Stretching frequencies, nitrosyl groups

Another related feature is the observation that monomeric organo-lanthanides (Lewis acids) interact with nitrosyl groups. This occurs for example with CrCl(n-Cp)(NO)2 and (MeCp)3Sm. Adduct formation through the oxygen atom is proposed in order to explain the decreases that are found in the NO stretching frequencies.105... 

The oxidation numbers of the metals in the nitrosyl compounds depend on whether this ligand is considered NO , NO, or NO . However, it is generally assumed that, at least in the diamagnetic nitrosyl compounds which show N—0 stretching frequencies above 1700 cm.""S the nitrosyl group is to be considered as NO+ (75). Therefore, the nitrosyl compounds reported below are to be considered as nickel(O), palladium(O), and platinum (0) derivatives. 

The product isolated from the reaction of [RhCl(S02)(PR3)2] R = Cy, n-butyl ("Bu), tso-propyl ( Pr) with gaseous nitric oxide has proved difficult to characterize uniquely (68). Analytical data suggested the formulation [RhCl(NO)2(PR3)2] and the IR spectrum gave two stretching frequencies at 1638 and 1664 cm consistent with structure (10), which contains two bent nitrosyl groups. The crystal structures of both the tri-n-butylphosphine and tricyclohexylphosphine derivatives con-... 

The stretching frequency of the nitrosyl group is sensitive to other bonding parameters and is Ibiind over a range of about 1(XX)-7IMX) em. For carbonyl-nitro.syl complexes, the N—O stretch is typically found between 1500 and l9(X)cm. ... 

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