Die Struktur des η1,η2-CS2-verbrückten Komplexes η5-C5H5(CO)3Mo(μ-η1,η2-CS2)Mo(CO)2-η5-C5H5

Unprecedented binding and activation of CS2 in a dinuclear copper(i) complex

“…It turned out that the CS 2 molecule is spanned by both copper centres, to which it coordinates in a double side-on binding mode involving both CQS units (Scheme 1). This is quite remarkable since in all dinuclear CS 2 complexes known so far, where a side-on coordination of CS 2 had been observed, this was restricted to just one CQS unit, while the second sulfur atom was coordinated in an end-on fashion to the second metal ion (Chart 1); [8][9][10][11][12][13] this type of complexation is reminiscent, though, to a singular example of CO 2 coordination, where the latter is bound to a dinuclear Ni 0 -Ni 0 moiety containing a metal-metal bond. 14 In 2 the two copper ions show a distorted trigonal planar coordination geometry (regarding the CQS group as occupying one coordination site) and the Cu-Cu separation amounts to 3.0989( 8 In order to obtain further information concerning the CQS bond strengths a detailed IR spectroscopic study was carried out.…”

“…2). 11,13 After employment of 13 CS 2 in the synthesis of 2 the bands at 1158 cm À1 and 588 cm À1 shifted to 1121 cm À1 and 581 cm À1 , respectively, which suggested their assignment to the CS 2 ligand. The position of the former again reflects an activation of CS 2 compared to the free molecule (u as : 2180 cm À1 ).…”

“…The 13 C NMR spectrum shows a signal at 172.5 ppm, which can be assigned to a CS 2 ligand. Compared to free CS 2 (192.6 ppm) it is thus clearly shifted to higher field, which seemed surprising at first sight: intuitively a lowering of the electron density (and hence a low field shift) is expected upon coordination of CS 2 to a Lewis acidic metal center, and, in fact, the few known CS 2 complexes that were characterized by 13 C NMR spectroscopy displayed signals far above 200 ppm. 7,8 Accordingly, this finding already pointed to an unusual electronic structure.…”

“…A subsequent NBO analysis confirmed that 2 should be viewed as a dinuclear Cu(I) complex (charge at Cu +1.15) with coordinatively bound CS 2 . The charge at the S atoms is almost 0, while the central C atom has a negative charge (À0.9), which explains the unusual chemical shift in the 13 C NMR spectrum and can be rationalized by a donation of electron density from the Cu d orbitals into the CQS p* orbitals, whose coefficients are larger at C. While this orbital interaction dominates the Cu(SCS)Cu bonding, a second contribution comes from the intuitively expected transfer of electron density from the CQS p-bonds into the Cu s orbitals (Fig. S4-S6, ESIw).y Although, both effects lead to a weakening of the CQS bonds, they have clearly retained some double bond character, in agreement with the IR spectroscopic data.…”

Unexpected reactions of (Me2C)(Me2Si)[(η5-C5H3)Mo(CO)3]2 with diazoalkane and carbon disulfide: Activation and cleavage of the NN bond and disproportionation of carbon disulfide

“…by Schwarzhans and coworkers, with one CpMo(CO) 2 group bonded side-on to a C@S bond of CS 2 moiety and the other CpMo(CO) 3 attached end-on to the second sulfur of the bridging CS 2 [12]. The reaction of 1 with CS 2 was carried out in toluene under reflux for comparison.…”