Reactivity of the di-mu-hydroxo-complexes [{Pd(N-N)}(2)(mu-OH)(2)][ClO4](2) (N-N = bis(pyrazol-1-yl)alkanes) towards protic electrophiles. Hydration of coordinated nitriles at a palladium(II) site

The hydroxo-complexes [{Pd(mu-OH)(N-N)}(2)][ClO4](2) (N-N = bpzm:bis(pyrazo l-1-yl) methane: a-compounds, bpzm*:bis(3,5-dimethylpyrazol-1-yl)methane; b -compounds) react with a wide variety of weak protic electrophiles H(LL) in a 1:2 molar ratio to give the mononuclear cationic palladium(II) derivativ es of general formula [Pd(LL)(N-N)][ClO4] [LL = 2-pyridine-methoxo (OCH2-py ) (1a,b); picolinate (pic) (2a,b); 8-hydroxiquinolinate (oxin) (3a,b)] or t he dinuclear complexes [{Pd(N-N)}(2)(mu-ox)][ClO4](2) [ox = oxalate: (4a,b) ] and [{Pd(mu-LL)(N-N)}(2)[ClO4](2) [LL = pyrazolate (pz) (5a,b); p-thiocre solate (SC,H,Me-p) (6a,b); triazolate (tz) (7b); thiophenolate (SPh) (8b)] when reacting with oxalic acid, azoles or thiols in the same molar ratio. I n a related reaction, deprotonation of secondary amines by the hydroxo-comp lexes in the presence of carbon disulfide leads to the corresponding dithio carbamate complexes [Pd(S2CNR2)(N-N)][ClO4] [R = Me (9a,b), Et (10a,b) C5H1 0 (11a,b)]. The hydroxo complexes also promote the nucleophilic addition of water to pyridine-2-carbonitrile and mononuclear complexes containing pyri dine-2-carboxamidate ligands are formed (12a,b). The new compounds have bee n characterized by partial elemental analyses, conductance measurements and spectroscopic (IR, H-1 and C-13 NMR) methods. The crystal structures of co mpounds 6b and 11a have been determined by X-ray diffraction analysis. (C) 2000 Elsevier Science Ltd. All rights reserved.