Silver(I) and gold(I) complexes of hydrotris(3,5-dimethylpyrazol-1-yl)borate: synthesis, spectroscopic and structural characterization, and reactivity toward C-, N- and S-donor ligands.

Abstract Reaction of Ag(NO 3 ) with 1 equiv of K[HB(3,5-Me 2 pz) 3 ] (pzH=pyrazole) and 1 equiv of PR 3 (R OPh or C 6 F 5 ) in methanol provides two new air stable derivatives {[HB(3,5-Me 2 pz) 3 ]Ag(PR 3 )}. When the interaction between Ag(O 3 SCF 3 ), CNR (R Bu t or cyclohexyl), and K[HB(3,5-Me 2 pz) 3 ] was carried out in CH 2 Cl 2 at 0°C the air stable neutral compounds {[HB(3,5-Me 2 pz) 3 ]Ag(CNR)} were obtained. The borderline monodentate imidazole (ImH) reacts with the dinuclear {[HB(3,5-Me 2 pz) 3 ]Ag} 2 yielding the mixed-ligand complex {[HB(3,5-Me 2 pz) 3 ]Ag(ImH)}. On the other hand when the soft donor 1-methyl-2-mercaptoimidazole (Hmimt) was employed, no stable compound was obtained. We also synthesized [Phen 2 Ag](O 3 SCF 3 ) (Phen=1,10-phenanthroline) and its reaction with K[HB(3,5-Me 2 pz) 3 ] yielded the complex {Phen[HB(3,5-Me 2 pz) 3 ]Ag}, which is not fluxional in solution. Instead only unmanageable material was obtained from the reaction between (Hmimt) 2 Ag(O 3 SCF 3 ) and K[HB(3,5-Me 2 pz) 3 ]. Finally, the gold(I) complex [HB(3,5-Me 2 pz) 3 ]Au(PPh 3 ) 2 was obtained when the reaction between PPh 3 AuCl and [HB(3,5-Me 2 pz) 3 ] was carried out in presence of 1 equiv of PPh 3 . The solid state structures of {[HB(3,5-Me 2 pz) 3 ]Ag(PPh 2 Me)} and {[HB(3,5-Me 2 pz) 3 ]Ag(P- o -tolyl 3 )}, show that the silver(I) atoms are in a strongly distorted tetrahedral environment, with the [HB(3,5-Me 2 pz) 3 ] − donor acting in the tridentate form. The Ag–P and Ag–N bond distances in {[HB(3,5-Me 2 pz) 3 ]Ag(PPh 2 Me)} are 2.336(2) A and 2.316(6), 2.336(5) and 2.329(6) A, respectively; they are shorter than in the more sterically hindered {[HB(3,5-Me 2 pz) 3 ]Ag(P- o- tolyl 3 )} (Ag–P: 2.375(2) A; Ag–N: 2.361(4) A). The ligand bite N–Ag–N ranges from 82.1(2)° to 84.8(2)°, whereas the N–Ag–P angle ranges from 125.1(1) to 134.1(1)°.