The reaction of meta-phenylene-bis(1-methyl-1H-imidazole-2(3H)-selone) with [Pd2(μ-Cl)2(2-C6H4CH2NMe2)2] in dry benzene and glacial acetic acid resulted in the formation of an unsymmetrical 5,6-membered C,C,Se-Pd(II) pincer complex through C-H bond activation and extrusion of one selenium. This is the first example of a C,C,Se-Pd(II) complex wherein the central Pd(II) is simultaneously coordinated to a selone and an N-heterocyclic carbene. The chelated complex of the type [PdL2](2+)2[PF6](-) (L = bis(selone)) was isolated from the reaction of the bis(selone) with [PdCl2(PhCN)2] and NH4PF6. The unsymmetrical pincer complex was studied for Heck activity revealing its application as an acceptable catalyst in coupling of iodobenzene with acrylates and styrene.

Organochalcogenolate-bridged cyclometalated palladium(II) complexes of the formulae, [Pd-2(mu-Epy)(2)(Me2NCH2C6H4-C,N)(2)] (2) (E = S (2a), Se (2b)), [Pd-2(mu-SAr)(mu-Cl)(Me2NCH2C6H4-C,N)(2)] (3) (Ar = Ph (3a), Mes (Mes = 2,4,6-Me3C6H2) (3b)) and [Pd-2(mu-SeAr)(2)(Me2NCH2C6H4-C,N)(2)] (4) (Ar = Ph (4a), Mes (4b)), have been synthesized by the reactions of [Pd-2(-Cl)(2)(Me2NCH2C6H4-C,N)(2)] with lead or sodium salts of the chalcogenolate ligand. These complexes have been characterized by elemental analysis, mass spectral data, and NMR (H-1 and Se-77{H-1}) spectroscopy. The molecular structure of 2, determined by single crystal X-ray diffraction analysis, revealed a Epy-bridged head-to-tail arrangement in which the eight-membered "(PdECN)(2") ring adopts a distorted twist boat conformation. The Pd center dot center dot center dot center dot Pd separation in 2a is within the van-der-Waals interaction but in 2b it is too large to support the presence of any metal-metal interaction. The thermal behavior of these complexes has been studied by thermogravimetric analysis.

Bis(2,4,6-trimethylphenyl) selenoxide has been synthesized by oxidation of bis(2,4,6-trimethylphenyl) selenide with aqueous H2O2 and characterized by elemental analysis and NMR spectroscopy (H-1, C-13{H-1} and Se-77{H-1}). The single crystal X-ray diffraction analysis reveals that the selenium atom adopts a trigonal pyramidal configuration. The reactions of bis(2,4,6-trimethylphenyl) selenoxide with various thiols and other proton donor species in CDCl3 have been studied by Se-77{H-1}; NMR spectroscopy that with thiols at room temperature regenerated the selenide. The data indicate that the selenoxide acts as a hydrogen bond acceptor to give Mes(2)Se=O center dot center dot center dot HX (Mes = 2,4,6-trimethylphenyl or mesityl) species.

Reactions of [Pt2(μ-Cl)2(C8H12OMe)2] (1) (C8H12OMe=8-methoxy-cyclooct-4-ene-1-yl) with various anionic chalcogenolate ligands have been investigated. The reaction of 1 with Pb(Spy)2 (HSpy=pyridine-2-thiol) yielded a binuclear complex [Pt2(Spy)2(C8H12OMe)2] (2). A trinuclear complex [Pt3(Spy)4(C8H12OMe)2] (3) was isolated by a reaction between 2 and [Pt(Spy)2]n. The reaction of 1 with HSpy in the presence of NaOMe generated 2 and its demethylated oxo-bridged tetranuclear complex [Pt4(Spy)4(C8H12-O-C8H12)2] (4). Treatment of 1 with ammonium diisopropyldithiophosphate completely replaced C8H12OMe resulting in [Pt(S2P{OPri}2)2] (5), whereas non-rigid 5-membered chelating ligand, Me2NCH2CH2E−, produced mononuclear complexes [Pt(ECH2CH2NMe2)(C8H12OMe)] (E=S (6), Se (7)). These complexes have been characterized by elemental analyses, NMR (1H, 13C{1H}, 195Pt{1H}) and absorption spectroscopy. Molecular structures of 2, 3, 4, 5 and 7 were established by single crystal X-ray diffraction analyses. Thermolysis of 2, 6 and 7 in HDA gave platinum nanoparticles.

