The preparation and characterisation of rhodium(III) and Iridium(III) half sandwich complexes with napthalene-1,8-dithiolate, acenaphthene-5,6-dithiolate and biphenyl-2,2′-dithiolate

Abstract

The synthesis of rhodium(III) and iridium (III) half sandwich complexes [Cp*M(PEt 3)(S-R-S)], M = Rh, Ir; S-R-S = naphthalene-1,8-dithiolate (NaphthS 2 , a), acenaphthene-5,6-dithiolate (AcenapS 2 , b) and biphenyl-2,2'-dithiolate (BiphenS 2 , c) is reported. We also describe the isolation of a new compound acenaphthene-1,8-dithiol. All complexes have been fully characterised using multinuclear NMR spectroscopy and single crystal X-ray diffraction. The ligands naphthalene-1,8-dithiol (H 2 a), acenaphthene-1,8-dithiol (H 2 b), 1,1'-biphenyl-2,2'dithiol (H 2 c) and benzene-1,2-dithiol (H 2 d) have also been characterised by single crystal Xray diffraction. With the exception of the electron transfer mimics the coordination chemistry of 1,1'biphenyl-2,2'dithiolate has seen little investigation. Two molybdenum based complexes have been synthesised with one bearing an Mo oxygen triple bond.[23, 24] A derivatised version of the ligand has been bound to copper[25] with mono-and dinuclear nickel complexes also reported.[26] There has also been two reports on methods to synthesise titanocene-2,2'-dithiolatobiphenyl.[27, 28] Herein we describe the synthesis of a series of dithiolato complexes bound to rhodium(III) and iridium(III) metal centres. We also report the isolation of a new dithiol, acenaphthene-1,8-dithiol, along with crystallographic studies of naphthalene-1,8-dithiol, 1,1'-biphenyl-2,2'dithiol and benzene-1,2-dithiol. All new complexes and the new dithiol have been fully characterised principally by multinuclear NMR spectroscopy, elemental analysis and single crystal X-ray diffraction. Results and Discussion The diprotic pro-ligands naphthalene-1,8-dithiol [Naphth(SH) 2 ] (H 2 a), acenaphthene-5,6dithiol [Acenap(SH) 2 ] (H 2 b) and 1,1'-biphenyl-2,2'-dithiol [Biphen(SH) 2 ] (H 2 c) were synthesised from their respective disulfides naphtho[1,8-cd]-1,2-dithiole,[32] 5,6dihydroacenaphtho[5,6-cd]-1,2-dithiole[31] and dibenzo[c,e]-1,2-dithiin[33] (Scheme 1). The reduction of disulfides was performed using NaBH 4 ,[34] which was followed by an acidic workup after which all three pro-ligands were isolated as colourless solids, each possessing only a mild thiol odour. Benzene-1,2-dithiol (H 2 d) was prepared according to literature and purified by distillation to afford a colourless liquid with a strong thiol odour (Scheme 1).[35] H 2 a, H 2 c and H 2 d were isolated and spectroscopically characterised earlier,[33, 34, 36] for completeness we report their X-ray structures here. In contrast, H 2 b was not isolated previously, and we report full spectral characterisation as well as its X-ray structure.

Structural diversity of bimetallic rhodium and iridium half sandwich dithiolato complexes

“…The M1-S1 bond lengths [3b 2.343(2) Å; 4b 2.3221(7) Å] and M1-S9 bond lengths [3b 2.373(2) Å; 4b 2.3541 (7) Å] are comparable to other compounds of this type. The peri S···S distance has increased compared to the pro-ligand H 2 b [2.951(2) Å] 37 The metal-sulfur bond lengths in the ionic complexes 3c [2.3708(7)-2.3820(7) Å] and 4c [2.383(1)-2.394(1) Å] and are similar to other complexes bearing bridging dithiolate ligands. The M1-S1, M1-S9 and M1-S1' bond lengths in 3b and 4b are related to M1'-S1', M1'-S9' and M1'-S1 through a crystallographically imposed centre of symmetry.…”

Rhodium(III) and iridium(III) half-sandwich complexes with tertiary arsine and stibine ligands

“…2 A few rhodium complexes with arsine and stibine ligands are known such as the Rh(I) chelate complex [(Ph 2 AsCH 2 AsPh 2 )Rh(CO)Cl] 2 (A), [5] trans-[(Ph 3 Sb) 2 Rh(CO)Cl] (B) [6] and a Rh (III) complex mer-[(Ph 3 Sb) 3 RhCl 3 ] (C) [7] ( Figure 1 [8] . Kemmitt precursors with a series of rather electron poor pnictine ligands (C 6 F 5 ) 3 E, (C 6 F 5 ) 2 PhE and (C 6 F 5 )Ph 2 E (E = P, As, Sb).…”

“…Kemmitt precursors with a series of rather electron poor pnictine ligands (C 6 F 5 ) 3 E, (C 6 F 5 ) 2 PhE and (C 6 F 5 )Ph 2 E (E = P, As, Sb). [9] While all the phosphines formed expected complexes, of arsine ligands only (C 6 F 5 )Ph 2 As and Rh 2 (CO) 4 Cl 2 gave the expected complex [(C 6 F 5 )Ph 2 As] 2 Rh(CO)Cl (F), while no reaction was observed for all other arsine ligands.…”

“…[3] The crystal structures were solved using direct methods and refined by fullmatrix least-squares against F 2 (SHELXL) or heavy-atom Patterson methods and expanded using Fourier M A N U S C R I P T…”

“…[3] In these triethylphosphine complexes the chloride ligands can be displaced by a range of other ligands such as selenide, telluride, azide and acetate, which makes them rather versatile synthons. [3][4] In sharp contrast to phosphines, a search of the Cambridge Structural Database (CSD) for Cp*RhCl 2 and Cp*IrCl 2 fragments coordinated to arsine or stibine ligands resulted in zero hits.…”