STRUCTURES OF NICKEL(II) BISPHOSPHINE AND TRISPHOSPHINE DIISOTHIOCYANATE COMPLEXES

The structures of thanediphosphine-P,P')di(thiocyanato-N)nickel(II), N i(NCS)2(Et2PCH2CH2PPh2) (1), and ylphosphine-P,P',P''}di-(thiocyanato- N)nickel(II), Ni(NCS)2[EtP(CH2CH2PPh2)2] (2), have been determined. Co mplex (1) has square-planar geometry about Ni defined by the bidentate diphosphine ligand and two N-bonded thiocyanato ions. Thiocyanate coo rdination is nearly linear, with Ni-N-C angles of 170.2 (2) and 172.4 (2)-degrees. The P-Ni-P bite angle of the chelating Ph2P(CH2)2PEt2 lig and is 87.05 (3)-degrees. Coordination-sphere bond lengths are Ni-N = 1.876 (3), 1.885 (2) angstrom, Ni-P = 2.1413 (8), 2.145 (1) angstrom. Complex (2) has distorted square-pyramidal geometry about the Ni cente r with the tridentate phosphine ligand and one thiocyanato ligand in t he basal plane. The axial N-bonded thiocyanato ligand deviates from li near coordination, with an Ni-N-C angle of 158.1 (6)-degrees. The P-Ni -P bite angles are 86.20 (9) and 85.53 (9)-degrees. Coordination-spher e bond lengths are Ni-P = 2.223 (2), 2.150 (2), 2.189 (2) angstrom, wh ere the shortest distance is to the central P atom, and Ni-N = 1.896 ( 6) (basal), 2.088 (7) angstrom (axial).