Manfred Steimann

Chemical properties and cytotoxic activity of complexes of platinum(II) and palladium(II) containing dmso and various anions; synthesis and structural characterization of [Pt(dmso)2{O2(CO)2CCH2CH2CH2}]

Treatment of cis-[Pt(dmso)2Cl2] with 2 mol of KBr or KI leads to the formation of the analogous dibromide or diiodide complexes. Treatment of [M(dmso)2Cl2] [M = Pt (cis-) or Pd (trans-)] with AgNO3 (2 mol) in H2O followed by 1mol of potassium oxalate, maleate, cyclobutane dicarboxylate (CBDC), malonate or 2mol of potassium cyclohexane carboxylate or pivalate leads to the formation of the corresponding PtII and PdII carboxylate complexes. The single crystal X-ray structure determination of [Pt(dmso)2(CBDC)] has been discussed and compared with data on other related complexes. The in vitro cytotoxic activity of some of these complexes against eight tumour cell lines has been examined using the MTT-colorimetric assay.

Substrate activation by the Wilkinson analogous complex containing η2-chelated and η1 P-bonded (methoxyethyl)dicyclohexylphosphine as a hemilabile ligand

Abstract In the presence of a variety of small molecules the pseudo 14-electron rhodium complex -chelated Cy 2 PCH 2 CH 2 OCH 3 ligand; P ∼ O = η 1 ( P )-coordinated) is shown to undergo a facile cleavage of its intramolecular ether moiety. The reaction of 1 with ethene, diphenylacetylene and carbon disulfide results in the irreversible coordination of the corresponding molecule to the metal yielding the complexes ClRh(C 2 H 4 )(P ∼ O) 2 ( 2 ), ClRh(PhC≡CPh)(P ∼ O) 2 ( 3 ), ClRhCS 2 (P ∼ O) 2 ( 4 ), and ClRhCS(P ∼ O) 2 ( 5 ). All compounds are obtained in excnt yields under very mild conditions. The structures of 4 and 5 were determined by single-crystal X-ray diffraction. The oxidative addition of HCl to the starting material 1 leads to the monochelated octahedrally coordinated complex ( 6 ). Complex 6 exhibits fluxional behavior on the 31 P NMR time scale. Line-shape analysis of variable temperature 31 P{ 1 H} NMR spectra of 6 affords the Eyring parameters ΔH ± = 42.3kJ mol −1 and ΔS ± = −63.7 J mol −1 K −1 , indicating an intramolecular exchange mechanism. The RhH bond in 6 is able to insert ethene to give the ethylrhodium(III) complex Cl 2 RhC 2 H 5 ( P ∼ O ) 2 ( 7 ) . Subsequently, there follows a fast σ π rearrangement to the complex Cl 2 Rh( η 2 -C 2 H 4 )(H)(P ∼ O) 2 ( 8 ) which undergoes a slow π σ transformation to the monochelated product ( 9 ).

cis,cis-1,3,5-Tris(diphenylphosphino)cyclohexane (tdppcy). A new tripodal phosphine that forms metal complexes with adamantane-type structures. rystal structure of Ir(tdppcy)Cl3

Abstract The novel tridentate phosphine cis , cis -1,3,5-tris(diphenylphosphino)cyclohexane (tdppcy) ( 3 ) has been synthesized. Treatment of tdppcy with Mo(C 7 H 8 )(CO) 3 and Ir(PPh 3 ) 2 (CO)Cl yields octahedral Mo(tdppcy)(CO) 3 ( 4 ) and trigonal-bipyramidal Ir(tdppcy)(CO)Cl ( 5 ), respectively. Compound 5 is transformed into either Ir(tdppcy)(CO)H ( 6 ) or Ir(tdppcy)(CO)(H) 2 + ( 7 ) by treatment with NaBH 4 in refluxing THF. Complex 5 can be oxidized by dichloromethane or Cl 2 to the trichloro complex Ir(tdppcy)Cl 3 ( 8 ), which can be converted into the dihydride Ir(tdppcy)(H) 2 Cl ( 9 ) by treatment with NaBH 4 in THF. The dynamic behavior of the highly fluxional pentacoordinate complexes 5 and 6 has been studied by VT 31 P{ 1 H} NMR spectroscopy. An X-ray diffraction study has been carried out on 8 ·3CH 2 Cl 2 .

