Synthesis and Oxidation of a Paddlewheel‐Shaped Rhodium/Antimony Complex Featuring Pyridine‐2‐Thiolate Ligands

Abstract

The paddlewheel-shaped complex [Sb(μ-pyS) Rh] (1) (pyS = 2-S-C H N ) was synthesized from [Rh(pyS)(cod)] (cod=1,5-cyclooctadiene) and Sb(pyS) . Upon oxidation with ONMe , the complex [(μ-O)Sb(μ-pyS) Rh(κ -pyS)] (2) is formed. Both 1 and 2 form dimers and feature short Rh-Sb bonds and bridging pyS ligands. Sb Mössbauer spectro- scopy and computational studies were employed to elucidate the Rh-Sb bonding in 1 and 2. Both covalent (Rh-Sb, X-type Sb ligand) and dative (Rh→Sb, Z-type; Rh←Sb L-type Sb ligand) interactions have to be considered for the description of their bonding situations.

Trivalent Antimony as L-, X-, and Z-Type Ligand: The Full Set of Possible Coordination Modes in Pt–Sb Bonds

“…In order to obtain the δ value of the Sb atom in 3 + , we have chosen complex 3 V (not 3 III ) because the signal of the Sb +V anion was expected not to overlap with the signal of the cation. Moreover, we have included the 121 Sb Mössbauer spectrum of Sb­(pyS) 3 (as a trivalent Sb reference) . Furthermore, as benchmark compounds for TM- and pyS-containing Sb complexes, we include the Mössbauer parameters of the Rh/Sb complex VI and its oxide VII from our previous study in the current discussion (see Table for spectroscopic parameters of all complexes discussed herein).…”

Structural Evidence for Pnictogen-Centered Lewis Acidity in Cationic Platinum-Stibine Complexes Featuring Pendent Amino or Ammonium Groups

“…The chemistry of stibines is attracted a renewed interest because of applications in material science and catalysis [1][2][3][4]. Although a parallel is often drawn with the ubiquitous phosphine ligands, stibines display several atypical traits and can, for example, undergo redox reactions without dissociation of the coordinated metal [5][6][7][8][9][10]. Moreover, while phosphines mostly act as two-electron donor spectator ligands, stibines have been shown to display Lewis acidic properties, even when coordinated to a transition metal [11][12][13][14][15][16][17][18][19][20][21][22].…”

Coordination and Electrochemical Switching on Paddle-Wheel Complexes Containing an As–Ru or a Sb–Ru Axis

“…18 The Ru1−N (1−4) bonds span the narrow range 2.08−2.11 Å for As3, whereas for Sb3, they are 2.11−2.13 Å. The shorter Ru1−N(1−4) bonds may contribute of the more twisted arrangement of trans-located PyO units in As3 [18.30(5) and 19.94 (5)°] in comparison to Sb3 [11.28(4) and 15.90( 4)°], caused by repulsive interactions between the H 6 atoms of the PyO units and the Ru-coordinated NCMe. The Ru1−N5 bond is significantly shorter for As3 in comparison to Sb3 (by about 0.04 Å), thus indicating a stronger electron donation from the trans-disposed ligand in the case of Sb3.…”

“…According to Green’s L/X/Z formalism, this special bonding behavior of the main-group ligand site represents the so-called Z-type σ­(E←TM), and their electronic features have been studied (Chart ). To stabilize cores like Si←TM (TM = Ni, Pd, Pt; I , II ), Sn←TM (TM = Pd, Pt; III ), Sb←Pt ( IV ), Sb←Rh ( V ), Bi←Rh ( VI ), ambidentate monoanionic ligand systems like 2-mercapto-1-methylimidazolyl, 7-azaindolyl, pyridine-2-thiolate, and 6-chloropyridine-2-oxy as well as symmetric monoanionic ligands like formamidinate and trifluoroacetate have been introduced to create paddle-wheel-shaped complex structures where four bridging ligands are incorporated. For all these σ­(E←TM) combinations, the electronegativity of the TM is somewhat larger than that for the main-group metalloid/metal, thus supporting the belonging of the E–TM σ-bond electron pair to the TM, which may then exert its donor ability toward the Lewis acidic site E …”