72692-67-2Relevant academic research and scientific papers
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
MacDougall, J.Jeffrey,Nelson, John H.,Fultz, William C.,Burmeister, John L.,Holt, Elizabeth M.,Alcock, Nathaniel W.
, p. 75 - 83 (1982)
Steric control of the thiocyanate's 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.
Nitrogen-14 nuclear quadrupole resonance study of coordinated thiocyanate
Fultz, William C.,Burmeister, John L.,Cheng,Brown, Theodore L.
, p. 1734 - 1738 (2008/10/08)
A series of twenty palladium(II) thiocyanate complexes have been synthesized and their 14N nuclear quadrupole resonance (NQR) spectra recorded by using the recently developed technique of adiabatic demagnetization in the laboratory frame-double resonance level crossing (ADLF-drlc). A clearly definitive trend for determining the mode of coordination of the thiocyanate moiety, via its 14N nuclear quadrupole coupling constant, has been established. The field gradients at nitrogen are found to be largest in sulfur-bound thiocyanates and smallest in nitrogen-bound thiocyanates, while ionic thiocyanates have field gradients of intermediate values. The asymmetry parameter does not vary consistently with the mode of attachment but, on the average, increases in the order NCS- a lone electron pair. For coordinated thiocyanate, the occupation of a single 2p orbital is greatest for the sulfur-bound complexes. These results support the resonance forms generally accepted, based on bond angle measurements from other techniques, e.g., X-ray crystal structures. Nitrogen-14 NQR via the ADLF-drlc experiment is the most unambiguous technique to date, short of a single-crystal X-ray crystal structure analysis, for the determination of the bonding mode of diamagnetic, hydrogen-containing complexes of thiocyanate in the solid state.
