MICROWAVE SPECTRUM AND STRUCTURE FOR CYCLOPENTADIENYL CHROMIUM DICARBONYL NITROSYL

Abstract

The transition metal complex $C_{5}H_{5}Cr(CO)_{2}NO$ is a relatively simple, "piano-stool" type complex which provides the opportunity to compare nitrosyl and carbonyl ligand binding. The nitrosyl and carbonyl ligands form significantly different angles with the $C_{5}H_{5}-Cr$ axis, and this results in a near-symmetric-top inertia tensor for the common isotopomer. For the normal isotopomer, A = 1001.693(2), B = 797.2724(6) and C = 797.0143(6) MHz. The $C_{5}H_{5} - Cr - NO$ angle is $126.9(5)^{\circ}$ and the $C_{5}H_{5}-Cr-CO$ angle is $120.1(2)^{\circ}$. The distance from the Cr atom to the $C_{5}H_{5}$ ring is $z (Cr -C_{5}H_{5}) = 1.88(1) {\AA}$. Other structural parameters are obtained and discussed. The $C_{5}H_{5}$ ring is oriented so that two of the cyclopentadienyl carbon atoms are staggered with respect to the NO nitrogen atom. The $^{14}N$ quadrupole coupling values are $eQq_{aa} = 0.312(2)$ and $eQq_{bb} = -0.448(2)$ MHz.