Direct Oxidation of Europium Metal with Acetic Acid: Anhydrous Europium(III) Acetate, Eu(OAc) 3 , its Sesqui‐hydrate, Eu(OAc) 3 (H 2 O) 1.5 , and the “Hydrogendiacetate”, [Eu(H(OAc) 2 ) 3 ](H 2 O)

Anhydrous europium(III) acetate, Eu(OAc) 3 ( 1 ), its sesquihydrate Eu(OAc) 3 (H 2 O) 1.5 = [Eu 2 (OAc) 6 (H 2 O)](H 2 O) 2 ( 2 ) and the “hydrogendiacetate” [Eu(H(OAc) 2 ) 3 ](H 2 O) = [Eu 2 (OAc) 6 (HOAc) 2 (H 2 O) 2 ](HOAc) 4 ( 3 ) were obtained as colourless single crystals by direct oxidation of europium metal with acetic acid in glass ampoules at 130 °C. The coordination polymer Eu(OAc) 3 ( 1 ) crystallizes in the monoclinic space group C2/c (no. 15) with a = 1126.0(3), b = 2900.5(6), c = 799.1(2) pm, β = 132.03(2)°, V = 1938.6(8) 10 6 ·pm 3 , Z = 4, R 1 = 0.0374 [I>2σ]. The crystals of Eu(OAc) 3 (H 2 O) 1.5 ( 2 ) are monoclinic, space group Cc (no. 9) with a = 1608.7(2), b = 1665.6(2), c = 839.1(1) pm, β = 115.75(9)°, V = 2025.2(4) 10 6 ·pm 3 , Z = 4, R 1 = 0.0424 [I>2σ]. [Eu(H(OAc) 2 ) 3 ](H 2 O) ( 3 ) crystallizes in the monoclinic space group P2 1 /c (no. 14) with lattice parameters of a = 1157.7(1), b = 2131.6(3), c = 901.3(1) pm, β = 110.36(1)°, V = 2085.6(4) 10 6 ·pm 3 , Z = 4, R 1 = 0.0331 [I>2σ]. The linear chain structure of 1 is modified by the addition of one coordinating water molecule in 2 to a corrugated chain whose packing leaves room for crystal water. In 3 the same dimers are observed as in [Eu 2 (OAc) 6 (HOAc) 2 (H 2 O) 2 ] ( 4 ) itself which had previously been synthesized from an ammonium acetate melt. With a higher acetic acid pressure, four molecules of acetic acid per dimer are included in the structure in 3 .