Crystal Structures of the iso ‐Thiocyanatoberyllates (Ph 4 P) 2 [Be(NCS) 4 ] and (Ph 4 P) 4 [{Be 2 (NCS) 4 (μ‐NCS) 2 }{Be 2 (NCS) 6 (μ‐H 2 N 2 C 2 S 2 )}]

Bis(tetraphenylphosphonium) hexachloridodiberyllate, (Ph 4 P) 2 [Be 2 Cl 6 ], reacts with excess trimethylsilyl‐ iso ‐thiocyanate to give a mixture of colourless single crystals of (Ph 4 P) 2 [Be(NCS) 4 ] ( 1 ) and (Ph 4 P) 4 [{Be 2 (NCS) 4 (μ‐NCS) 2 }{Be 2 (NCS) 6 (μ‐H 2 N 2 C 2 S 2 )}] ( 2 ), which can be separated by selection. Both complexes were characterized by X‐ray diffraction. Compound 1 can be prepared without by‐products by treatment of (Ph 4 P) 2 [BeCl 4 ] with excess Me 3 SiNCS in dichloromethane solution. 1 : Space group I 4 1 / a , Z = 4, lattice dimensions at 100(2) K: a = b = 1091.2(1), c = 3937.1(3) pm, R 1 = 0.0474. The [Be(NCS) 4 ] 2– ion of 1 forms tetragonally distorted tetrahedral anions with Be–N distances of 168.4(2) pm and weak intermolecular S ··· S contacts along [100] and [010]. 2 ·4CH 2 Cl 2 : Space group P $\bar{1}$ , Z = 1, lattice dimensions at 100(2) K: a = 919.5(1), b = 1248.3(1), c = 2707.0(2) pm, α = 101.61(1) °, β = 95.08(1) °, γ = 94.52(1) °, R 1 = 0.103. Compound 2 contains two different anionic complexes in the ratio 1:1. In {Be 2 (NCS) 4 (μ‐NCS) 2 } 2– , the beryllium atoms are connected by (NCS) – bridging groups forming centrosymmetric eight‐membered Be 2 (NCS) 2 rings with distances Be–N of 168(1) pm and Be–S of 235.2(9) pm. The second anion {Be 2 (NCS) 6 (μ‐H 2 N 2 C 2 S 2 )} 2– consists of two {Be(NCS) 3 } – units, which are linked by the nitrogen atoms of the unique dimeric cyclo ‐addition product of HNCS with Be–N distances of 179(1) pm.