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Here we report the first evidence of Pt(II) interaction with Amadori compound [N-(1-deoxy- d -Fructos-1-yl)glycine (Fru-Hgly)]. The 1H and 195Pt NMR results show that complexation of Pt(II) by Fru-Hgly is strongly dependent on pH and reaction molar ratio. In 1/1 Pt/Fru-Hgly molar ratio, at acidic pH, the first coordination site is the carboxylic oxygen, while at physiological pH the anchoring group is the aminic one, in both cases the system slowly evolves towards an N,O chelating mode. In 1/2 Pt/Fru-Hgly molar ratio the only coordination site is nitrogen atom while the carboxylic oxygen is not involved in metal coordination.

The silver(I) complexes of 2,2′,3,3′-tetrahydro-4,4′-dithia-1,1′-binaphthylidene (ttp) having a nine-member SAgS chelating ring, [Ag(ttp)(ClO4)]n (1) and [Ag2(ttp)2(CF3SO3)2]n (2), have been synthesized and characterized by single-crystal X-ray diffraction. The ttp is found to offer a potential coordination site for complexation, which can be utilized to generate an interesting array of silver(I) complexes with a one-dimensional chain and a chiral chain.

The preparation and X-ray structure analyses of the compounds [{Li(dioxane)2.5TaCl4S}n]·n/2 dioxane (1) and [{Li2(dioxane)3Cl}n][TaCl6]n (2) are described. The title compounds were isolated from a refluxed solution of TaCl5 and Li2S in dioxane/CH3CN. The compounds both crystallize in the monoclinic space group C2/c and contain a network of dioxane bridged Li+ cations. In 1, the polymeric network is further extended by TaCl4S units. The sixth coordination site of the central metal in these TaCl4S units is occupied by an O-atom of one of the Li coordinating dioxane molecules. In contrast, the [TaCl6]− complex anion in 2 is isolated within a three-dimensional LiCldioxane network.

The synthesis and full characterization of the functionalized complexes 3a–c [(dppe)Cp*Fe(CC–L)] (L=4-Py, 3-Py, 2-Py; dppe=1,2-bis(diphenylphosphino)–ethane; Cp*=pentamethylcyclopentadienyl) are reported. These electroactive compounds, stable under two redox states, behave as typical pyridyl ligands towards simple metal precursors of tungsten, palladium or platinum complexes. With (THF)W(CO)5 bi-metallic iron–tungsten complexes [(dppe)Cp*Fe(CC–Py)W(CO)5] (5a–b) were isolated. After chemical oxidation their corresponding [(dppe)Cp*Fe(CC–Py)W(CO)5][PF6] (5a–b+) salts were isolated and characterized as well. With the palladium(II) and platinum(II) dichloride (PhCN)2MCl2 precursors, neutral, mono- and dicationic trimetallic complexes of the type {[(dppe)Cp*Fe(CC-4-Py)]2MCl2}[PF6]n (M=Pd: 8a, Pt: 10a; n=0, 1, 2) were similarly isolated and studied. The mixed valence states (n=1; MV) exhibit class-I properties.

Reaction of [W(CPh)Cl(CO)(PMe3)3] (1), with NaNC4H4, NaNC8H6, NaOC6H5 and NaSR (R = CMe3, C6H11) in THF afford the alkylidyne tungsten complexes [W(CPh)X(CO)(PMe3)3] (2a−e), containing pyrrolide, indolide, phenoxide and alkylsulfide ligands, X, respectively. The π donor ligands X occupy the coordination site trans to the alkylidyne ligand. The anionic complexes [NEt4][W(CPh)X2(CO)(PMe3)2] ( ( 3a ) X = NC 4 H 4 ), (( 3a ) X = NC 8 H 6 ), form upon reaction of 1 with 2 equiv. of NaNC4H4 and NaNC8H6 in THF, followed by metathesis with NEt4Cl in CH2Cl2. Reaction of 1 with the sodium salt of pyrrole-2-carboxaldehydemethylimine affords [W(CPh(NC4H3-CHNMe-2)(CO)(PMe3)2] (4). The solid state structures of complexes 2a and 2e were determined by X-ray crystallography. Complex 2d reacts in THF solution with carbon monoxide to afford cis-[W(CPh)(SCMe3)(CO)2(PMe3)2] (6). In contrast, the analogous bromo complexes [W(CPh)Br(CO)(PMe3)3] (7) gives under the same conditions an equilibrium mixture of 7 and trans-[W(CPh)Br(CO)2(PMe3)2].