VINAMIDIN-CHELATE DES ALUMINIUMS UND GALLIUMS

Die Vinamidin-Komplexe C5H7R2AlCl2N2 (8) und C5H7R2Cl2GaN2 (9) (R = Me, iPr, tBu) des Aluminiums und Galliums werden durch Umsetzung der entsprechenden Vinamidine mit ECl3 (E = Al, Ga) in masigen Ausbeuten erhalten. Kristallstrukturanalysen von 8 a, 8 b, 9 a und 9 c zeigen einen geringen Einflus der Alkylsubstituenten auf die Struktur der Sechsringe. Ab initio-Berechnungen ergeben das Vorliegen polarer Al–N- und Ga–N-Bindungen ohne signifikante π-Wechselwirkungen. Die berechneten 13C- und 27Al-NMR-Verschiebungen werden angegeben. Vinamidine Chelates of Aluminium and Gallium The vinamidine aluminum and gallium complexes C5H7R2AlCl2N2 (8) and C5H7R2Cl2GaN2 (9) (R = Me, iPr, tBu) are obtained from the corresponding vinamidines and ECl3 (E = Al, Ga) in moderate yields. Crystal structure analyses of 8 a, 8 b, 9 a and 9 c reveal a minor influence of the alkyl subtituents on the structure of the six membered rings. Ab initio calculations demonstrate polar Al–N and Ga–N bonds without significant π-interaction. The calculated 13C- and 27Al-NMR shifts are reported.

PALLADIUM(II) COMPLEXES WITH HEMILABILE ETHERDIPHOS LIGANDS IN THE ALTERNATING COPOLYMERIZATION OF CARBON MONOXIDE WITH OLEFINS

Abstract The potentially hexadentate diphos ligands (ROCH 2 CH 2 ) 2 P(CH 2 ) 3 P(CH 2 CH 2 OR) 2 ( 1a-d ) (R=Et ( a ), n -Bu ( b ), t -Bu ( c ), Cy ( d )) are accessible by photochemically induced hydrophosphination of the vinyl ethers CH 2 CHOR with the diprimary phosphine H 2 P(CH 2 ) 3 PH 2 . Treatment of 1a–d with (PhCN) 2 PdCl 2 in CH 2 Cl 2 leads to the dichlorodiphospalladium(II) complexes 2a–d , from which the dicationic palladium(II) complexes 3a–d were obtained by abstraction of the chlorides with AgBF 4 in CH 2 Cl 2 . In 3a–d the etherdiphos ligands are coordinated in a η 4 (O,P;O′,P′) fashion. A rapid chemical exchange between the η 2 -P ∩ O chelated and the η 1 -P coordinated part of the ligands in 3a–d was demonstrated by means of temperature-dependent 13 C{ 1 H} NMR spectroscopy. Both PdO bonds in 3a–d are easily cleaved by polar solvents such as acetonitrile and water resulting in the formation of the adducts 3b  · 2CH 3 CN, 3c  · H 2 O, and 3c  · 2H 2 O. The molecular structures of 2a and 3c  · H 2 O were determined by single crystal X-ray diffraction methods. Under a total pressure of 60 bar ethene/CO and propene/CO, respectively, 3a-d are highly active catalysts in the copolymerization of olefins with carbon monoxide. GPC measurements revealed high molecular weights of these polyketones.

ZUR OXIDATION VON 2-SELENOIMIDAZOLINEN MIT IOD1

Abstract The stepwise oxidation of 2-selenoimidazolines 1 (ImSe; Im = 1,3-dihydro-1,3,4,5-tetraalkyl-2H-imi-dazol-2-ylidene) leads to a series of carbene stabilised selenium iodine compounds whose composition depend from the stoichiometry and the substituents at the nitrogen atoms. No diselenides or selenium(IV) compounds have been detected. The X-ray structures of the compounds [ImSeSelm]2+ (3c), (ImSel2)2I2 (5c) and (ImSel)I3 (6b) are reported.

