J. Jeffrey. MacDougall

Characterization of Carlin-Type Gold Ore by Photoacoustic, Raman, and EPR Spectroscopy

Low-grade carbonaceous gold ore (0.01 to 1.8 oz/ton of gold) from the Carlin mine in Elko county, Nevada, has been characterized by a variety of analytical and spectroscopic techniques with emphasis on vibrational spectroscopy. A particular concern was determining the nature of the carbon-containing material in the ore. It was found that in addition to the anticipated carbonate, finely disseminated elemental carbon is present in amounts ranging from 0.062 to 0.43 wt. %. Contrary to previous reports, no detectable amounts of humic acid materials or organic hydrocarbons are present in any of the samples investigated.

Coordination behavior of thiocyanate in the complexes [CH3P(C6H5)2]2M(CNS)2 (M = Ni, Pd, Pt)

Abstract The complexes [CH3P(C6H5)2]2M(CNS)2 (M = Ni, Pd, Pt) have been prepared and characterized. The structures of these complexes are markedly metal ion and physical state dependent. All of the complexes are square planar. In the solid state the nickel complex is trans-L2M(NCS)2 (by crystal structure analysis), the palladium complex is trans-L2Pd(SCN)2 and the platinum complex it cis-L2(NCS)2 (both determined by infrared spectroscopy, including integrated intensity measurements). Fourier transform phosphorus nmr spectra on chloroform solutions at ambient temperature indicate that for the platinum complex, all six possible isomers are present in solution in the relative ratios: trans-L2Pt(NCS)2: trans-L2Pt(SCN)(NCS): trans-L2Pt(SCN)2: cis-L2Pt(NCS)2: cis-L2Pt(SCN)2: cis-L2Pt(SCN)(NCS): 0.38:0.57:0.38: 0.34:0.28:1, respectively. For the palladium complex, under similar conditions, all of the isomers but cis-L2Pd(SCN)(NCS) are present, with trans-L2Pd(NCS)2 and cis-L2Pd(NCS)2 predominant in a ratio of O.15:1, respectively. The relative population of cis isomers decreases in the sequence Pd > Pt > Ni, and the relative population of mixed linkage isomers decreases in the sequence Pt > Pd > Ni. The differences in the structures are discussed in light of current theories.

4-substituted quinoline N-oxide complexes of copper(II) acetate

Abstract A series of 4-substituted quinoline N-oxides (4ZQNO) and isoquinoline N-oxide (IQNO) have been found to react with copper(II) acetate to form the dimeric complexes [Cu(CH 3 (COO) 2 ·4ZQNO] 2 ·nH 2 O where Z is CH 3 O, CH 3 , H and Cl. The complexes were characterized by elemental analyses, electronic and infrared spectra and magnetic measurements. These data are all consistent with the δ-bonding model. The contributions of ligand steric effects and α- and π-bonding strengths to the magnitude of the copper-copper interaction are discussed. The isoquinoline N-oxide complex dehydrates over a period of time, resulting in crystal degradation to a powder. This is accompanied by a structural reorganization wherein the acetate groups probably change from bridging to monodentate. This results in a change in the magnetic moment from μ = 1.34 B.M. to μ = 2.00 B.M. with time.

A systematic study of steric control of the thiocyanate's bonding mode in [Pd(substituted diamine)(thiocyanate)2] and [Pd(substituted diamine)2] (SCN)2 complexes

Abstract Steric control of the thiocyanates bonding mode in Pd(II) complexes has been systematically studied by the synthesis and characterization (elemental analysis, IR (solid state and solution), molar conductance, 13C NMR and electronic spectral measurements) of 14 complexes containing bidentate substituted diamines representing a wide range of steric requirements. In the solid state, the diamines producing the least steric hindrance (1,2-diamino-2-methylpropane, 1,2-bis(methylamino)ethane, 1-amino-2-dimethylaminoethane, 2-aminomethylpyridine) were found to form ionic complexes of the type [Pd(diamine)2-(SCN)2. Diamines having intermediate steric demands (1,2-bis(dimethylamino)ethane, 1,2-bis(phenylamino)-ethane, 1-amino-2-morpholinoethane, 1-amino-2-pyrrolidinoethane, 1-amino-2-piperidinoethane) produced S-bound [Pd(diamine)(SCN)2] complexes, whereas those exhibiting the greatest steric requirements (1,2-dipiperidinoethane, 1,2-dipyrrolidinoethane, 1,3-bis(dimethylamino)propane) yielded N-bound [Pd(diamine)(NCS)2] complexes. Two diamines did not allow these trends: the sterically undemanding 1,2-diaminobenzene produced a neutral S-bound complex, as did the bulky 1,2-dimorpholinoethane. The structure of the 1,2-diamino-2-methylpropane complex was confirmed by the results of a single crystal X-ray structure determination [PdS2N6C10H24: a = 6.834(2), b = 10.304(2), c = 11.704(2) A, β = 91.59(2)°, P21/c, Z = 2], as was the structure of the [Pd(1-amino-2-pyrrolidinoethane)2] (SCN)2 complex resulting from the attempted recrystallization of [Pd(1-amino-2-pyrrolidinoethane)(SCN)2] in hot DMF [PdS2N6C14H28; a = 6.805(9), b = 16.765(31), c = 8.964(10) A, β = 111.22(9)°, P21/c, Z = 2]. In DMF solution, all of the neutral S-bound complexes were found to undergo partial or full linkage isomerization to the N-bound forms, with the exception of those containing 1,2-bis(phenylamino)ethane and 1,2-diaminobenzene.