The Structure of Nitrosyltricarbonyltriphenylphosphinemanganese, Mn(NO)(CO)₃(P(C₆H₅)₃)

The crystal and molecular structure of nitrosyltricarbonyltriphenylphosphinemanganese, Mn(NO)(CO)₃(P(C₆H₅)₃), has been determined from three-dimensional X-ray diffraction data collected by counter methods. The compound crystallizes in space group C_i ¹-P1 of the triclinic system. There are two molecules in a cell of dimensions a = 9.812 (11), b = 10.803 (12), c = 14.936 (17) Å; α = 117.75 (2), β = 109.12 (3), and γ = 112.73 (2)°. The observed and calculated densities are 1.41 g cm⁻³. Least-squares refinement of the structure has led to a final value of the conventional R factor of 0.056 for the 1297 observed reflections with F² ⩾ 3σ(F²). The structure consists of well-separated monomeric units. Each molecule has the Mn atom at the center of a trigonal bipyramid with the P(C₆H₅)₃ group in an axial position. It has not been possible to distinguish the nitrosyl group from the carbonyl groups from the X-ray data. However, the presence of three carbonyl infrared stretching frequencies implies that the nitrosyl group occupies an equatorial coordination site. It is thus assumed that a carbonyl group is trans to P(C₆H₅)₃ and that the nitrosyl group and two carbonyl groups are disordered among the three equatorial coordination positions. The Mn-P distance is 2.305 (4) Å, the axial Mn-C distance is 1.83 (1) Å, and the equatorial Mn-C (orMn-N) distances are 1.76 (1), 1.78 (1), and 1.80 (1) Å.