Kinetics of hindered rotation about carbon-nitrogen single bonds in some N,N,-diisopropyldithiocarbamates

Journal Article · Wed Jul 06 00:00:00 EDT 1983 · Inorg. Chem.; (United States)

DOI:https://doi.org/10.1021/ic00156a015· OSTI ID:5273018

Lindmark, A F; Fay, R C

The metal N,N-diisopropyldithiocarbamate complexes NaL, NiL/sub 2/, CoL/sub 3/, AlL/sub 3/, InL/sub 3/, and ZrL/sub 4/ (L = S/sub 2/CN(i-Pr)/sub 2/) have been prepared and characterized by IR and /sup 1/H NMR spectroscopy. Low-temperature /sup 1/H NMR spectra of these compounds exhibit two equally intense isopropyl methyl doublets and two equally intense methine septets, attributed to a ligand conformation in which the methine protons of the inequivalent isopropyl groups are located in the plane of the liqand in environments that may be labeled ''inner'' or ''outer'' with respect to the quasi-twofold axis of the ligand. Between -50 and +15/sup 0/C the methyl doublets and methine septets coalesce to a single doublet and a single septet, respectively, owing to hindered rotation about the C-N single bonds. Rate constants (s/sup -1/) at -10/sup 0/C in CH/sub 2/Cl/sub 2/ solution vary from 1400 for CoL/sub 3/ to 8.3 for NaL; E/sub a/ = 10-12 kcal/mol and ..delta..S/sup + +/ = -7 to -13 eu. The rates increase with decreasing size, increasing charge, and increasing class by character of the metal ion and with decreasing SCS angle and increasing CNC angle in the analogous N,N-diethyldithiocarbamates. These trends can be understood in terms of a metal-induced variation in the amount of steric congestion in the N(i-Pr)/sub 2/ group. The methyl ester MeSC(S)N(i-Pr)/sub 2/ exists in CH/sub 2/Cl/sub 2/ solution as a 0.58:0.42 equilibrium mixture of two conformers that have the ''outer'' methine proton cis and trans, respectively, to the SMe group. Exchange of isopropyl methyl groups among the four inequivalent sites of the two conformers has been analyzed in terms of hindered rotation about (i) the C-N single bonds and (ii) the C-N partial double bond. Kinetic data are also reported for rotation about the C-N bond in the diisobutyl derivative MeSC(S)N(i-Bu)/sub 2/.

• Research Organization: Cornell Univ., Ithaca, NY
• OSTI ID: 5273018
• Journal Information: Inorg. Chem.; (United States), Vol. 22:14
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ALUMINIUM COMPLEXES
STRUCTURAL CHEMICAL ANALYSIS
CARBAMATES
COBALT COMPLEXES
INDIUM COMPLEXES
NICKEL COMPLEXES
SODIUM COMPLEXES
ZIRCONIUM COMPLEXES
CHEMICAL BONDS
INFRARED SPECTRA
NUCLEAR MAGNETIC RESONANCE
ORGANIC SULFUR COMPOUNDS
ALKALI METAL COMPLEXES
CARBONIC ACID DERIVATIVES
CARBOXYLIC ACID SALTS
COMPLEXES
MAGNETIC RESONANCE
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
RESONANCE
SPECTRA
TRANSITION ELEMENT COMPLEXES
400301* - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)