Isolation and crystallographic characterization of solvate- and anion-stabilized PCP pincer complexes of palladium(II)

Pincer PCP-Pd(II) complex [PdCl(PCP)] (1) (PCP = ^?CH(CH₂CH₂PPh₂)₂) reacts with AgNO₃ to give [Pd(NO₃)(PCP)] (2). Similar reaction with AgBF₄ gives the aqua complex [Pd(OH₂)(PCP)][BF₄] (3) and the dinuclear complex [{Pd(PCP)}₂(μ-Cl)][BF₄] (4) with singly bridging chloro ligand. All new complexes were characterized by NMR spectroscopy, ESI-MS and single-crystal X-ray diffraction. Complex 1 and the triflate complex [Pd(OTf)(PCP)] (5) are active towards Suzuki–Miyaura coupling between aryl bromides and phenyl boronic acid.     

Allopurinol complexes with first row transition metal perchlorates

Summary Complexes of allopurinol (apH) with Fe^III and several 3d metal(II) (e.g. Fe, Co, Ni and Cu) perchlorates were prepared. The solid complexes isolated included two monomeric hexacoordinated adducts of the type [Fe(apH)₃-(OClO₃) (OH₂)₂]ClO₄ and [Fe(apH)₃(OClO₃)₂(OH₂)]ClO₄, involving N(8)-bound neutral apH ligands, and polymeric Co, Ni or Cu complexes containing both neutral apH and monoanionic ap^- ligands. The latter three complexes involved both N(8)-bound terminal apH and N(1), N(8)- or N(1), N(9)-bound bridging ap^- ligands, and were of the following types: [(apH)₂Cu(ap)] _n (ClO₄) _n , tetrahedral; [(apH)(H₂O)(OClO₃)Co(ap)] _n , pentacoordinated; and [(apH)₂(H₂O)(OClO₃)Ni(ap)] _n , hexacoordinated.Presented in part at the 203rd. American Chemical Society National Meeting; see Ref. 1.     

upper bond 1 start]PdCl[PPh(2)CH(2)CH(2)C[upper bond 1 end]HCH(2)CH(2)PPh(2)] as a precursor to homo- and hetero-metallic species directed by ESMS (electrospray ionisation mass spectrometry)

The cyclometallated Pd compound [upper bond 1 start]PdCl[PPh(2)CH(2)CH(2)C[upper bond 1 end]HCH(2)CH(2)PPh(2)], obtained from PdCl(2)(Ph(2)P(CH(2))(5)PPh(2)) in refluxing DMF (N,N-dimethylformamide), was characterized by NMR and X-ray single-crystal diffraction analysis. The cyclometallation of MCl(2)(Ph(2)P(CH(2))(5)PPh(2))(M = Pd, Pt) to give and its Pt(ii) analogue was probed using electrospray ionisation mass spectrometry (ESMS). The reactivity of towards neutral ligands such as phosphines and pyridines as well as basic metal complexes such as pyridine-thiolate compounds of Au(i), Hg(ii) and Pt(ii) in solution was also investigated. The results showed that the chloride trans to the Pd-C bond is susceptible to ligand replacement. A number of entry metalloligands was examined in an attempt to establish a route to cyclometallated aggregates and clusters.     

Dinuclear PCP pincer complexes from Lewis acidic [Pd(OTf)(PCP)] and basic [Pd(4-Spy)(PCP)] (OTf = triflate; 4-Spy = 4-pyridinethiolate; PCP = (-)CH(CH(2)CH(2)PPh(2))(2))

The Lewis acidic pincer with a labile triflate ligand, viz. [Pd(OTf)(PCP)] (PCP = (-)CH(CH(2)CH(2)PPh(2))(2)) was prepared from [PdCl(PCP)] with AgOTf. It reacts readily with neutral bidentate ligands [L = 4,4'-bipyridine (4,4'-bpy) and 1,1'-bis(diphenylphosphino)ferrocene (dppf)] to give dinuclear PCP pincers [{Pd(PCP)}(2)(micro-L)][OTf](2) (L = 4,4'-bpy, 2; dppf,3). [PdCl(PCP)] also reacts with 4-mercaptopyridine in the presence of KOH to give a Lewis basic pincer with a free pyridine functional group [Pd(4-Spy)(PCP)]4. Its metalloligand character is exemplified by the isolation of an asymmetric dinuclear double-pincer complex [{Pd(PCP)}(2)(micro-4-Spy)][PF(6)] 6 bridged by an ambidentate pyridinethiolato ligand. Complexes 1, 2, 3, 4 and 6 have been characterized by single-crystal X-ray diffraction analyses.     

Urate complexes of dipositive first row transition metal ions

Summary The following complexes were prepared by reacting uric acid (uaH₂) with 3d metal(II) perchlorates in non-aqueous media: trans-[Mn(uaH)₂(OH₂)₄], octahedral, and [Co-(uaH)₂(OH₂)₂] tetrahedral, both involving O(8)-bound hydrogenurate; [Cu(ua)(OH₂)₃], tetrahedral, with the urate dianion binding via a ring nitrogen; and [Ni₂(uaH)₂-(uaH₂)(ClO₄)₂(H₂O)₃] formulated as a pentacoordinated linear polymetric species, involving bidentate bridging hydrogenurate, binding through O(8) and a ring nitrogen.Presented in part at the 4th Chemical Congress of North America (Ref. 1).