Synthesis and crystal structure of KBi(C6H4O7) · 3.5H2O

Abstract

A novel compound, KBi(C6H4O7) · 3.5H2O (I), has been synthesized in the Bi(NO3)2-K3(HCit) system (HCit3− is an anion of citric acid C6H8O7) at a component ratio (n) of 8 in a water-glycerol mixture, and its crystal structure has been determined. The crystals are unstable in air. The crystals are triclinic: a = 7.462 A, b = 10.064 A, c = 17.582 A, α = 100.27°, β = 99.31°, γ = 105.48°, V = 1221.2 A3, Z = 2, space group % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqipu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuaiqaig% dagaqeaaaa!3775! $$P\bar 1$$ . In the structure of I, asymmetric binuclear fragments [Bi2(Cit4−)2(H2O)2]2− are linked through inversion centers into polymeric chain anions. Ions K+ and crystal water molecules are arranged in channels between the chains. The Bi(1)...Bi(2) distances in the binuclear fragment are 4.62 A, and the Bi(1)...Bi(1) and Bi(2)...Bi(2) distances between bismuth atoms in the chain are 5.83 and 5.95 A, respectively. The chains are linked through bridging oxygen atoms of the ligands Cit to form layers. In the centrosymmetric four-membered chelate ring Bi2O2 formed through Bi-O(Cit) bonds, the distances Bi(1)-Bi(1) are equal to 4.55 A, and Bi(1)-O are 2.66 and 2.84 A. The Bi-O bond lengths in I are in the range 2.12–3.16 A. The Cit ligands act as hexadentate chelating/bridging ligands.