Reactions of [Pt(2)(mu-Cl)(2)(C(boolean AND)P)2] (C(boolean AND)P - CH(2)C(Me(2))PBu(t)2-C,P) with various anionic ligands differing in ligand bite and denticity have been investigated and the resulting products have been characterized by elemental analyses and NMR ((1)H, (13)C, (31)P, (195)Pt) spectroscopy. Stereochemistry of the complexes has been deduced by NMR spectroscopy. Structures of [Pt(2)(mu-SPh)(2)(C(boolean AND)P)(2)], [Pt(2)(mu-pz)(2)(C(boolean AND)P)(2)], [PtCl(Spy)(PBu(3)(t))], [Pt(2)(mu-SCOPh)(2)(C(boolean AND)P)(2)] and [Pt{S(2)P(OPr(i))(2)}(C(boolean AND)P)] have been established by single crystal X-ray diffraction analyses. The complex [Pt(2)(mu-SPh)(2)(C(boolean AND)P)(2)] adopts a sym cis configuration while other binuclear complexes exist in a sym trans configuration. The molecular structure of [Pt{S(2)P(OPr(i))(2)}(C(boolean AND)P)] revealed that complex comprises of two four-membered chelate rings but in solution a dimeric structure based on (195)Pt NMR data has been suggested. (C) 2010 Elsevier B.V. All rights reserved.

The synthesis, structure and spectroscopy of a series of luminescent orthometalated square planar platinum(II) complexes are reported. Reaction of K(2)PtCl(4) with one mole equivalent of 2-phenylpyridine (ppyH) in 2-ethoxyethanol and water (1:1 ratio) resulted in the formation of chloro-bridged dimeric precursor [Pt(2)(mu-Cl)(2)(ppy)(2)], which on further reactions with various anionic one-, two-and three-atom ancillary ligands, having O/N/S donors, yielded mono-and bi-nuclear platinum(II) complexes. Platinum(III) complexes of composition [Pt(2)Cl(2)(mu-Epy)(2)(ppy)(2)] have been isolated with pyE(-) (E = O or S) ligands. These complexes have been characterized by elemental analysis, NMR ((1)H, (31)P, (195)Pt) and absorption spectroscopy. The complexes [Pt(2)(mu-N(boolean AND)N)(2)(ppy)(2)] (N(boolean AND)N = pyrazole and 3,5-dimethylpyrazole); [Pt(S(boolean AND)S)(ppy)] (S(boolean AND)S = ethylxanthate and diisopropyldithiophosphate); [Pt(2)Cl(2)(mu-Epy)(2)(ppy)(2)] (Epy = 2-pyridinol{Opy} and 2-mercaptopyridine {Spy}) and [PtCl(ppy)(PhNC(Me)NHPh)] have been structurally characterized by X-ray crystallography. (C) 2010 Elsevier B.V. All rights reserved.

The reaction of Na 2 PdCl 4 with diaryldiselenide in methanol-acetone yields trans-[PdCl 2 {SeAr(CH 2 COMe)} 2 ] (Ar = 2,4,6-Me 3 C 6 H 2 and 2,4,6-iPr 3 C 6 H 2 ) and [PdCl(SeAr)] n . The intermediate products in these reactions have been characterized by analytical and spectroscopic data and by single crystal X-ray diffraction studies. A plausible mechanism for the formation of arylselenoacetone in these reactions has been suggested.

Thermolysis of [Pt2(µ-OR)2(C8H12OMe)2] (R = Me or Ac) in hexadecylamine (HDA) at 210°C under argon atmosphere gave platinum nanoparticles which were characterized by XRD, EDAX and TEM analysis. Both spherical (∼ 10 nm) and rod-like (∼ 19 nm length with aspect ratio of 2·3) face centred cubic (fcc) platinum metal nanoparticles could be isolated. The thermogravimetric analyses of these complexes revealed that they undergo a single step decomposition leading to the formation of platinum metal powder.

