A number of catena -μ-linkage modes have been observed for the p -xylylenediamine ( p -xda) and Ni(CN) 4 linking octahedral Cd atoms in the X-ray single crystal structures of five inclusion compounds with aromatic guests and a three-dimensional (3D) complex salt: [Cd( p -xda)Ni(CN) 4 ]· o -CH 3 C 6 H 4 NH 2 ( 1 ), [Cd( p -xda) 2 Ni(CN) 4 ]· m -CH 3 C 6 H 4 NH 2 ( 2 ), [Cd( p -xda) 2 Ni(CN) 4 ]·C 6 H 5 OH·H 2 O ( 3a ), [Cd( p -xda) 2 Ni(CN) 4 ]·C 9 H 7 N ( 3b ), [Cd 2 ( p -xda) 3 {Ni(CN) 4 } 2 ]·2C 4 H 5 N ( 4 ), and [Cd(C 6 H 5 NH 2 ) 2 ( p -xda)Ni(CN) 4 ] ( 5 ). Clathrate 1 crystallizes in the triclinic system, space group P 1̄, with a = 6.960(2) Å, b = 7.718(2) Å, c = 9.693(2) Å, α = 90.61(2)°, β = 91.72(2)°, γ = 90.17(2)°, Z = 1, and R = 0.0298 for 2751 reflections; clathrate 2 crystallizes in the triclinic system, P 1̄, with a = 8.149(2) Å, b = 9.577(1) Å, c = 9.865(2) Å, α = 81.03(1)°, β = 94.08(2)°, γ = 106.08(1)°, Z = 1, and R = 0.0490 for 3285 reflections; clathrate 3a crystallizes in the monoclinic system, P 2 1 / m, with a = 8.615(3) Å, b = 17.568(2) Å, c = 9.950(2) Å, β = 105.30(2)°, Z = 2, and R = 0.0519 for 2792 reflections; clathrate 3b crystallizes in the monoclinic system, P 2 1 / m, with a = 8.505(1) Å, b = 17.737(1) Å, c = 10.106(1) Å, β = 102.64(1)°, Z = 2, and R = 0.0422 for 3480 reflections; clathrate 4 crystallize in the monoclinic system, C 2/ c, with a = 19.820(2) Å, b = 7.738(2) Å, c = 31.213(1) Å, β = 109.138(5), Z = 4, and R = 0.0480 for 4092 reflections; complex 5 crystallize in the monoclinic system, C 2/ c, with a = 22.240(1) Å, b = 9.254(1) Å, c = 16.241(1) Å, β = 130.668(3)°, Z = 4, and R = 0.0389 for 2810 reflections. The puckered two-dimensional (2D) network of [CdNi(CN) 4 ] ∞ in 1 is successively spanned by p -xda at every Cd atom to form a 3D host for the o -toluidine. The 2D network in 2 is broken at a couple of CN groups in trans positions of each Ni(CN) 4; instead, the bridge of p -xda is doubled to span the Cd atoms in the host accommodating m -toluidine. The breaking is at cis positions in the hosts of 3a and 3b, enclathrating hydrated phenol and quinoline, respectively. The complicated 3D host structure of pyrrole clathrate 4 is constructed of three single spans of p -xda from one Cd to three other Cd atoms, the respective Cd atoms being interconnected by cis -[−NC−Ni(CN) 2 −CN−] and four-handed Ni(CN) 4 moieties. The bis(aniline)-ligated Cd complex 5 has a 3D structure built from the −[Cd− p -xda−] ∞ and −[( cis -)NC−Ni(CN) 2 −CN−Cd−] ∞ catenations. These structural variations are interpreted in terms of rigidity of p -xda and Ni(CN) 4 skeletons, partial flexibility of the −CH 2 NH 2 substituents in p -xda, flexible utilization of N-ends of Ni(CN) 4 in the catenation, hydrogen bond interactions among the host entities, and host−guest interactions through hydrogen bonds; no strong π−π interactions were observed between the guest and the π-rich host entities.
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Yuge et al. (1996) studied this question.