Ten novel [Cp ∗ Ru(η 6 -monosubstituted naphthalene) + O 3 SCF 3 − complexes were synthesized and characterized by 1 H, 13 C and 1 H{ 1 H}-COSY NMR spectrometry. All complexes containing electron-withdrawing substituents formed products with Cp ∗ Ru + moeity coordinated on the unsubstituted ring. In [Cp ∗ Ru(η 6 -1-naphthalamine)] + O 3 SCF 3 − , ruthenium is coordinated on the substituted ring due to the electron-donating properties of the NH 2 group. However, the methoxy and N , N -dimethylamine derivatives, despite the electron-donating properties of the substituents, coordinate the ruthenium atom on the unsubstituted ring due to steric hindrance around the substituted ring. Methylnaphthalene and hydroxynaphthalene products were formed as mixtures of coordination isomers.

Chelate (allyloxy)carbene complexes [F e(C 5 H 5 )(CO){η 2 -C(OCH 2 CHC HPh)C6H4-o-X}][OTf] (4a–b) (a, X=OMe; b, X=Cl) are readily accessible from methoxycarbene complexes 2 and 3 containing a hemilabile or labile ligand. The facile coordination of the alkenyl group, due to the presence of a potential vacant coordination site, allows the selective formation of 4.

The reactions of titanium(IV) halogen compounds with the monoalkali and dialkali metal salts of L (+)-ascorbic acid and 5,6-O-isopropylidene- L -ascorbic acid, respectively, in EtOH or THF as solvent, generally result in the formation of complexes of the appropriate dianions. Whereas the ascorbate dianion exclusively forms an ate-complex, this is not observed in the case of the 5,6,O-isopropylidene- L -ascorbate dianion. The results of our spectroscopic studies show the ene-diolate group to be the coordination site for both of the dianions. However, for the 5,6-O-isopropylidene- L -ascorbate dianion an additional weak interaction between one of the O atoms of its dioxolane ring and Ti(IV) cannot be excluded.

The new nickel(II) complexes [Ni(pqr-cy)(NCS)2], [Ni(pqr-cy)Cl]ClO4, and Ni2(pqr-cy)3(ClO4)4·nH2O (n = 4 or 5) have been prepared, where pqr-cy is a triazacycloalkane, NH(CH2)pNH(CH2)qNH(CH2)r (p,q = 2,3; r = 2–6). The isothiocyanato complexes are six-coordinate, NCS-bridged octahedral when t (= p + q + r) is small (t≦9). but they are five-coordinate when t is large (t≧9). The five-coordination is peculiar and its origin is attributable to blocking of a coordination site by the backbone polymethylene groups of the pqr-cy ligands. Only the ligands with t=9 and 10 form the chloro complexes, which are Cl-bridged dimers and are also five-coordinate because of the same steric hindrance. It is worth noting that these five-coordinate nicke(II) complexes are isolated from aqueous solutions. The 2:3 perchlorate complexes are octahedral and available only for the ligands with t=9.

The four methyl and acetyl complexes In(CO)(L)FeR (L = CO, PPH3; R = CH3, COCH3) have been synthesized and characterized as η5-indenyl (In) complexes. These were prepared in an attempt at using the indenyl ligand to generate a vacant coordination site, through its η5/η3 tautomerization, and hence promote hydrogenation of the methyl or acetyl ligand. These complexes, however, remain inert towards H2 under generally mild conditions: to 50 °C/1200 psig H2 in 1,2-dichloroethane solution. When the temperature is raised to 100 °C these complexes degrade, with no evidence for acetaldehyde/ethanol production.

A study of the stereochemistry of the ‘carbonyl insertion’ reactions: [IrCl 2 Et(CO) 2 L]+L′[IrCl 2 (COEt)(CO)LL′] shows that the rate-determining step involves the combination of ethyl and carbonyl ligands to give a five-coordinate intermediate, probably of square-pyramidal geometry, with the propionyl group in the apical position. The combination is a symmetrical process for which the two terms ‘carbonyl insertion’ and ‘alkyl migration’ are equally misleading. Subsequent attack by the incoming ligand L′ occurs at the vacant octahedral coordination site trans to the propionyl group. That the stereochemistry of the products is a direct result of the mechanism of the reactions is shown by the subsequent rearrangement of the products to a more thermodynamically stable isomer.