An ESR investigation of the intermediate obtained from oxidation of sodiumhypophosphite in the process of electroless nickel deposition

The radical intermediate, which is produced in the process of electroless n ickel plating, was detected in the presence of water-soluble trap alpha-4-p yridyl-N-tert-butyl nitrone(POBN) or alpha-phenyl-tert-butyl nitrone(PBN) b y electron spin resonance(ESR) spectroscopy, The results obtained indicated that a 16-line(g=2. 006 1, alpha(C-H)(beta)=1. 98 X 10(-4) T, alpha(P-H)(g amma)=3. 32 X 10(-4) T, alpha(N)=alpha(P)=15. 93 X 10(-4) T) or a 18-line ( g=2. 004 9, alpha(C-H)(beta)=alpha(P-H)(gamma)=2. 38 X 10(-4) T, alpha(P)=1 7. 72 X 10(-4) T, alpha(N)=16. 20 X 10(-4) T) ESR spectrum was observed in the process of electroless nickel plating when spin trap PEN or POBN was ad ded; The spectra-line patterns and hyperfine coupling parameters were great ly indentical with those in the solution composed of Ti3+ (0. 01 mol/L) + H 2O2 (0. 05 mol/L) + H2PO2- (0. 01 mol/L) + POBN or PBN (0. 01 mol/L). There fore, the spin adducts formed in the process of electroless nickel plating could be ascribed to the adducts belonging to HPO2- and POBN or PEN and it follows that the anion radical HPO2- (.) was really produced from the oxida tion of sodium hypophosphite in the process of electroless nickel plating.