Silver coordination complexes of 2-(diphenylphosphinomethyl)aminopyridine with weakly interacting counterions

Abstract

A tri-functional ligand (Ph2PCH2)NH(2-C5H4N), DPAP-2, has been synthesized via the Mannich condensation reaction and its coordination behavior has been studied with various Ag(I) salts. The ligand is capable of P-coordination, P,N-chelation, and P,N-bridging to form Ag(I) complexes that range from discrete to 1-dimensional polymeric structures. In the 1:2 reaction of AgBF4 with DPAP-2, a 4-coordinate Ag(I) structure with P,N′-chelation is isolated (1). A counterion effect is observed in the equimolar reactions of AgX (2: X=BF4− and 3: X=tfa−) with DPAP-2, where the structures isolated are a dimer and a 1-dimensional polymer, respectively. When an equivalent of 5,5′-dimethyl-2,2′-dipyridyl (5,5′-dmbpy) was incorporated to the equimolar reaction of AgX and DPAP-2, three isostructural complexes resulted (4: X=BF4−, and supplementary structures S1: X=tfa−, and S2: X=OTf−). In the 2:1:2 reaction of AgX (5: X=BF4− and 6: X=tfa−) with DPAP-2 and 5,5′-dmbpy, two distinct complexes are isolated where DPAP-2 adopts a syn- and anti-arrangement, respectively.