Synthetic and Structural Study of Cyclopentadienylchromium Dithiocarbamate Complexes and Their Thermolytic Derivatives

Abstract

The reaction of [CpCr(CO)3]2 (1) with the tetraalkylthiuram disulfides [R2NC(S)S]2 (R = Me, Et, i-Pr) has been investigated. At ambient temperature, CpCr(CO)2(η2-S2CNR2) (3) was obtained as air-stable dark red crystals in 81−87% yields from reactions in solution and in quantitative yield from a reaction in the solid state (3a, R = Me); the precursor complex CpCr(CO)3(η1-S2CNMe2) (2a) crystallized out in a 1:1 admixture with 3a from a product solution after 3 days at −29 °C. At 90 °C for 2 h, the same reaction or the thermal degradation of 3 led to the isolation of the thiocarbenoid complex CpCr(CO)2(η2-SCNR2) (4) as dark red crystals (ca. 10%), double cubanes Cp6Cr8S8(η2:η4-SCNR2)2 (5a, R = Me; 5b, R = Et) as dark brown crystals (3−7%), Cp6Cr8S8(η1:η2-S2CNR2)2 (6) as dark crystals (7−14%), Cr(η2-S2CNR2)3 (7) as dark blue crystals (16−21%), Cp2Cr2(CO)4S as dark green crystals (1−3%), and Cp4Cr4S4 (12−22%) as dark green solids. The crystal structures of 2−6 were reported. Unprecedented bridging modes were found in the double cubanes: in 5, two Cr4S4 cubane clusters were linked by a μ-η2:η4-dithiooxamide ligand as well as a Cr−Cr bridge with bond distances of 3.101 and 3.118 Å in the two independent molecules of the compound, and in 6, the cubanes were linked by two μ-η1:η2-dithiocarbamate ligands.

η1and η2complexes of λ3-1,2,4,6-thiatriazinyls with CpCr(CO)x

“…1) in which a CpCr(CO) 3 moiety is coordinated side-on to the ring in an exo orientation, and bonding only through sulfur. The Cr-S distance at 2.4908(11) A ˚is longer than that found in CpCr(CO) 3 {SC(S)N(CH 3 ) 2 }, 7, (2.4406(5)) 11 or CpCr(CO) 3 {SC(NPh)N 3 }, 8, (2.4482(7) A ˚), 12 both of which have unambiguously s-bonded monodentate sulfur coordinated structures.…”

Coordination complexes of thiazyl rings — Synthesis, structure, and density functional theory (DFT) computational analysis of CpCr(CO)x(x= 2, 3) complexes of fluorinated and nonfluorinated 1λ3-1,2,4,6-thiatriazinyls with differing Cr–S bond orders

“…Indeed, in the N,N=-dimethylthiocarbamato-S derivative IX (structure refcode XUJGOY), the metal atom is found to be rigorously in the plane of the ligand and not coordinated perpendicularly to its well-developed system. 49 The 3,5-diphenyl-3 -1-thia-2,4,6-triazinyl radical 2 thus demonstrates once again its remarkable properties in this metal complex. For context, we first recall that 2 is isolated in the solid state as the face-to-face diffusely bonded dimer 2 2 with the property that whilst the strongest linkage is certainly between the two sulfur atoms (d SS = 2.677(3) Å), or 26% < ͚r vdW , steric arguments would expect the geometry to be transoid unless there is also an interaction between the N and C atoms in the adjacent rings.…”

“…The value of a Cr-S single bond length is established in three different ways: First, the sums of the covalent radii as recently redetermined by Cordero et al 71 gives a value of 2.440 Å. Second, the structure types for which a single bond is expected based on chemical intuition, specifically terminal thiolato derivatives of CpCr(CO) 3 (structures with refcodes MAKLOA, RATRIO, and XULGOY), have Cr-S bond distances of 2.4485(8), 44 2.448(3), 47 and 2.4406(8) Å, 49 respectively. Lastly, the full distribution between 2.37 and 2.52 Å for structure types that provide the major Gaussian distribution in the histogram (Fig.…”

“…A precedent for the conversion of such an intermediate has been established in the reaction of 1 with tetraalkyldithiuram disulfides where the low-temperature (-29°C) products are monodentate CpCr(CO) 3 -thiocarbonates, which at ambient temperatures convert quantitatively to bidentate CpCr(CO) 2 -thiocarbonates with the loss of one CO group. 49 Just as in those reactions that produce 3, 6a and 6b are produced as mixtures along with some 4, and the separation is also by fractional crystallization. The structures of the thiatriazinyl complexes 3, 6a, and 6b have been determined by single-crystal X-ray diffraction (Tables 1-4; Figs.…”

Cyclopentadienylchromium Complexes of 1,2,3,5‐Dithiadiazolyls: η2 π Complexes of Cyclic Sulfur–Nitrogen Compounds

“…Our studies on the reactivity of [{CpCr(CO) 3 } 2 ] (2) towards PÀP-and SÀS-bonded substrates-for example, polyatomic main-group elements, [14] or various classes of organic substrates- [15] have shown that the reactions are initiated by the 17-electron radical [CpCr(CO) 3 ]C (2 A), into which 2 readily dissociates in solution. [16] Thus, the resulting primary products from diphenyl dichalcogenide Ph 2 E 2 (E = S, Se, Te), [17] [Ph 2 P(S)S] 2 , [18] the analogous [(iPrO) 2 P(S)S] 2 , [19] tetraalkyldiphosphine disulfide, [20] [R 2 NC(S)S] 2 , [21] [(C 6 H 4 )NSCS] 2 , [22] (C 5 H 4 NS) 2 , [23] and (C 6 H 5 N 4 CS) 2 [24] are inevitably generated in the coupling of 2 A with organic sulfur-or phosphorus-centered radicals. We therefore reasoned that 2 A represents a very mild reagent for radical-coupling reactions with 1, although SÀS bond-cleavage reactions are still expected to dominate.…”