ABSTRACT
The dirhodium complex, [Rh(2)(C(18)H(15)P)(4)(CO)(2)]·2(CH(3))(2)CO, has crystallographic twofold symmetry and the Rh-Rh distance is 2.6266â (8)â Å. The four atoms proximate to each Rh atom [Rh-P = 2.3222â (7) and 2.3283â (8)â Å, and Rh-C = 1.961â (3) and 2.045â (3)â Å] form a distorted tetra-hedron with large deviations from the putative tetra-hedral angles [r.m.s. deviation = 23â (1)°]. The six angles more closely approximate those of a trigonal bipyramid [r.m.s. deviation = 14â (1)°] with one missing equatorial ligand. The two bridging carbonyl ligands are much more linearly coordinated to one Rh [Rh-C O = 151.0â (2)°] than to the other [127.0â (2)°], and the two Rh(2)CO planes form a dihedral angle of 45.43â (5)°. The two acetone solvent mol-ecules are disordered, and their estimated scattering contribution was subtracted from the observed diffraction data using the SQUEEZE routine in PLATON [Spek (2009 â¶). Acta Cryst.D65, 148-155].
ABSTRACT
Crystal structures of three Ni(CN)(4)(2)(-) salts all with eclipsed ligands and varying axial stacking arrangements are presented. The absorption spectra of all three salts show a slight red shift in the x,y-polarizations and a large red shift in their z-polarizations upon crystallization from solution. Semiempirical ZINDO calculations provide a good model of the solid state, even with only a three-molecule segment, allowing reproduction of the red-shifting and intensity increase upon crystallization found experimentally. The modified nickel beta(s,p) bonding parameter of -5 found appropriate for Ni coordination in our previous studies of single Ni(CN)(4)(2-) planes and a helically stacked Cs(2)[Ni(CN)(4)].H(2)O crystal was changed to -3 for the more parallel-stacked Ni(CN)(4)(2-) planes in this case, while beta(d) was retained at -41. Crystal data are as follows: Na(2)[Ni(CN)(4)].3H(2)O, triclinic space group P1, a = 7.2980(10) A, b = 8.8620(10) A, c = 15.132(2) A, alpha = 89.311(5) degrees, beta = 87.326(5) degrees, gamma = 83.772(6) degrees, V = 971.8(2) A(3), T = 100 K, Z = 4, R = 0.024, R(w) = 0.064; Sr[Ni(CN)(4)].5H(2)O, monoclinic space group C2/m, a = 10.356(2) A, b = 15.272(3) A, c = 7.1331(10) A, beta = 98.548(12) degrees, V = 1115.6(3) A(3), T = 100 K, Z = 4, R = 0.024, R(w) = 0.059; Rb(2)[Ni(CN)(4)].1.05H(2)O, triclinic space group P1, a = 8.6020(10) A, b = 9.6930(10) A, c = 12.006(2) A, alpha = 92.621(6) degrees, beta = 94.263(6) degrees, gamma = 111.795(10) degrees, V = 924.0(2) A(3), T = 100 K, Z = 4, R = 0.034, R(w) = 0.067.
