Bonding in PdCl(NO) and Related Nitrosylmetal Species of the Enemark–Feltham {MNO}¹⁰Type

Abstract

The crystal-structure analysis of the coordination polymer PdCl(NO) (1) by Evers et al. shows a two-dimensional PdCl network of four-coordinate Pd atoms and triply bridging chlorido ligands. The fourth ligand at Pd is a terminally bonded nitrosyl ligand in a bent PdNO function (PdÀ NÀ O = 129°). In terms of the Enemark-Feltham notation, 1 is an {MNO} 10 compound which leaves a choice regarding the assignment of the ten electrons as d 10 -Pd 0 Cl À (NO + ), d 9 -Pd I Cl À (NO) or d 8 -Pd II Cl À -(NO À ) with 0, 1 and 2 electrons allocated at the nitrosyl ligand, respectively. The quantum-chemical treatment by DFT methods and subsequent determination of the oxidation states (OSs) by Salvador's Effective-OS (EOS) method shows highly covalent PdÀ NO bonds which narrowly end up on the Pd 0 Cl À (NO + ) side in the course of the OS assignment's heterolytic bond-cleavage procedure. Related halonitrosyls are included to examine the obvious suitability of both linear and bent MNO units as 'ground-state canditates' of {MNO} 10 systems. Local-mode analysis confirmed the recently formulated weakening of both the metalÀ nitrosyl and the NÀ O bond on bending a linear MNO function.

The dn Number in Transition Metal Chemistry: Its Utility and Limitations

“…For further recent examples of papers by Klüfers et al that deal with the bonding in metal nitrosyls, see refs. [63,64] and for an interesting discussion about how to consider the NO ligand in the complex [Tp Me 2 ]NiNO (where [Tp Me 2 ] is the tris(3,5dimethylpyrazolyl)hydroborato ligand), see refs. [65,66].…”

“…As a result, Enemark and Feltham proposed the {MNO} n notation (cited earlier) where the value of n is the d n number of the complex when the NO ligands are treated as NO + [48,49] (Appendix A Note 16). Nevertheless, the NO + /NO − classification remains a topic of continued interest, as demonstrated in the recent publications by Klüfers et al concerning whether or not a range of {CoNO} 8 complexes should be classified as Co(III)-NO − or Co(I)-NO + [61,62] (Appendix A Note 21) [63][64][65][66][67][68].…”

T-Shaped Palladium and Platinum {MNO}10 Nitrosyl Complexes

“…Structures were optimized at the M06/def2SVP level of theory and provide geometric parameters in very good agreement with experiment . Analysis using Salvador’s Effective Oxidation State (EOS) method indicates that, while the M–NO bonds have a high degree of covalency, the electron pair goes to the metal when assigning formal oxidation states in these complexes (M 0 /NO + ). , Subsequent energy decomposition analysis was carried out using the extended transition state (ETS) method in combination with natural orbitals for chemical valence (NOCV) theory at the ZORA-M06/TZ2P level of theory. , The calculated bond dissociation energies ( D e /kcal·mol –1 ) increase in the order 1 (108.2) < 3 (113.5) < 2 (117.3) < 4 (122.5), viz. M = Pd < Pt and R = t Bu < Ad.…”