Reactions of nitroplatinum complexes. 1. 15N and 195Pt NMR spectra of platinum(II) nitrite complexes

15N and 195Pt NMR spectra have been used to characterize the products of reaction of Pt(15NO2)42- with sulfamic acid, Pt(15N-O2)3(H2O)- and cis-Pt(15NO2)2(H2O)2, and the hydroxo complexes Pt(15NO2)3(OH)2- and cis-Pt(NO2)2(OH)2 2- derived from them by deprotonation. At intermediate pH values, the dinitro complexes rapidly form the hydroxo-bridged compounds [{Pt-(15NO2)2(μ-OH)}n] 1- (n = 2, 3). The acid dissociation constant for Pt(15NO2)3(H2O)- (pKa 5.32) was determined from the variation with pH of δN for nitro ligands cis to water/hydroxide. 15N and 195Pt NMR parameters were obtained for the series Pt(15NO2)3Zm-. The changes in these parameters as Z was changed correlated with those in the series Pt(15NH3)3Zn+. δN and J(Pt-N) values are much more sensitive to change in the ligand Z for the nitro ligand trans to Z than for that cis to Z

Synthesis of dimethylplatinum(IV) compounds, [{PtMe2X2}n] [{PtMe2XY}n], and, in solution, fac-[PtMe2X(H2O)3]+, where X and Y are anionic ligands

Oxidative addition of X (X = Cl, Br, I) to cis-[PtMeL] (L = pyridine, py, or L = N,N,N′,N′-tetramethylethylenediamine (tmen) gave [PtMeXL]. For X = Br, I, treatment with aqueous HClO gave insoluble [{PtMeX}], but for X = Cl, [PtMeCl(HO)] remained in solution, with [{PtMeCl}] depositing only from concentrated solution. [PtMeL] (L = py, 1/2(tmen)) with water gave [PtMe(OH)L], which, on treatment with HClO gave cis-[PtMe(HO)](ClO) in solution. Water also reacted with [PtMe(nbd)] (nbd = norbornadiene) to give [{PtMe](OH)}]·mHO. Alcohols ROH (R = Me, Et) with cis-[PtMepy] gave [PtMe(OR)(OH)py], which reacted with aqueous HClO solution to give fac-[PtMe(OR)(HO)]ClO in solution. Addition of chloride to this solution caused precipitation of [{PtMe(OR)Cl}]. Reaction of [{PtMeXY}] with AgNO in water gave fac-[PtMeX(HO)](NO) in solution (X = Y = Cl, Br, I or Y = Cl, X = OR); for X = I added acid was necessary to prevent precipitation of [{PtMeI(OH)}]. Reaction of a solution of fac-[PtMeBr(HO)](NO) with AgNO gave fac-[PtMe(NO)(HO)](NO ) in solution, but an analogous reaction with AgSCN gave a complex in solution formulated as fac-[PtMe(SCN)(HO)](NO) only in low yield

Prediction of Ordinal Classes Using Regression Trees

This paper is devoted to the problem of learning to predict ordinal (i.e., ordered discrete) classes using classification and regression trees. We start with S-CART, a tree induction algorithm, and study various ways of transforming it into a learner for ordinal classification tasks. These algorithm variants are compared on a number of benchmark data sets to verify the relative strengths and weaknesses of the strategies and to study the trade-off between optimal categorical classification accuracy (hit rate) and minimum distance-based error. Preliminary results indicate that this is a promising avenue towards algorithms that combine aspects of classification and regression