Partial metathesis reactions of ytterbium trichloride hexahydrate (YbCl 3 ·6H 2 O) with silver (I) dicyanamide (AgN (CN) 2) in water yielded colorless single crystals of the pentahydrated mixed‐anionic salt YbN (CN) 2 2 Cl·5H 2 O from the clear brine after the removal of the white AgCl precipitation. The title compound crystallizes in the triclinic space group P with the lattice parameters a = 926. 57 (5) pm, b = 1111. 65 (6) pm, c = 1252. 08 (7) pm, α = 97. 239 (2) °, β = 94. 641 (2) °, γ = 103. 038 (2) ° for Z = 4. Its crystal structure consists of two crystallographically independent eightfold coordinated Yb 3+ cations displaying four terminal nitrogen atoms (d (Yb–N) = 237–241 pm) from four dicyanamide anions and four oxygen atoms (d (Yb–O) = 230–238 pm) from water molecules. Surprisingly, both cations have no contact to the Cl – anions according to YbN (CN) 2 2 (H 2 O) 4 Cl·H 2 O. The N (CN) 2 – anions exhibit their typical boomerang shape N≡C–N–C≡N – with bond lengths and angles (d (C≡N) = 114–116 pm, d (C–N) = 130–132 pm, ∡ (C–N–C) = 118°–119°, ∡ (N–C≡N) = 174°–175°) in familiar ranges. They are part of SiS 2 ‐related chains (H 2 O) 4 (Yb1) [N (CN) 2 8/2 (Yb2) (H 2 O) 4 ] 2+, which even suggest the more simple motif (H 2 O) 2 Yb[N (CN) 2 4/2 (H 2 O) 2 ] + in a smaller unit cell. But the two crystallographically diverse Cl – anions make the difference: one of them, (Cl2) –, resides far away from its inversion‐symmetric counterpart, whereas the other one is connected via hydrogen bridges of two water molecules to its point‐inverted one, forming a dimer (Cl1) (H–O–H) 2 (Cl1) 2– with an inversion center and (Cl1) – ··· (Cl1) – distances of 481 pm. Nevertheless, both chloride anions are surrounded by five H 2 O molecules each.
Locke et al. (Mon,) studied this question.