the diketone groups and the chelating atom of the adduct. A postulated intramolecular exchange mechanism has the adduct rise above this plane and rotate about the uranyl axis to the other side.2b If this mechanism is correct, one would expect a greater activation energy for intramolecular exchange the greater the distance of the uranium above the plane of the ligands. These distances and the activation energies are listed in Table IV. There is not good agreement between the two sets of parameters.Another possible intramolecular exchange mechanism is the rotation of the /3-diketone ring about an axis perpendicular to that of the uranyl group. This would have the effect of changing the positions of two, rather than all four, of the trifluoromethyl groups. It is reasonable to suppose that the more nearly planar the /3-diketone ring the more easily it might rotate. In Table IV are listed the maximum deviations from planarity for a carbon in each of the /3-diketone rings of the adduct. There is a good correlation between these deformations and the activation energy for trifluoromethyl exchange, except for the azide adduct. In this case it is not possible to determine which of the two isomers observed in solution is isolated in the solid. If it is the more rapidly averaging isomer, which would have a lower activation energy than that reported, then the correlation is good for all the compounds. It is therefore suggested that in these adducts the exchange occurs by rotation of the 3-diketone ring. ConclusionsTwo different structural forms of the azide and fluoborate adducts coexist in sulfur dioxide solution. The higher energy form has a faster averaging for the trifluoromethyl groups in both adducts. There are two concurrent exchange mechanisms for the tetrahydrofuran and chloride adducts. The lower energy pathway is by an intermolecular displacement mechanism, and the higher energy one by an intramolecular exchange. In all the adducts the intramolecular exchange probably occurs by rotation of the 3-diketone ring.

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Outer-sphere charge-transfer (OSCT) transitions have been observed in water for a series of mixed-metal ion pairs: [Mn(CN6),Rum(NH3)5(L)]~(M = Fe, Ru, Os; L = pyridine or a substituted pyridine). After developing an appropriate thermochemical cycle it is possible to show that as expected from theory, the energies of the optical transitions vary with

An electrochemical approach to assessing the degree of electronic coupling in mixed-valence binuclear complexes is outlined. The method relies on the comparison of electrochemical potential shifts induced at both the directly and indirectly perturbed metal sites when a ligand substitution process is carried out at one site, e.g., [symmetric] ( N H~)~R U -L~~R U ( N H~)~~+ /~+ /~+ -[asymmetric] L(NH~)~RU-LI,,-R~(NH~)~~+/~+/~+, where the bridging ligandLbr is either pyrazine or 4-cyanopyridine and the perturbing ligand L is a substituted pyridine. It is found that the degree of electronic coupling in these systems is at least three times that which would be predicted based solely on spectroscopic measurements. The stabilization energy due to electron delocalization in these complexes can be accounted for with near-quantitative accuracy. It is also shown how the Mulliken analysis of the data allows for an estimation of the Wolfsberg-Helmholz constant K, which can be used in the calculation of off-diagonal matrix elements for molecular donor-acceptor interactions. (6) De la Rosa, R.; Chang, P. J.; Salaymeh, F.; Curtis, J. C. Inorg. Chem. 1985,24,4229-423 1. (7) Theuseofsubstitutbdpyridinesto'tune"thegroundandexcitcd electronic propcrticsof ruthenium amminecomplexes has been extensively employed by Ford and co-workers: (a) Malouf, G.; Ford, P. C.

Spectroscopic and electrochemical investigations have been carried out on a collection of hydrogen-bonded mixed-valence adducts of ruthenium complexes. The electron donors (H-bond acceptors) are Ru(II) cyano species and the electron acceptors (H-bond donors) are Ru(III) ethylenediamine species, and NIR spectroscopic transitions in the adducts are assigned to intervalence transfer through the hydrogen bonds holding the adducts together (HBIT). Spectroscopic studies using Job's method indicate that the adducts are 2:1 ternary aggregates of formulations such as [((trpy)(bpy)RuII(CN))2,(en)2RuIII(bpy)]5+ and [((bpy)2RuII(CN)2)2,(en)2RuIII(bpy)]3+. Voltammetric investigations show substantial repulsion of the redox waves of the parent complexes in mixtures containing both donor and acceptor. Comparison with known electronic coupling data for mixed-valence ruthenium dimers covalently bound through dithiaspiroalkane bridging ligands indicates that the electronic coupling through H bonds of this type is 65−75% as strong as through σ-covalent bonds.

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Purpose Airway protective disorders are common in Parkinson's disease (PD), yet effective methods to rehabilitate these life-threatening impairments are limited. This study examined the effects of two skill-based treatments aimed at improving swallowing and cough in a severely dysphagic person with PD: respiratory–swallow coordination training (RSCT) and voluntary cough skill training (VCST). It was hypothesized that (a) RSCT would improve respiratory–swallow coordination and swallowing safety and efficiency and (b) VCST would improve reflex and voluntary cough effectiveness. Method An 81-year-old man with midstage PD and severe dysphagia was recruited for study participation. The study utilized a multiple-baseline ABACA experimental design with a 2-month delayed retention assessment. Measures of respiratory–swallow coordination, swallowing safety and efficiency, and cough effectiveness were collected at each assessment using respiratory inductive plethysmography, flexible endoscopic evaluations of swallowing, and spirometry. Data were analyzed descriptively using baseline corrected tau and standard mean difference effect sizes ( d ). Results Large effect sizes were observed immediately following RSCT for respiratory–swallow coordination ( d = 9.17), penetration–aspiration ( d = 12.88), vallecular residue ( d = 1.75), piriform residue ( d = 4.15), and overall dysphagia severity ( d = 1.83). Large effect sizes were also observed immediately following VCST for single voluntary cough ( d = 4.30), sequential voluntary cough ( d = 3.28), and reflex cough ( d = 5.58). Improvements were maintained 2 months later for all outcome measures except single voluntary cough. Discussion This is the first study to examine the effects of RSCT and VCST in a person with PD. Robust improvements in respiratory–swallow coordination and swallowing safety and efficiency were achieved following four sessions of RSCT, and significant improvements in reflex and voluntary cough strength were seen following four sessions of VCST. Future work is needed to study these treatments in larger cohorts of people with PD.