This presentation intends to discuss the design and synthesis of low temperature single source molecular precursors for the synthesis of palladium chalcogenides, both in bulk and nano-size regime. Thus a variety of organochalcogenolates of palladium and platinum differing in nuclearity (mono-, bi-, tri- and hexa- nuclear) have been isolated and characterized by uv-vis, NMR ( 1 H, 13 C, 31 P, 77 Se, 125 Te, 195 Pt) spectroscopy and X-ray crystallography. Thermal behavior of several complexes, such as [Pd(SeCOAr) 2 (PR 3 ) 2 ], [Pd(OAc)(ECH 2 CH 2 CH 2 NMe 2 )] 2 , etc. has been studied by TG analyses. Solvothermal decomposition yields palladium chalcogenides nano-particles (e.g., Pd 7 Te 3 , Pd 17 Se 15 ) which were characterized by XRD, EDAX and SEM method.

Reactions of orthometallated binuclear palladium complexes with NaER, obtained by NaBH4 reduction of R2E2 in methanol, gave complexes, [Pd2(μ-ER)2(C∩Y)2] (HC∩Y=N,N-dimethylbenzylamine (C6H5CH2NMe2), N,N-dimethylnaphthylamine (C10H7NMe2), tri-o-tolylphosphine {P(tol-o)3}; ER=SePh, SeMes, TePh, TeMes (Mes=2,4,6-Me3C6H2). Similar reactions of [Pd2(μ-Cl)2(C10H6NMe2–C,N)2] with Pb(SMes)2 or MesSH in the presence of NaHCO3 gave chloro/thiolato-bridged complex [Pd2(μ-Cl)(μ-SMes)(C10H6NMe2–C,N)2]. The newly synthesized complexes were characterized by elemental analysis, UV–Vis, IR, NMR (1H, 13C, 31P, 77Se, 125Te) spectroscopy. These complexes crystallized out preferentially in sym-cis configuration. A low energy charge transfer transition has been identified from chalcogenolate centers to an emptyπ∗ orbital of cyclometallated ligand in absorption spectroscopy in these complexes. The structures of [Pd2(μ-Cl)(μ-SMes)(C10H6NMe2–C,N)2] (1) and [Pd2(μ-SePh)2(C10H6NMe2–C,N) 2] (3) have been established by single crystal X-ray diffraction analyses. In the former, the two palladium atoms are held together by chloro and thiolato bridges whereas in the latter, the two phenylselenolato ligands bridge two palladium atoms. The pyrolysis of [Pd(μ-TeMes)(C10H6NMe2–C,N)]2 (10) in a furnace gave Pd7Te3 whereas thermolysis in TOPO afforded primarily PdTe2.

The complexes [Pd(μ-ER)(η3-allyl)]2 (ER = EMes; E = S, Se; allyl = C3H5, C4H7) have been isolated by the reaction of [Pb(ER)2]n with [Pd2(μ-Cl)2(η3-allyl)2]. Similar reactions with [Pb(SeCH2CH2NMe2)2]n resulted in the formation of a trinuclear complex [Pd3Cl2(κ2-Se,N-SeCH2CH2NMe2)(η3-allyl)3]. Treatment of [Pd(μ-SR)(η3-C4H7)]2 with [Pd(SMes)2]n in 1:1 ratio yielded [Pd3(μ-SMes)4(η3-C4H7)2]. These complexes were characterized by elemental analyses and mass, UV−vis, and NMR spectroscopy. The structures of [Pd2(μ-EMes)2(η3-C4H7)2] (E = S, Se) were established by single-crystal X-ray diffraction analysis, which revealed a syn configuration. Two new structural motifs for [Pd3Cl2(κ2-Se,N-SeCH2CH2NMe2)(η3-C3H5)3] and [Pd3(μ-SMes)4(η3-C4H7)2] have also been identified. Pyrolysis of [Pd(μ-ER)(η3-C4H7)]2 yielded palladium chalcogenides, which were characterized by powder XRD and EDAX.