Guo-Liang Lu

Synthesis, characterization and structural studies of new heterometallic alkynyl complexes of platinum and Group 11 metals with chelating bis(diphenylphosphino)ferrocene ligand

Reaction of the platinum bis(alkynyl) complex [Pt(dppf)(Cue606CPh) 2 ] ( 1 ) (dppf=bis(diphenylphosphino)ferrocene) with an equimolar amount of Group 11 metal salts [Cu(NCMe) 4 ]BF 4 and AgBF 4 initially gives 1:1 mixed-metal complexes [Pt(dppf)(Cue606CPh) 2 Cu(NCMe)]BF 4 ( 2 ) and [Pt(dppf)(Cue606CPh) 2 Ag]BF 4 ( 3 ) in good yields. Upon standing in solution at room temperature, compounds 2 and 3 rearrange and aggregate to the corresponding diplatinum complexes [{Pt(dppf)(Cue606CPh) 2 } 2 M]BF 4 (M=Cu ( 4 ), Ag ( 5 )) which exhibit an intense molecular ion envelope for the respective cation in their electrospray mass spectra. Compounds 4 and 5 can also be formed when the reaction is performed using a 2:1 molar ratio of 1 and the Group 11 salts. The X-ray crystal structures of 1 , 4 and 5 have been determined. Structures of 4 and 5 reveal that the two square-planar platinum coordination planes in the cation are approximately orthogonal and the Group 11 metal ion is bonded in an η 2 -fashion to four carbonue5f8carbon triple bonds to afford heterometallic pentanuclear Fe 2 Pt 2 M complexes (M=Cu, Ag) in which each platinum center is stabilized by a dppf ligand. Each of the new complexes displays a reversible oxidation couple corresponding to the ferrocenyl unit of dppf and there is less stabilization of the silver in the mixed-metal complex than in the copper congeners.

σ-Acetylide complexes of ruthenium and osmium containing alkynylsilane ligands

The use of the ligands, diethynyldiphenylsilane and 1,3-diethynyltetramethyldisiloxane, in the synthesis of Group 8 metal sacetylide mononuclear complexes is demonstrated. New complexes trans -[(dppm)2ClMC � /CSi(Ph)2C� /CH] (M/Ru 1 ;O s2) and trans -[(dppm)2ClMC� /CSi(Me)2/O/Si(Me)2C� /CH] (M/Ru, 3; Os, 4) featuring different silyl units were prepared from a mixture of cis -[M(dppm)2Cl2] and HC � /CSi(Ph)2C� /CH or HC� /CSi(Me)2/O/Si(Me)2C� /CH in the presence of NaPF6 followed by deprotonation with 1,8-diazabicyclo[5.4.0]undec-7-ene. All the new complexes have been fully characterized by FTIR and NMR spectroscopies and fast atom bombardment mass spectrometry. Single-crystal X-ray structures of 1 and 2 confirm that the two diphosphines adopt a trans geometry at the metal centre and one of the terminal ethynyl groups remains intact. Complexes 1/4 show reversible redox chemistry and their half-wave potentials due to the metal centres are less anodic than those for the starting precursors cis -[M(dppm)2Cl2 ]( M/Ru, Os). # 2003 Elsevier Science B.V. All rights reserved.

Synthesis, structures and electrochemistry of bis(alkynylferrocene) complexes with fluorene spacers

Abstract New bis(alkynylferrocene) complexes with fluorenyl-based spacers [(η 5 -C 5 H 5 )Fe(η 5 -C 5 H 4 )Cue606CRCue606C(η 5 -C 5 H 4 )Fe(η 5 -C 5 H 5 )] (R=fluoren-9-one-2,7-diyl, 1 ; fluorene-2,7-diyl, 2 ; 9-ferrocenylmethylenefluorene-2,7-diyl, 3 ) have been prepared in excellent yields by the Sonogashira coupling reactions of ethynylferrocene with half an equivalent of the corresponding dibromofluorene derivatives BrRBr. All the compounds have been characterized by FTIR, 1 H-NMR and UV–vis spectroscopies and fast atom bombardment mass spectrometry (FABMS). The molecular structures of 1 and 2 have been elucidated by single-crystal X-ray analyses. The redox chemistry of these fluorene-linked biferrocenes has been investigated by cyclic voltammetry and the interaction between the ferrocene units is rather weak in each case. The half-wave potential of the terminal ferrocenyl moieties increases progressively in the order 3 2 1 when the substituent at the 9-position of the central spacer changes from an electron-donating ferrocenyl group (as in 3 ) to an electron-deficient oxo group (as in 1 ). This is consistent with the loss of electron density from the ferrocenyl unit to the net electron-accepting fluorenone through the ethynyl bridge in 1 .