Vinamidin-stabilisierte Alane

Die Alan-Komplexe (C5H7N2R2)AlH2 (2) (R = Me, iPr, Ph) werden durch Umsetzung der Vinamidine C5H8N2R2 (1) mit Me3N · AlH3 als reaktive Feststoffe in guten Ausbeuten erhalten. Ein Uberschus der Hydridkomponente bewirkt die Bildung perhydrierter Ringsysteme, von denen {(C11H24N2)Al2H4}2 (6) im praparativen Masstab hergestellt werden konnte. Die Kristallstrukturen von (C5H7N2Me2)AlH2 (2 a) und (C5H7N2iPr2)AlH2 (2 b) zeigen einen angenahert planaren Ringaufbau. In 6 sind zwei Fragmente (C11H24N2)Al2H4 durch Wasserstoffbrucken unter Bildung eines zentralen planaren Al2H2-Vierrings verknupft. Vinamidine Stabilised Alanes The alane complexes (C5H7N2R2)AlH2 (2) (R = Me, iPr, Ph) are obtained from the vinamidines C5H8N2R2 (1) and Me3N · AlH3 as reactive solids in good yields. Excess hydride reagent affords the formation of perhydrogenated ring systems from which {(C11H24N2)Al2H4}2 (6) could be prepared in a preparative scale. The X-ray structures of (C5H7N2Me2)AlH2 (2 a) and (C5H7N2iPr2)AlH2 (2 b) exhibit the expected near planar ring geometries. In 6, two units of (C11H24N2)Al2H4 (5) are connected via hydrogen bridges to form a central planar Al2H2 core.

HETEROCYCLEN ALS LIGANDEN XXII. 2-CHALKOGENOIMIDAZOLINE ALS LIGANDEN IN PENTACARBONYLMETALL-KOMPLEXEN

Abstract The chalcogenoimidazoline complexes N—CMe—CMe—NR—C=X·M(CO)3 (VIII-XI; R = Me, iso-Pr; X = S, Se, Te; M = Cr, Mo, W) are obtained from the metal hexacarbonyls (M = Cr, Mo, W) and the chalcogenoimidazolines IV-VII. In these complexes the chalcogeno ligands exhibit strong donor properties according to the sequence Te > Se > S which is demonstrated by n. m. r. and i. r. data. The X-ray structures of N(iso-Pr)—CMe—CMe—N(iso-Pr)—C=X·Cr(CO)3 (X = S; Se; VIIIa, IXa) are reported.

Inclusion of Copper(I) into a Novel Bipyridine-Containing Tetraphosphadiplatinacyclophane

The 5,5′-bis(hydroxyalkyl)-2,2′-bipyridines 4a–c (Scheme 1) were prepared either in one step (4b, 4c) or in four steps (4a) starting with 5,5′-dimethyl-2,2′-bipyridine in each case. Reaction of 4a–c with mesyl chloride afforded the bis(mesylates) [–C5H3N–(CH2)n–CH2–OSO2Me]25a–c [n = 1 (a), 2 (b), 3 (c)], which could easily be transformed into the diphosphanes 6a–c by reaction with LiPPh2. Treatment of 6c, 6b with Cl2Pt(NCPh)2 and (RC6H4)2Pt(COD) according to the high-dilution method resulted in the formation of the tetraphosphadiplatinacyclophanes [–C5H3N–(CH2)4–PPh2PtCl2PPh2–(CH2)4–C5H3N–]2 (7c) and [–C5H3N–(CH2)3–PPh2Pt(C6H4R)2PPh2–(CH2)3–C5H3N–]2 (8b, 9b) (8b: R = H, 9b: R = tBu), respectively (Scheme 2). The molecular structures of 8b and 9b were elucidated by X-ray structural analyses. The noncoordinated bipyridine moieties in 8b were employed to encapsulate copper(I) to give the host/guest complex 10b (Scheme 3), which was investigated by FAB-MS, NMR spectroscopy, and cyclovoltammetry. 10b exhibited a quasi-reversible oxidation at E1/2 = –0.31 V and an electrodeposition-redissolution redox system at E1/2 = –0.79 V, owing to the formation of copper at the surface of the working electrode.

Das verhalten des Bis(chelat) rhodium-Komplexes [Rh(P O2][BPh4] gegenüber H2, O2 und CH3I

Abstract In a reversible way the bis(chelate)rhodium complex [Rh( P O )2][BPh4] (1) [ P O : η2-O,P chelated (C6H11)2PCH2CH2OCH3 ligand) reacts with hydrogen to form the unstable dihydridorhodium complex [RhH2( P O )][BPh4] (2). The dioxygenrhodium complex [RhO2( P O )2][BPH4] (3) is obtained straightforwardly by treating 1 with oxygen. Complex 3 crystallizes in the monoclinic space group P21/c with Z = 4, as determined by an X-ray diffraction study. Upon the oxidative addition of CH3I (13 CH3I) to 1 the methylrhodium complex [RhCH3I( P O )2][BPh4] (4, 4′) is generated with cis-oriented phosphorus atoms.