Nitrosyl complexes linear

Figure 11.13 Structures of polynuclear nitrosyl complexes (a) ((Cr( j -C5H5)(NO))2(M2-NH2)(M2-NO) showing linear-terminal and doubly bridging NO and (b) (Mn3( j -C5H5)3( 3-NO)3( 3-NO)] showing double-and triply-bridging NO the molecule has virtual symmetry and the average Mn-Mn distance is 250 pm (range 247-257 pm).

Ruthenium probably forms more nitrosyl complexes [115] than any other metal. Many are octahedral Ru(NO)Xs systems, where X5 can represent a combination of neutral and anionic ligands these contain a linear (or very nearly) Ru-NO grouping and are regarded as complexes of ruthenium(II). They are often referred to as (Ru(NO) 6 systems. 

Method (i) is a route commonly utilized in monometal nitrosyl complexes. The nitrosyl ligand may function as (formally) a three-electrop donor (NO+) with a linear bonding mode, or as (formally) a one-electron donor (NO ) with a bent (—120°) M-N-0 arrangement. Conversion of the M-NO system to a M-NO system has two effects. First, it increases the metal oxidation state by two second, it generates a vacant coordination site. The dinitrosyl cluster Os3(CO)8(NO)2, which has... 

Nitrosyl complexes are of two types, depending on the orientation of the NO group with respect to the metal atom. In a linear complx, the M—N—O bond angle is... 

In a recent review (215), a qualitative MO scheme is presented for the iron nitrosyl complexes. The two major features in this scheme are that (1) the Fe- NO group is linear because the 3b and 3fe2 orbitals are not occupied and (2) the highest occupied (and slightly antibonding) orbital is 5a,. 

The geometry of the starting complex is established from an x-ray study to be octahedral with a bent NO- ligand. The related 5-coordinate complex [Co(NO)(diars)2]2+ in which the nitrosyl is linearly coordinated does not protonate. 

Table 1 IR and Structural Data on Linear Mononuclear Nitrosyl Complexes...

It should be emphasized that the NO+ and NO- character of NO and the linear or bent angle in a nitrosyl complex do not necessarily imply that NO would be released from the complex in the free form NO or as NO+ or NO-. 

An interesting synthesis of the cyclopentadienyl bisphosphine ruthenium nitrosyl complex 9 involves the thermal displacement of both phenyl groups from (i75-C5H5)Ru(NC))PIi2 (8) with a chelating diphosphine [Eq. (6)] (72). Infrared data indicate that the nitrosyl ligand is linear (3 e ... 

---