trans-Bis ( tert-butylamine ) dichloropalladium ( II )

Complex (I) exists as two independent square-planar molecules in the asymmetric unit. The orientation of the tertbutylamine groups is such that both molecules are pseudocentrosymmetric. Analysis of the 14 previously reported bis(primary amine)dichloropalladium(II) structures (Fletcher et al., 1996) gives averages of 2.300 (8) Å and 2.047 (9) Å for the Pd—Cl and the Pd—N bonds, respectively, with a mean deviation of the N—Pd—Cl angles of ca 1.4 from the ideal 90 . The Pd—Cl and Pd—N bond lengths in (I) range from 2.3015 (11) to 2.3072 (12) and 2.046 (4) to 2.058 (4) Å, respectively; this indicates that, in this complex, the bulky tertbutyl group has no obvious structural consequence, although the average N—Pd—Cl angle in complex (I) does show a significantly smaller deviation from the 90 required by ideal square-planar geometry [0.46 (molecule 1), 0.37 (molecule 2). The molecules are linked together in a hydrogen-bonding network, resulting in the formation of a two-dimensional layered structure, externally defined by the tert-butyl groups and approximately parallel to (001).

The asymmetric unit of the title complex, trans-[PdCl 2 (NH 2 t Bu) 2 ], consists of two independent square-planar molecules, linked together in a hydrogen-bonding network, with the resultant alignment of the tert-butyl groups defining a two-dimensional layered structure approximately parallel to (001).

Comment
We have noted that the chemistry of tert-butylamine derivatives of palladium frequently differs from other primary amine complexes due to the steric bulk of the tert-butyl group. The availability of crystals of the title complex, (I), allowed comparison with other bis(primary amine)dichloro complexes of palladium to determine the structural consequences of steric bulk.
Complex (I) exists as two independent square-planar molecules in the asymmetric unit. The orientation of the tertbutylamine groups is such that both molecules are pseudocentrosymmetric. Analysis of the 14 previously reported bis(primary amine)dichloropalladium(II) structures (Fletcher et al., 1996) gives averages of 2.300 (8) Å and 2.047 (9) Å for the Pd-Cl and the Pd-N bonds, respectively, with a mean deviation of the N-Pd-Cl angles of ca 1.4 from the ideal 90 . The Pd-Cl and Pd-N bond lengths in (I) range from 2.3015 (11) to 2.3072 (12) and 2.046 (4) to 2.058 (4) Å , respectively; this indicates that, in this complex, the bulky tertbutyl group has no obvious structural consequence, although the average N-Pd-Cl angle in complex (I) does show a significantly smaller deviation from the 90 required by ideal square-planar geometry [0.46 (molecule 1), 0.37 (molecule 2). The molecules are linked together in a hydrogen-bonding network, resulting in the formation of a two-dimensional layered structure, externally defined by the tert-butyl groups and approximately parallel to (001).
Methyl-H atoms were placed in calculated positions and subsequently constrained to an ideal geometry, with C-H distances of 0.97 Å and U iso (H) = 1.5U eq (C), with each group allowed to rotate freely about its C-C bond. The positions of the amine H atoms were identified from a difference Fourier map and allowed to refine freely with fixed isotropic displacement parameters; N-H = 0.79 (6)-0.92 (6) Å . The highest peak is located 1.21 Å from atom Cl21 and the deepest hole 1.47 Å from atom Cl12.

S1. Comment
We have noted that the chemistry of tert-butylamine derivatives of palladium frequently differs due to the steric bulk of the tert-butyl group. The availability of crystals of the title complex, (I), allowed comparison with other bis(primary amine)dichloride complexes of palladium to determine structural consequences of steric bulk.
Complex (I) exists as two independent square-planar molecules in the unit cell. The orientation of the tert-butylamine groups is such that both molecules are pseudo-centrosymmetric. Analysis of the 14 previous bis(primary amine)dichloride palladium structures (Fletcher et al., 1996) gives averages of 2.300 (8) Å and 2.047 (9) Å for the Pd-Cl and the Pd-N bonds, respectively, with a mean deviation of the N-Pd-Cl angles of ca 1.4° from the ideal 90°. The Pd-Cl and Pd-N bond lengths in (I) range from 2.3015 (11) to 2.3072 (12) and 2.046 (4) to 2.058 (4) Å, respectively; this indicates that, in this complex, the bulky tert-butyl group has no obvious structural consequence, although complex (I) does show a significantly smaller deviation from the 90° required by ideal square-planar geometry, [0.455° (molecule 1) 0.375° (molecule 2)]. The molecules are linked together in a hydrogen-bonding network, resulting in the formation of a two-dimensional layered structure, externally defined by the tert-butyl groups and approximately parallel to the c face.

S3. Refinement
The methyl-H atoms were placed in calculated positions and subsequently constrained to an ideal geometry, with C-H distances of 0.97 Å and U iso (H) = 1.5U eq (C), with each group allowed to rotate freely about its C-C bond. The positions of the amine-H atoms were identified from a difference Fourier map and allowed to refine freely with isotropic displacement parameters, N-H = 0.79 (6)  A view of the two independent molecules in (I). Displacement ellipsoids are drawn at the 50% probability level. Tertbutyl H atoms are excluded.

trans-Bis(tert-butylamine)dichloropalladium(II)
Crystal data [Pd(C 4   Rms deviation of fitted atoms = 0.0121 Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.