-3-enyl methyl sulphide (1a) and 2,2-dimethyl-2-2-silabut-3-enyl methyl sulphide (1b) form analogous sets of complexes with a series of silver salts. Thus, 1 : 1 complexes have been obtained from Ag[BF4], Ag[ClO4], Ag[NO3], and Ag[O2CCF3], 1 : 2 (Ag : ligand) complexes from Ag[BF4] and Ag[ClO4], and 2 : 1 (Ag : ligand) complexes from Ag[NO3]. In the solid state (i.r. and X-ray) the ligands are chelated, while in solution (1H n.m.r.) both the Ag–sulphur and Ag–olefin bonds are labile even at low temperatures (–80 °C). Crystal-structure analyses have been completed on Ag[BF4]·2(1a), Ag[ClO4]·(1a), Ag[NO3]·(1a), and Ag[O2CCF3]·(1a). The complex Ag[BF4]·2(1a) contains discrete [Ag·2(1a)]+ cations (which have two-fold crystallographic symmetry) and disordered BF4– anions. Polymeric structures have been found for the remaining three complexes. In [Ag·(1a)][ClO4] polymeric cation chains are present, while the perchlorate ions are not co-ordinated to silver. In Ag[NO3]·(1a) the nitrato-group is bidentate (Ag–O 2.537 and 2.647 A), whereas the carboxyl group in Ag[O2CCF3]·(1a) is predominantly unidentate (Ag–O 2.29 and 2.99 A). In all four structures the five-membered –Ag–S–C(1)–C(2)–C(3)– ring adopts a C(2) envelope conformation. The olefin co-ordination is defined by the S–Ag–C(3)C(4) torsion angles 148.6 in Ag[BF4]·2(1a), 140.9 in Ag[ClO4]·(1a), 158.7 in Ag[NO3]·(1a) and 140.2° in Ag[O2CCF3]·(1a). Crystals of Ag[BF4]·2(1a) are monoclinic, space group C2/c, with four formula units in a cell of dimensions a= 10.838(2), b= 11.720(2), c= 16.355(2)A, β= 105.02(1)°, R= 0.049 for 645 observed reflections. Crystals of Ag[ClO4]·(1a) are orthorhombic, space group P212121, with four formula units in a cell of dimensions a= 8.229(3), b= 10.645(3), c= 13.917(3)A, R= 0.066 for 1 259 reflections. Crystals of Ag[NO3]·(1a) are monoclinic, space group P21/c, with four molecules in a cell of dimensions a= 11.049(1), b= 7.823(1), c= 14.352(3)A, β= 118.392(7)°, R= 0.049 for 1 653 reflections. Crystals of Ag[O2CCF3]·(1a) are monoclinic, space group P21/b, with four molecules in cell of dimensions a= 10.194(3), b= 15.784(5), c= 8.125(4)A, γ= 95.49°, R= 0.099 for 846 reflections.

Eight members of the series of 1 : 1 complexes of palladium(II) halides (chloride, bromide, and iodide) with the ligands 2,2,NN-tetramethylbut-3-enylamine (1a), 2,2-dimethylbut-3-enyl methyl sulphide (1b), and 2,2-dimethyl-2-silabut-3-enyl methyl sulphide (2b) have been isolated. The remaining complex, Pdl2·(2b), is unstable, disproportionating to give Pdl2·2(2b). Infrared and 1H n.m.r. data are reported. In solution all the 1 : 1 complexes, even the iodides, are chelated and the ring apparently adopts similar conformations. Variable-temperature 1H n.m.r. studies of two exchange processes, labilisation of the metal–olefin bond and, for the sulphur chelates, inversion at sulphur, are discussed.