Mononuclear temperature variable

A further report dealt with the synthesis, variable temperature magnetic susceptibility measurements, and crystal structure determination at various temperatures (115, 136, 140, 150 and 231 K space group P-1) of [Fe(isoxa-zole)6][Fe(isoxazole)4(H20)2](BF4)4 [73]. The molecular structure of this well-defined double salt consists of two mononuclear Fe(II) dications,... 

Oxidative addition of hydrogen to mononuclear Cp Ru-diborolyl complexes formed the dihydride species 24, which could not be isolated, and readily lose H2 in vacuum 30 detailed variable-temperature NMR studies were unable to distinguish between the possible classical Ru(H)2 and non-classical Ru(H2) structures. Acetonitrile, CO, and other electron donors add similarly and in some cases reversibly, leading to bent structures such as 25.29,30... 

Spin and oxidation states of mononuclear iron-porphyrin systems may be assigned directly from magnetic susceptibility measurements and indirectly from Mossbauer spectroscopy. Variable temperature susceptibility measurements are particularly useful for detecting dinuclear systems that share at least one ligand in common if there is antiferromagnetic (or ferromagnetic) coupling of the electron spin of one metal center with that of a second. 

For peripheral blood mononuclear cells, which are components of the immune system (B cells, T cells and granulocytes), saturable kinetics of riboflavin uptake were proved (Km = 955 nM). Absorption was reduced by the addition of, among others, lumichrome and dinitrophenol. The transport was temperature dependent and sodium independent. During proliferation of these cells, uptake of the vitamin increased four times, although the transporter affinity and their number per cells remained unchanged. This suggested that accumulation of riboflavin in the cells is associated with variable cellular volume (osmolarity of environment) (Zempleni and Mock 2000) (Tables 36.1-36.4). 

Tris(amido)phosphines 40-43 react with Fc2(CO)9 to give mononuclear iron carbonyl complexes Fe(CO)4(PR3). IR data collected from these complexes, combined with data from similar complexes, revealed the TT-acidity of the phosphines to be 41 w 40 > 43 > P(OPh>3 >42 > PPh3 > P(NMe2)3- Variable-temperature NMR on the Fe(GO)4 complexes of 41-43 showed rapid exchange of axial and equatorial carbonyls from —80 to 20 °C, while complex 40 showed slow axial-equatorial carbonyl exchange even at room temperature, attributed to the steric bulk and rigidity of the ligand. 

CusaneUi A, Prey U, Richens DT, Merbach AE. The slowest water exchange at a homoleptic mononuclear metal center variable-temperature and variable-pressure NMR study on [Ir(H20)6]. Chem Soc. 1996 118 5265-5271. 

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