Molecular systematics in metal tetrathiolenes. A novel 2-, 4-, 6-, 8-, and 12-electron-donating ligand system upon coordination to one, two, two, three, and four metals, respectively

Article abstract of DOI:10.1021/ic50226a041

New synthetic and structural evidence has led to a unified pattern of the versatile coordination chemistry of the tetrathiolene ligands: tetrathionaphthalene (TTN, C₁₀H₄S₄), tetrachlorotetrathionaphthalene (TCTTN, C₁₀Cl₄S₄), and tetrathiotetracene (TTT, C₁₈H₈S₄). These ligands can act as, formally, 2-, 4-, 6-, 8-, and 12-electron (ne) donors (assumed to be neutral) when coordinated to one, two, two, three, and four metals, respectively. Molecular designs via electronic, steric, and reactivity controls give rise to an unusual array of novel metal tetrathiolene complexes or clusters. This paper reports the preparations, characterization, and chemical and physical properties of the following novel systems: (a) 2e systems, (Ph₃P)₂(CO)-XIr(TCTTN) where X = Cl, H; (b) 4e systems, (Ph₃P)₄Pt₂(TTN) (reported elsewhere); (c) 6e systems, (Ph₃P)₂-(CO)₂I₂Ir ₂(TCTTN); (d) 8e systems, (Ph₃P)₂Pt(TCTTN)Ir₂I₂(CO) ₂(PPh₃)₂; (e) 12e systems, (Ph₃P)₂(CO)₂H₂Ir ₂-(TCTTN)Ir₂I₂(CO)₂(PPh ₃)₂. Single-crystal X-ray structural determinations revealed that the 2e systems (Ph₃P)₂(CO)-XIr(TCTTN) have an octahedrally coordinated iridium with two triphenylphosphines in a trans configuration and an equatorial plane containing two sulfur atoms from TCTTN, the carbonyl group, and the X atom; the molecule as a whole, however, deviates significantly from planarity. High-pressure liquid chromatography using gel permeation was used to help separate and identify the products.