Walter Schuh

Novel route to carbodiphosphoranes producing a new P,C,P pincer carbene ligand

The reaction of PdCl2, dppm and CS2 in CH(2)Cl(2)/MeOH results in the palladium carbodiphosphorane complex [Pd(Ph(2)PCH(2)Ph(2)PCPPh(2)CH(2)PPh(2)-P,C,P)Cl]Cl.

Homochiral Self Recognition in Gold-Phosphane-Helicates

Treatment of Au(SMe2)Cl with a mixture of (R*,S*)- and (R*,R*)-(±)-p4 (p4 = 1,1,4,7,10,10-hexaphenyl-1,4,7,10-tetraphosphadecane) and TlOTf produces [Au4(R,S-p4)2](OTf)4 (1) and a racemic compound of [Au4(R,R-p4)2](OTf)4 and [Au4(S,S-p4)2](OTf)4 (2). Compounds 1 and 2 were isolated as colorless crystals and characterized by single crystal X-ray diffraction. In both 1 and 2, four gold atoms are bridged by two p4 ligands. The structure of 1 is a meso-helicate composed of a P, an M and a central achiral domain. The ligands exhibit a head-to-head arrangement. The structures of 2 consist of a non-palindromic double helix. In both 1 and 2 the R centers induce a left-handed (M) and the S centers a right-handed (P) helicity. The helical elements of both 1 and 2 are unsaturated and show Au···Au interactions. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Arsine stabilized triangulo-[Hg3]4+ clusters

Abstract Subvalent mercury clusters [Hg 3 (LL) 3 ] 4+ with LL=dpam (dpam=Ph 2 AsCH 2 AsPh 2 ) or Ph 2 AsCH 2 PPh 2 and dpam–dppm (dppm=Ph 2 PCH 2 PPh 2 ) or dpam–Ph 2 AsCH 2 PPh 2 mixed ligand complexes were obtained by reaction of [Hg 2 ] 2+ with the ligands or by reduction of a mixture of [Hg(Me 2 SO) 6 ](O 3 SCF 3 ) 2 and the ligands with elemental mercury. Whereas the equilibrium 2Hg 2+ +Hg⇌[Hg 3 ] 4+ is far to the right in the presence of the ligands dpam or dppm, only ca. 20% conversion is observed for Ph 2 AsCH 2 PPh 2 . The clusters are characterized by FAB MS and multinuclear NMR spectroscopy. The 199 Hg– 199 Hg coupling constants of [Hg 3 (μ-dpam) 2 (μ-dppm)](O 3 SCF 3 ) 4 have values of 17 800 and 23 600 Hz. The fragmentation of [Hg 3 (μ-dpam) 3 ](O 3 SCH 3 ) 4 gives [Hg 2 (μ-dpam) 2 ](O 3 SCH 3 ) 4 which is characterized by single-crystal X-ray diffraction.

Host–guest interactions of the cluster [triangulo-Hg3(μ-dppm)3]4+ (dppm=bis(diphenylphosphino)methane) with halides and pseudohalides

Abstract The complexes [ triangulo -Hg 3 (μ-dppm) 3 X n ] (4− n )+ (X=Cl, Br and I, n =1, 2) are formed in a small extent upon addition of halides to the cationic subvalent cluster [ triangulo -Hg 3 (μ-dppm) 3 ] 4+ , whereas SeCN − and CN − cause quantitative fragmentation. The cluster [ triangulo -Hg 3 (μ-dppm) 3 (SCN) 2 ] 2+ is produced either by the reaction of [ triangulo -Hg 3 (μ-dppm) 3 ] 4+ with thiocyanate or via reduction of a mixture of Hg(SCN) 2 , [Hg(Me 2 SO) 6 ](O 3 SCF 3 ) 2 and 3 mequiv. of dppm with elemental mercury. The X-ray structure of [Hg 3 (μ-dppm) 3 (SCN) 2 ](O 3 SCF 3 ) 2 shows a Hg 3 triangle (Hg–Hg distances 286.60(14), 279.32(12) and 281.2(2) pm) spanned by three dppm ligands. The thiocyanate ions are positioned nearly parallel to the Hg 3 plane in the two cavities formed by the Hg 3 group at the bottom and the phenyl groups of the dppm ligands as the walls (Hg1–S1 277.5(6) and Hg3–S2 278.4(6) pm). Phosphorus-31 solution NMR indicates a rapid rotation of the SCN − ligands about the Hg 3 triangle within the cavity.