Synthesis, structures and luminescent properties of metal complexes containing 4-[2-(9-anthryl)vinyl]pyridine

Abstract Reactions of the anthracene-containing ligand, 4-[2-(9-anthryl)vinyl]pyridine L 1 , with various metal complexes of Groups 6, 7 and 12 elements, namely, M(CO) 6 (M=Mo, W), M(CO) 5 Br (M=Mn, Re) and MCl 2 (M=Zn, Cd) readily afford new complexes of the stoichiometry M(CO) 5 ( L 1 ) (M=Mo ( 1 ); W ( 2 )), M(CO) 3 Br( L 1 ) 2 (M=Mn ( 3 ); Re ( 4 )) and MCl 2 ( L 1 ) 2 (M=Zn ( 5 ); Cd ( 6 )) in moderate to good yields. All of these complexes have been fully characterized by FTIR, 1 H-NMR, UV–vis spectroscopies and fast atom bombardment mass spectrometry (FABMS). The solid-state molecular structures of 1 and 2 have been determined by X-ray crystallography and they involve the coordination of L 1 to the {M(CO) 5 } moiety (M=Mo, W). It was found that all of these anthryl-substituted compounds are luminescent in fluid solutions at room temperature, which is attributed to the metal-perturbed anthracene emission. The emission maxima are red-shifted upon metal coordination and with the metal centers descending down the Group, suggesting some degree of electronic interactions between anthracene and the electron-withdrawing metal unit in each case.

Synthesis of 9,9-Dialkyl-4,5-diazafluorene Derivatives and Their Structure–Activity Relationships Toward Human Carcinoma Cell Lines

A homologous set of 9,9‐dialkyl‐4,5‐diazafluorene compounds were prepared by alkylation of 4,5‐diazafluorene with the appropriate alkyl bromide and under basic conditions. The structures of these simple organic compounds were confirmed by spectroscopic techniques (FTIR, NMR, and FABMS). Their biological effects toward a panel of human carcinoma cells, including Hep3B hepatocellular carcinoma, MDAMB‐231 breast carcinoma, and SKHep‐1 hepatoma cells, were investigated; a structure–activity correlation was established with respect to the length of the alkyl chain and the fluorene ring structure. The relationship between the mean potency [log(1/IC50)] and alkyl chain length was systematically studied. The results show that compounds with butyl, hexyl, and octyl chains exhibit good growth inhibitory effects toward these three human carcinoma cell lines, and the 9,9‐dihexyl‐4,5‐diazafluorene further exhibits antitumor activity in athymic nude mice Hep3B xenograft models. For the structurally related dialkylfluorenes that lack the diaza functionality, inu2005vitro cytotoxicity was not observed at clinically relevant concentrations.

Synthesis and characterisation of new oligoacetylenic silanes

Synthetic routes to a series of novel oligoacetylenic silanes with or without (hetero)aromatic bridges have been developed. The compound Me3SiCCSi(Ph)2CCSiMe3 was first prepared, which was selectively desilylated with CaCO3 in methanol at room temperature to afford the mono-protected bis(alkynyl) silane Me3SiCCSi(Ph)2CCH in moderate yield. Treatment of this mono-protected species with nBuLi, followed by silylation with Ph2SiCl2, gives a good yield of Me3SiCCSi(Ph)2CCSi(Ph)2CCSi(Ph)2CCSiMe3, with alternating silicon and acetylene units. A range of linear silicon-linked oligoalkynes containing phenylene, bithienylene and anthrylene rings, HCCRCCSi(Ph)2CCRCCH and HCCRCCSi(Ph)2CCRCCSi(Ph)2CCRCCH (Ru2006=u20061,4-phenylene, 5,5′-bithienylene or 9,10-anthrylene), were synthesised by condensation reactions of Ph2SiCl2 with the components obtained in situ from a HCCRCCH–nBuLi mixture in THF and the products were isolated by chromatography on silica. All these new compounds have been characterised by IR, 1H and 13C NMR and UV/VIS spectroscopies and mass spectrometry. The single-crystal X-ray structure of HCC(p-C6H4)CCSi(Ph)2CC(p-C6H4)CCSi(Ph)2CC(p-C6H4)CCH has been determined, showing that two silicon atoms and six acetylene units constitute the backbone of the molecule.

