Louis K. Peterson

The preparation and reactions of bis(pyrazolyl)phenylmethane complexes of rhodium(I)

Abstract The complexes [(LL)Rh(C 2 H 4 )Cl] x (I), [(LL)(Rh(cod)Cl) 2 ] (II), [(MeLL)Rh(C 2 H 4 ) 2 Cl] (III) and [(MeLL)Rh(cod)] + Cl − (IV) have been prepared via the reactions of the bis-(pyrazolyl)phenylmethane ligands PhCH(H 2 pz) 2 (LL; H 2 pz = pyrazolyl) and PhCH(Me 2 pz) 2 (MeLL; Me 2 pz = 3,5-dimethylpyrazolyl) with [Rh(C 2 H 4 ) 2 Cl] 2 and [Rh(cod)Cl] 2 (cod = cyclooctadiene). Complex IV reacts with NaBPh 4 to form [(MeLL)Rh(cod)] + BPh 4 − (V). III and IV reacts with carbon monoxide to give [(MeLL)Rh(CO) 2 ] + [Rh(CO) 2 Cl 2 ] − (VI). Complexes I and III give neutral solutions in methanol, while II and IV behave as 1 : 2 and 1 : 1 electrolytes, respectively. The rhodium(I) centre is typically four-coordinate in I, II, IV–VI, and five-coordinate in III. The ligands LL and MeLL show bidentate chelating behaviour in all of the above complexes, with the exception of II, where LL bridges two different Rh I moieties. Reactions with H 2 , HCl and Ph 3 P are described. Complex III functions as a homogeneous catalyst, in neutral methanolic solution, for the hydrogenation of olefin, but is ineffective for the hydrogenation of α β-unsaturated aldehydes and ketones.

Copper levels in the muscle and liver tissue of farmed chinook salmon,Oncorhynchus tshawytscha

Abstract Farmed chinook salmon, Oncorhynchus tshawytscha , were collected from pens treated with the algicide “Amercoat 675” in which the active ingredient is copper oxide, and from untreated pens, over a 3 month period (May–August 1988). The dorsal muscle and the liver of the salmon were analysed for copper by atomic absorption spectroscopy (AAS) and X-ray fluorescence spectroscopy (XRF), respectively. Results showed that the copper concentration in the muscle decreased with increasing size of the fish, while the concentration in the liver increased. There were no statistical differences in the copper levels between salmon of comparable size raised in the two types (copper-treated vs. untreated) of enclosure.

The preparation of Cr(O), Mo(O), W(O), Re(I), Rh(I), Mo(II) and Pd(II) complexes of N-diphenylphosphinopyrrole and -2,5-dimethylpyrrole

The complexes trans-[(LP)2Cr(CO)4], cis-[(LP)2Mo(CO)4], trans-[(LM)2W(CO)4], [(LM)Mo(CO)5], cis-[(LM)Re(CO)4Br], [(LP)2Mo(CO)2Br2], [(LM)2Rh(CO)Cl] and trans-[(LM)2PdCl2] (LP = N-(diphenylphosphino)pyrrole; LM = N-(diphenylphosphin-2,5-dimethylpyrrole) have been prepared. Structural assignments were based upon IR data. LP resembles Ph3P in coordinating ability, while LM is a poorer ligand. The successive replacement of Ph in Ph3P by the pyrrolyl moiety causes a decrease in the donor properties of the phosphorus centre.

A qualitative study of the reactions of 3,5-dimethylpyrazolyldiphenylphosphine with tetracarbonyl complexes of molybdenum(0) and tungsten(0)

The reactions of diphenyl(3,5-dimethylpyrazolyl)- phosphine (LL) with [(nbd)M(CO)4] (nbd = norbornadiene, M = Mo, W) and with [(CH3CN)2W(CO)4] under mild conditions proceed in a stepwise fashion to yield a mixture of products in equilibrium. The four-membered metallocyclic species (LL)M(CO)4 and the phosphorus-coordinated complex cis-[LL)2 M(CO)4] are formed in competition, being favoured by 1:1 and >2:1 reaction stoichiometries respectively.

