Bis(η²-cyclooctene)(N,N-dimethyldithiocarbamato-S,S′)iridium(I), the first example of a tetracoordinate Ir^Icomplex containing two π-bonded monoolefin ligands

Abstract

The title compound consists of [Ir(C3H6NS2)(C8H14)2] molecules lying on positions with site symmetry 2. Both the coordination plane, defined by the metal, S atoms and the two midpoints of the olefinic bonds, and the dithiocarbamate chelate system are essentially planar. The orientation of the coordinated C=C bonds with respect to the coordination plane is close to perpendicular [(C=C,Ir)/(Ir,S,S) interplanar angle: 79.4 (2) degrees ]. The Ir-C distances are 2.144 (3) and 2.155 (3) A, and the Ir-S bond length is 2.3661 (8) A. Due to pi-coordination, the olefinic bonds are elongated to 1.424 (5) A. The cyclooctene ligands adopt a crown conformation.

Pyridine-based SNS-iridium and -rhodium sulfide complexes, including d8–d8 metal–metal interactions in the solid state

“…In bis(g 2 -cyclooctene)(N,N-dimethyldithiocarbamato-S,S')Ir(I), the Ir-C bonds are 2.144(3) and 2.155(4) A ˚, respectively. 21 The C17-C16 bond length (1.392(9) A ˚), which is longer then the double bond of non-complexed cyclooctenes (1.34 A ˚), 22 indicates significant back bonding to the alkene, although it is lower than in the cases of the phosphine-based complexes [( iPr PNP)Ir(COE)][PF 6 ] and [(PNN)Ir(COE)][PF 6 ] (1.409(10) 20 and 1.407(10) 20 A ˚, respectively). The analogous rhodium complex 2 gives rise in the 1 H NMR to a sharp singlet in the region of the benzylic protons at room temperature and only upon cooling to 213 K does it split into an AB system, similar to the one observed in the spectrum of 1 at 233 K. 1 H NMR analysis of this dynamic behavior 17 over the range of 190-330 K yields the free energy of activation value DG # 240 = 47.79 ± 0.8 kJ mol −1 (T c = 240 K for 2).…”

103Rh NMR Chemical Shifts in Organometallic Complexes: A Combined Experimental and Density Functional Study

“…1' 2' RhÀC CO RhÀQ D C CO ÀRhÀQ Rh ÀC CO ÀO R h ÀCO CÀRhÀC 1.808(2) [b] 1.936(2) [b] 0.018 135. [f] MÀRhÀM' [f] RhÀO R h ÀC1 RhÀC2 OÀRhÀO C 1 ÀRhÀC2 2.143 [g] 84.5 [g] 2.051 (4) [28] [c] In this case from model DFT fully optimised structure; [d] From the X-ray structure of [Rh 4 (CO) 12 ] (FOWTIU); [29] [e] From the X-ray structure (BOZWOC); [30] [f] M denotes the middle point of cod olefinic bonds; MÀRhÀM' indicates the angle formed by rhodium and the two middle points of the olefine bonds in a cod group; [g] From the X-ray structure (HUFQEE); [31] [h] From the X-ray structure; [15b] [i] From the X-ray structure of trans-[Rh(CO) 2 I 4 ] À ; [32] [l] From the X-ray structure (CLMSRH); [33] [m] From the X-ray structure (ACACRH10). [34] larger TZ2P level (see Table 5).…”