Synthesis, structures and properties of platinum(II) complexes of oligothiophene-functionalized ferrocenylacetylene

A series of rigid-rod alkynylferrocenyl precursors with oligothiophene (from thiophene to terthiophene) linkage units in the backbone, [(η5-C5H5)Fe(η5-C5H4)CC(C4H2S)mBr] 2a–2c, [(η5-C5H5)Fe(η5-C5H4)CC(C4H2S)mCCSiMe3] 3a–3c and [(η5-C5H5)Fe(η5-C5H4)CC(C4H2S)mCCH] 4a–4c (m n= 1–3), have been prepared in moderate to good yields. The ferrocenylacetylene complexes 4a–4c ncan be used to form a range of stable platinum(II) alkynyl and bis(alkynyl) compounds trans-[(η5-C5H5)Fe(η5-C5H4)CC(C4H2S)mCCPt(PEt3)2Ph] 5a–5c and trans-[(η5-C5H5)Fe(η5-C5H4)CC(C4H2S)mCCPt(PBu3)2CC(C4H2S)mCC(η5-C5H4)Fe(η5-C5H5)] 6a–6c (m n= 1–3). All these new compounds have been fully characterized by analytical and spectroscopic methods and the molecular structures of the bithienyl-linked ncomplexes [(η5-C5H5)Fe(η5-C5H4)CC(C4H2S)2CC(η5-C5H4)Fe(η5-C5H5)], 2b, 4b, 5b and 6b have been established by X-ray crystallography. Structural analysis of 6b confirms its rigid-rod structural motif, featuring coplanar bithienyl rings and a trans arrangement of the two bithiophene groups. An iron–iron through-space distance of ca. 32 A is observed in 6b. Although there is no significant metallocene–metallocene interaction through the alkynyl–platinum–oligothiophene bridge, a slight negative shift nof the ferrocene–ferrocenium redox potential in the platinum-containing species indicates some degree of electron delocalization into the platinum segment, in line with the results from theoretical studies. Oxidation of the thiophene units is facilitated by the presence of the platinum centre and increased conjugation in the chain.

Synthesis and Characterization of Some Metal Complexes of 4,5-Diazafluoren-9-one and their Biological Effects on Human Carcinoma Cells

Three new transition metal complexes of 4,5-diazafluoren-9-one, [(DAFO)PdCl2], [(DAFO)PtCl2], and [(DAFO)ZnCl2], were prepared in good yields by the reactions between appropriate metal chloride precursors and 4,5-diazafluoren-9-one under ambient conditions. The structures of these metal complexes were established by spectroscopic (Fourier-transform IR, NMR, and fast-atom bombardment mass spectrometry) techniques. The possible biological activity of these compounds on three human cancer cell lines including Hep3B, MDAMB-231, and SKHep-1 was investigated. The results obtained showed that both zinc- and platinum-containing compounds exhibit a similar growth inhibitory effect on these three cancer cell lines when compared with the prototypical cis-platin. In contrast, the corresponding palladium congener is virtually biologically inactive in these trials.

Synthesis, structures and optical spectroscopy of photoluminescent platinum-linked poly(silylacetylenes)

Synthetic routes to a series of novel oligomeric and polymeric platinum(II)-containing silylacetylenes have been developed. The CuI-catalyzed reaction of trans-[Pt(PEt3)2PhCl] with the alkynylsilane Ph2Si(CCH)2, in a basic medium, afforded the mononuclear trans-[Ph(Et3P)2PtCCSiPh2CCH] n(1) and the dinuclear trans-[Ph(Et3P)2PtCCSiPh2CCPt(PEt3)2Ph] n(2). Complex 1 can be utilized as a key starting material for access to the triplatinum(II) system trans-[Ph(Et3P)2PtCCSiPh2CCPt(PBu3)2CCSiPh2CCPt(PEt3)2Ph] n(3). Attempted oxidative coupling of 1 only led to the isolation of the triacetylenic species trans-[Ph(Et3P)2PtCCCCCCPt(PEt3)2Ph] n(5), involving cleavage of Si–C(alkyne) bonds. Soluble and thermally stable platinum(II) poly-yne silane polymer trans-[–Pt(PBu3)2CCSiPh2CC–]n n(4) was prepared in good yield by CuI-catalyzed polymerization of trans-[Pt(PBu3)2Cl2] and Ph2Si(CCH)2. The single-crystal X-ray structural analyses and DFT calculations were performed on 1, 2 and 5. We report the optical absorption and photoluminescence spectra of these new metal-based oligomeric and polymeric silylacetylenes and the results are compared with platinum(II) poly-ynes with purely acetylenic and (hetero)aromatic conjugated units.