Reactions of five-coordinate molybdenum(0) and Tungsten(0) complexes [PhP(Me2pz)2M(CO)3]with small molecules

Abstract The coordinatively unsaturated species [PhP(Me 2 pz) 2 M(CO) 3 ] (Me 2 pz = 3,5-dimethylpyrazolyl; M = Mo, I; M = W, II) react reversibly with CO, and irreversibly with H 2 , C 2 H 4 , P(OMe) 3 and PF 3 , but not with N 2 and Ph 3 P. The tricarbonyl/tetracarbonyl interconversion (I, II) + CO ⇄ [PhP(Me 2 pz) 2 - M(CO) 4 ] (III, M = Mo; IV; M = W) involves a novel structural interchange between the pseudo C 3v , phosphorus-free, six-membered [P(NN) 2 M] boat metallocyclic form of I and II, and the pseudo C 2v , phosphorus-coordinated, four-membered [ PNNM ] metallocyclic structures of III and IV. The reaction of 1 with PF 3 gives [PhP(Me 2 pz) 2 Mo(PF 3 ) 2 ] (V), in which the pyrazolylphosphine ligand again defines a four-membered [ PNNM o] chelate structure. A trans -dicarbonyl, cis-( bis -trifluorophosphine) arrangement is indicated.

Synthesis and reactions of [M(CO)4(Ph2PSiMe3)X] complexes (M = Mn, Re; X = Halogen)

The silylphosphine ligand Ph2PSiMe3 reacts readily with a slurry of [Re(CO)5X] (X  Cl, Br) in polar and in non-polar solvents to yield soluble cis-[Re(CO)4- (Ph2PSiMe3)X] (Ia, X  Cl;Ib, X  Br) via CO substitution. Compound I is readily hydrolyzed by water or silica gel to cis-[Re(CO)4(Ph2PH)X]. Compound Ib reacts with [Re(CO)5Br] to yield [Re2(CO)8(μ-PPh2)- (μ-Br)] (II), and with [Mn(CO)5Br] to yield [MnRe- (CO)8(μ-PPh2)(μ-Br)] (III). The reaction of Ph2PSiMe3 with [Mn(CO)5X] (X=Cl,Br,I) is highly dependent upon reaction conditions.In polar and in non-polar solvents, an excess of ligand gives mainly cis-[Mn(CO)4(Ph2PSiMe3)X] (IVa, X  Cl;IVb, X  Br;IVc, X I). With ligand: [Mn(CO)5X] reacting ratios in the range 0.5–1.0:1, the products from the three respective halomanganese complexes in THF were: (a) mainly [Mn2(CO)8(μ- PPh2)(μ-Cl) (Va); (b) both [Mn(CO)4(Ph2PSiMe3)Br] and [Mn2(CO)8(μ-PPh2)(μ-Br)] (Vb); and (c) exclusively [Mn(CO)4(Ph2PSiMe3)I]. The compounds IVa-c are stable in solution at ambient temperatures and are readily hydrolyzed by water or methanol to [Mn(CO)4(Ph2PH)X]. Compound IVb reacts at room temperature with [Mn(CO)5Cl] to yield only [Mn2- (CO)8(μ-PPh2)(μ-Br)] (Vb); compound IVc reacts in hot toluene with [Mn(CO)5Cl] to yield mainly [Mn2(CO)8(μ-PPh2)(μ-I)] (Vc), together with a small amount of the chloro-bridged analog. The dinuclear species II, III and Va-c appear to be formed mainly via an intermolecular elimination of Me3SiX from the appropriate [M(CO)4(Ph2PSiMe3)X] and metalpentacarbonylhalide (chloride or bromide) complexes.

