Author:
Corbett M,Hoskins BF,McLeod NJ,O'Day BP
Abstract
The crystal and molecular structures have been determined, by single-crystal X-ray methods, for
each of the isomorphous set of divalent binuclear metal derivatives of 1,3-diphenyltriazene,
abbreviated as dptH, [M(dpt)2]2 where M = Ni, Pd, and Cu. The crystals are composed of discrete
molecular units, of composition M2(dpt)4, which have a syn-syn structure analogous to that of
copper(II) acetate monohydrate with pairs of closely separated metal atoms held together by the
terminal nitrogen atoms of four ligand groups in such a way that the environment of each metal
atom is almost square-planar. The interatomic distances between the pairs of metal atoms, 2.395(3),
2563(1), and 2.441(2) Ǻ for the Ni, Pd, and Cu compounds, are strongly suggestive of metal-metal
bonding. The two N4-planes are almost parallel but the two sets of coordinating nitrogen atoms
are twisted markedly from the eclipsed configuration, the average angle of rotation being about
15°. Crystals of each complex are triclinic with space group P 1. The unit cell parameters in the order
of a, b, c, α, β, and γ are 10.335(3), 15.84(1), 13.546(3)& 100.48(5), 94.47(2), 102.57(3)° for
Ni2(dpt)4; 10.486(1), 15.791(2), 13.751(1)Ǻ, 99.48(1), 93.61(1), 104.37(1)° for Pd2(dpt)4;
10.373(3), 15.916(5), 13.612(3) Ǻ, 99.51(2), 94.85(3), 102.33(2)° for Cu2(dpt)4. The structure of
the nickel complex was solved by the Patterson-Fourier method and the atomic parameters found
for this structure were used as the basis of the structure determinations of the isomorphous copper
and palladium compounds. All three structures were refined by a block-diagonal least-squares
method using 3300 (photographic data) 4065 (counter) and 2753 (counter) independent non-zero
terms for the nickel(II), palladium(II) and copper(II) compounds respectively, converging with
R values 0.13 (isotropic), 0.056 (anisotropic) and 0.069 (isotropic) respectively.