A Comparative Study of Platinum Di (t‐butyl) (¹⁵N₂)diimine and trans‐[(PtCl₂(N‐ligand)PBu₃)] complexes by ¹⁹⁵Pt‐, ³¹P‐ and ¹⁵N‐NMR

Abstract

195Pt‐, 31P‐ and 15N‐NMR. data are presented for [PtCl2 (t‐Bu 15NCHCH15N (t‐Bu)) (η2‐styrene)] (1), trans‐[{PtCl2 (PBu3)}2 (t‐Bu 15NCHCH15N (t‐Bu))] (2), trans‐[PtCl2 (t‐Bu 15NCHCH15N (t‐Bu)) (PBu3)] (3) and various complexes of the type trans‐[PtCl2 (N‐ligand) (PBu3)]. In solution the gross structural features of 1 and 2 are shown to be in agreement with those found in the solid state; namely, 1 contains five‐coordinate Pt and 2 is dinuclear. In 3 Pt is four‐coordinate with only one N‐atom of the diimine ligand being coordinated at −50° in CD2Cl2. The NMR. data for 2 and 3 are compared with those of trans‐[PtCl2 (N‐ligand) (PBu3)] (N‐ligand = pyridine, 2, 6‐dimethylpyridine, (15N)‐hexylamine, (15N)‐t‐butylamine and (15N)‐aniline) and are discussed in terms of the donor and acceptor properties of the N‐ligands.

Tris(phenylimino)-1,3-diphenyl-1,2,3-propantrione: A Model Compound Implicating a Nonhelical Structure for Poly((N-phenylimino)methylene)

“…Assuming a Karplus-like relationship, this isolated imine must be attached at a nearly 90° dihedral angle via a single covalent bond to the remainder of 1 which is composed of an s - trans -conjugated and coupled diimine segment. The assignment of an s - trans diimine moiety is based on the observation of 3 J ( 15 N− 15 N) = 2.7 Hz between the other two nitrogen atoms, consistent with literature precedence …”

Reactions of stable [PtCl2(η2-olefin)(α-di-imine)] complexes. Retention of the five-co-ordinate structure upon halogen exchange and ligand substitution with olefins, α-di-imines, and N,N′-disubstituted 1,2-diaminoethanes

“…In previous papers extensive evidence for the occurrence of reversible o,o-N,N' chelate to o-N unidentate processes in square-planar [PtX2-,( PR& +,(L-L)]X, (n = 0 or 1) complexes has been put forward. [16][17][18][19] In these intramolecular rearrangements the bidentate N-donor ligand changes its point of attachment to the Pt atom (head-to-tail rearrangement) via five-co-ordinate intermediates. The kinetics of this fluxional behaviour depend strongly on the stereochemistry of the N-donor ligands.…”