Computational Study on the Nature of Bonding between Silver Ions and Nitrogen Ligands.

In this paper, the nature of silver ion-nitrogen atom bonding in the complexation with ammonia, azomethine, pyridine, and hydrogen cyanide from one to four coordinations is studied at the B97-1 level of density functional theory. The results indicate that the two-coordinated complex of the silver ion with different nitrogen ligands representing sp, sp2, and sp3 orbital hybridizations is the most stable form having the shortest Ag+-N bond distance, highest vibrational frequencies, largest bond order, and favorable Gibbs free energy of formation. Natural bond orbital analyses further show that σ-donation from the nitrogen lone pair to the silver empty 5s orbital is dominant in the dative metal-ligand bonding character with N-sp3 having the largest contribution among the different N atomic orbital hybridizations. Natural energy decomposition analyses further show that the two-coordinated complexes have enhanced electrostatic interaction and charge transfer energies over other coordination types leading them to be more stable. For this reason, the two-coordinated complexes would be a better representation for studying bonding and interaction in silver ion complexes.

Psychiatric use of unscheduled medications in the Pennsylvania state hospital system: effects of discontinuing the use of P.R.N. orders.

The objective of this prospective study was to assess patient exposure to the psychiatric use of unscheduled medications at all nine Pennsylvania state hospitals and to unify practice guidelines in this regard. In August 2004, a decision was made to discontinue the use of p.r.n. orders for psychiatric indications. All unscheduled medications, (p.r.n. and STAT physician's order) administered for psychiatric indications were entered into a uniform database. A total of 46,913 unscheduled medications were administered to people served in the hospital system throughout this 15 month study. During March 2004, 87.7 unscheduled medications per 1,000 days-of-care were administered in the hospital system. During the last month of this study, May 2005, this rate had decreased to 17 per 1,000 days-of-care. Many hospital safety measures significantly improved as a result of this change. Cessation of p.r.n. medication use for psychiatric indications has significantly decreased patient exposure to unnecessary psychotropic medications and has resulted in a safer hospital system.