Preferential displacement of fluorophosphine ligands from fluorophosphinetungstencarbonyl complexes by reaction with trimethylamine oxide

The photolysis of [W(CO)4dppe] in toluene in the presence of a large excess of PF3, using a medium pressure mercury lamp, gives [W(PF3)4dppe] (I). The thermal reaction of solutions of cis-[W(CO)4,(Ph3P)(CH3CN)] with fluorophosphine ligands L gives cis-[W(CO)4(Ph3P)L] (L=PF3 (II), Me2NPF2 (III), MeN(PF2)2 (IV)). Compounds I–IV were characterized by IR, mass and NMR spectroscopy. They react with Me3NO in acetonitrile, with loss of the fluorophosphine ligand. The CO ligands in II–IV are not attacked by the amine oxide.

The Synthesis and Characterization of Rhenium(o)-Nitrile Complexes Re2(CO)9,8(RCN)1,2

Abstract The complexes Re2(CO)9, 8(RCN), 2 (R = CH3, CH3CH2, CH3CH2CH2, (CH3)2CH) were prepared via the amine-oxide assisted reaction of Re2(CO)10 with the appropriate organonitrile. The complexes were characterized by i.r., 1H and 13C n.m.r. and mass spectroscopy. The RCN ligands preferentially occupy equatorial sites, although some minor axial-substitution occurs with the more bulky ligands. Unlike species such asOs3(CO)11,10(CH3CN)1,2, the nitrile ligands of Re2(CO)9,8(RCN)1,2 are not displaced by nucleophiles under mild conditions.

Reactivity of [Cp∗Re(η3-C3H5)(CO)2][BF4] towards oxygen, sulfur, nitrogen and carbon nucleophiles

Abstract The nucleophilic addition of oxygen, sulfur, nitrogen and carbon nucleophiles to [Cp∗Re(η3-C3H5)(CO)2][BF4] (1) has been investigated. In all cases, addition of the nucleophile to the allyl ligand in 1 was observed to result, giving the substituted propene complexes with general formula Cp∗Re(CO)2(η2-C3H5R) (RCH3CO2, C2H5S, C6H5S, NH2, CHMe2 and C6H5) and [Cp∗Re(CO)2]2(η2;η2-C3H5S(CH2)3SC3H5). No product of attack at the central carbon was observed for any of the nucleophiles. In the cases where the nucleophile was NH2− or C6H5Li, nucleophilic addition occurred either at the η3-allyl or at a CO ligand. At low temperature (−78-0°C) the CO was attacked and complexes with general formula Cp∗Re(η3-C3H5)(CO)(COR) (R  NH2 and C6H5) were produced. When R is C6H5, the product was stable and was observed along with the substituted propene complex in solution, but when NH2− was used, the carbamoyl complex converted completely to the substituted propene complex at room temperature. A by-product of the method used to synthesize Cp∗Re(η2-C3H5SC6H5)(CO)2 was a small amount of Cp∗Re(η3-C3H5)(CO)(O2CSC6H5) (7). The X-ray crystal structure of 7 has been determined.

Cobalt(II) and zinc(II) complexes of 1,1,5,5,-tetramethylcarbohydrazide

Abstract 1,1,5,5,-Tetramethylcarbohydrazide (Me2NNH)2CO(tmc) was synthesized via the thermal decomposition of the carbamate Me2NNHC(O)OSiMe3. The complexes Co(tmc)Cl2(III), Co(tmc)2Cl2(IV), Zn(tmc)Cl2(V) and Zn(tmc)2Cl2(VI) were prepared. These compounds are non-electrolytes in solution in acetone and nitromethane. The complexes III and V have pseudo tetrahedral structures in the solid state and in solution in acetone, in which they are monomeric. The most likely solid state structure for the M(tmc)2Cl2 complexes IV and VI is octahedral. In solution, however, complexes IV and VI are extensively dissociated, via loss of one tmc ligand, giving equilibrium mixtures containing the four-coordinate complexes III and V, respectively. In all four complexes, the tmc ligand chelates to the metal centre via the carbonyl oxygen and one of the terminal dimethylamino groups. The ligand in Zn(tmc)Cl2 is non-fluxional. Exchange among tmc ligands in solutions of Zn(tmc)2Cl2(VI) is rapid on the nmr time scale at temperatures above O °C.