Cyanoisocyanoarene Metal Complexes as Building Blocks for Coordination Polymers:  Structural Nonrigidity of a Metal−Nitrile Linkage¹

The complexes trans -[PdI 2 (CNR) 2 ], 1a − 1 e, (CNR = 3-CN−C 6 H 4 −CN ( 1a ), 4-CN−3−C 2 H 5 −C 6 H 3 −CN ( 1b ), c: 4-CN−3−Cl−C 6 H 3 −CN ( 1c ), 4-CN−1,2-(NC) 2 −C 6 H 3 ( 1d ), 4-CN−C 6 H 4 −CH 2 CN ( 1e )), have been prepared. Complex 2a forms a coordination polymer, 3, with copperbis(hexafluoroacetylacetonate) in the ratio of 1:2. The crystal structures of compounds 2b, 2c, 2e, and 3 have been determined by X-ray crystallography. 2b: C 20 H 16 I 2 N 4 Pd, monoclinic space group, P 1 (no. 2), a = 4.630(2) Å, b = 8.365(4) Å, c = 14.835(5) Å, β = 98.03(2)°, Z = 1 1964 unique reflections, R = 0.038, R w = 0.036. 2c: C 16 H 6 Cl 2 I 2 N 4 Pd, monoclinic space group, P 1 (no. 2), a = 7.569(1) Å, b = 8.229(1) Å, c = 9.114(2) Å, β = 77.21(1)°, Z = 1, 1633 unique reflections, R = 0.030, R w = 0.028. 2e: C 18 H 12 I 2 N 4 Pd, monoclinic space group, C 2/ c (no. 15), a = 14.171(3) Å, b = 8.3781(7) Å, c = 18.096(4) Å, β = 103.41(1)°, Z = 4, 2198 unique reflections, R = 0.036, R w = 0.023. 3: C 36 H 12 Cu 2 F 24 I 2 N 4 O 8 Pd, monoclinic space group, P 1 (no. 2), a = 10.946(2) Å, b = 11.315(3) Å, c = 12.261(3) Å, β = 99.39(1)°, Z = 1, 2698 unique reflections, R = 0.049, R w = 0.057.