Chemistry at the Sterically Shielded Mercury Centre of the [(η4‐pp3)PtHg] Fragment

Treatment of [(η4-pp3)PtH]OTf (pp3 = tris[2-(diphenylphosphanyl)ethyl]phosphane) with PhHgCl gave [(η4-pp3)PtHgCl]OTf (1a) in good yield. The reaction of 1a with the carbonylmetallates [Mn(CO)5]− or [Co(CO)4]− and TlOTf produced the linear trinuclear clusters [(η4-pp3)PtHgMn(CO)5]OTf (2) or [(η4-pp3)PtHgCo(CO)4]OTf (3), respectively. The reaction of 1a with PR3 and TlOTf gave [(η4-pp3)PtHg(PR3)](OTf)2 (4: R = nBu; 5: R = Ph), with Ph2P(CH2)nPPh2 (n = 1, 2) or dppmSe [dppmSe = bis(diphenylphosphanyl)methane monoselenide] adducts in which the diphosphane/diphosphane monoselenide adopts a monodentate, bridging or chelating bonding mode depending on the ligand and the stoichiometry. The mercury-bound phosphane complexes extrude elemental Hg within hours or days. The new compounds were characterised by multinuclear NMR spectroscopy and, in part, by single-crystal X-ray diffraction. The NMR investigations yielded unprecedented parameters, e.g. very large 31P coordination chemical shift for a monodentate phosphane or 2J(Hg−Pt−P) couplings that were two to three times larger than Hg−P one-bond couplings within the same complex.

1 J(199Hg199Hg) values of up to 284 kHz in complexes of [Hg–Hg]2+ with crown ethers: the largest indirect coupling constants

The values of the 1J(199Hg199Hg) coupling constant in solution of the asymmetric dimercury(2+) complexes with the stoichiometries Hg22+/18-crown-6 and Hg22+/18-crown-6/15-crown-5 are 220300 and 284100 Hz, respectively, representing the largest scalar couplings measured.

Ligand assisted dimerisation of a diplatinum(2+) system: a straightforward high yield access to tetranuclear platinum clusters

The iodide induced dimerisation of a dppm-/diphenylphosphido-bridged Pt22+ system leads to a 56 CVE Pt4 butterfly cluster which is diprotonated by HO3SCF3 to give a 60 CVE rectangular Pt4 cluster.

Crystal structure of an iridium(III) complex of the [C(dppm)2] PCP pincer ligand system and its conjugate CH acid form

The crystal structures of [IrIII(CO)(C(dppm)2-κ 3P,C,P′)ClH]Cl and [IrIII(CO)(CH(dppm)2-κ 3P,C,P′)ClH]Cl2 have been determined. Both complexes show a slightly distorted octahedral coordinated IrIII centre. The PCP pincer ligand system is arranged in a meridional manner.

Crystal structures of four new iridium complexes, each containing a highly flexible carbodi­phos­phorane PCP pincer ligand

The synthesis and crystal structures of four iridium–PCP pincer complexes, each containing a highly flexible carbodiphosphorane PCP pincer ligand, are discussed.

P(CH2CH2PPh2)3 Bridged Group 10 dimetal centres

The complexes [M(η4-PP3)Cl]Cl (M = Ni, Pd or Pt, PP3 = P(CH2CH2PPh2)3) were treated with the metal based nucleophiles [Pt(PPh3)2(C2H4)], [Pt(η2-bicyclo(2.2.1)hept-2-ene)3] or [Pd2(dba)3] (dba = dibenzylideneacetone) to produce PP3 bridged metal–metal bonded homo- and heterodinuclear complexes in which the central and one terminal phosphorus of the PP3 ligand are chelated to one metal whilst the other two terminal phosphorus atoms bridge to the second metal centre. The products are characterised by 31P and 195Pt NMR spectroscopy; X-ray crystal structures were determined for [Pt2(PP3)(PPh3)Cl]Cl and [Pd2(PP3)Cl2].