Pnictogen–thiacrown complexes with Pt(ii) and Pd(ii)

Abstract

Platinum(II) and palladium(II) complexes of the trithiacrown [9]aneS(3) containing a range of Group 15 donors are reviewed. These complexes have the general formula [M([9]aneS(3))(L(2))](n+) where L represents at least one Group 15 donor. Complexes involving pnictogens, with the exception of bismuth, are observed. The complexes generally have an elongated square pyramidal geometry with a long distance interaction to the third sulphur of the [9]aneS(3) which forms the apex of the square pyramid. This axial metal-sulphur distance is quite sensitive to the donor properties of L. Poorer donors such as Sb and As ligands show short axial distances whereas the better N donor ligands show longer distances. Pt(II) complexes of the formula [Pt([9]aneS(3))(EPh(3))(2)](2+) (E = P, As, Sb) show a considerable distortion towards a trigonal bipyramidal geometry due to intramolecular π-π interactions. Over seventy of these types of complexes have been crystallographically characterized and are discussed in this article. Other unique features of the complexes, including NMR spectroscopy, redox chemistry, and electronic spectroscopy, are also discussed.

Synthetic and structural studies of heteroleptic platinum(II) and palladium(II) complexes containing thiacrown and monodentate phosphane ligands

“…Their 13 C NMR spectra are similarly consistent, and further support the structures. Complexation of the metal center by the [9]aneS 3 ligands is confirmed using NMR spectroscopy where the coordinated [9]aneS 3 ligand typically displays its characteristic AA'BB' "butterfly" pattern for the proton NMR spectrum and a single resonance in its 13 C carbon NMR spectrum [1]. Illustrative 1 H and 13 C NMR spectra for the complex [Pt( [9]aneS 3 )(PTA) 2 ](PF 6 ) 2 are presented in Figure 1.…”

“…A water impurity peak is present in the 1 H NMR spectrum, and the [9]aneS 3 region is shown in the insert for both spectra. [1]. In all of the complexes, the 31 P NMR resonance is shifted downfield relative to the free ligands (-100 ppm for PTA, -62 ppm for PMe 3 ) [35].…”

“…Our group and others have previously reported on Pt(II) and Pd(II) complexes with the thiacrown ligand, 1,4,7-trithiacyclononane ( [9]aneS 3 ) and related macrocyclic ligands [1][2][3]. The complexes show an interesting array of unusual properties including the stabilization of rare mononuclear trivalent oxidation states [4][5][6][7][8][9][10], C-H bond activation [12], anion recognition [13], photophysical properties [14,15], antimony-carbon bond activation [16], geometric distortions in five coordination [17], different intermolecular π-π stacking motifs [18], and uncommon metal-metal bond formation [19].…”

“…Heteroleptic Pt(II) and Pd(II) complexes with trithiacrowns form geometries best described as elongated square pyramids, with two of the three sulfur donors lying in the square plane while the third forms a long distance axial interaction. These can vary widely depending upon the donor abilities of the ancillary ligand, surprisingly varying over 0.8 Å [1]. Although a number of different ancillary ligands have now been used to form [9]aneS 3 complexes with both metal ions, monodentate and bidentate phosphanes certainly constitute one of the most important series of ligands studied [20,21].…”

Anion-Dependent Exocyclic Mercury(II) Coordination Polymers of Bis-dithiamacrocycle

“…[1][2][3][4][5][6] In the thiamacrocycles, the electron sufficiency of sulfur donor atoms and the related S···S repulsion in the macrocyclic ring cavity stabilize the trans (or anti) torsion arrangement for the S-C-C-S unit. Such a trans torsion arrangement in the thiamacrocycles have a tendency to lead a metal coordination in an exocyclic (outside the cavity) mode.…”