Chemistry and properties of electron-rich bis(phosphine) dicarbonyl molybdenum compounds

Synthesis, Molecular and Electronic Structure, and TDDFT and TDDFT-PCM Study of the Solvatochromic Properties of (Me2Pipdt)Mo(CO)4 Complex (Me2Pipdt = N,N‘-Dimethylpiperazine-2,3-dithione)

“…Molecules of the general formula X 2 Mo(CO) 4 can be synthesized through a ligand-exchange reaction of activated tetracarbonyl precursors (Figure ). Examples of such precursors include (norbornadiene)Mo(CO) 4 , (PPh 3 O) 2 Mo(CO) 4 , (piperidine) 2 Mo(CO) 4 , (CH 3 CN) 2 Mo(CO) 4 , and Mo(CO) 5 X. Weakly coordinated molybdenum complexes are usually isolated prior to the exchange reaction. ,,− Although in acetonitrile Mo(CO) 6 forms a variety of (CH 3 CN) n Mo(CO) 6 - n compounds, it proved unnecessary to isolate these precursor compounds prior to reaction with the Me 2 Pipdt ligand. In the reaction mixture, no (Me 2 Pipdt)Mo(CO) 3 (CH 3 CN) or (Me 2 Pipdt) 2 Mo(CO) 2 compound was detected by ESI-MS, although Mo(CO) 6 forms Mo(CH 3 CN) 3 (CO) 3 and Mo(CH 3 CN) 4 (CO) 2 in acetonitrile.…”

“…The possible active redox behavior of the dithiolate ligand in a variety of transition-metal compounds, including molybdoenzymes, has been discussed in the literature. ,, For example, in complexes of the general formula (R 4 N 2 C 2 S 2 ) Mo(CO) 4 , the molybdenum atom has an oxidation state of 0 and the ligand is viewed as a dithione, while in complexes of the general formula (R 4 N 2 C 2 S 2 )Mo(CO) 2 (PR 3 ) 2 , the same ligand is viewed as a dithiolate and the oxidation state of the molybdenum is 2+. ,, In the latter case, the dithiolate nature of the ligand is suggested because of a short carbon−carbon (1.364 Å) bond in the NC(S)C(S)N fragment and the planar metal-containing chelate ring . In (Me 2 Pipdt)Mo(CO) 4 , the Mo−S distance (2.52 Å) is longer than the typical Mo−S distance of 2.36−2.46 Å observed in numerous dithiolatemolybdenum complexes, which suggests the presence of a Mo−S(thione) coordination and a zerovalent metal. ,,, On the other hand, the observed C−C and C−S distances are ∼0.04 and 0.01 Å shorter, respectively, as compared to the free ligand .…”

“…Electronic Structure and Solvatochromic Effect Calculations. Tentatively, the low-energy band observed in (dithiooxamide)Mo(CO) 4 complexes has been assigned as the metal-to-ligand charge-transfer (MLCT) transition. , To understand the nature of the observed UV−visible transitions and to explain the solvatochromic properties of (Me 2 Pipdt)Mo(CO) 4 , a series of DFT, TDDFT, and TDDFT-PCM calculations have been conducted.…”

“…Herein, we report the synthesis, characterization, and structure of (Me 2 Pipdt)Mo(CO) 4 (where Me 2 Pipdt = N , N ‘-piperazine-2,3-dithione). We chose Me 2 Pipdt ligand because of the conformational flexibility of piperazine ring and its “noninnocent” redox properties in different transition-metal complexes. − The electronic spectra of the (Me 2 Pipdt)Mo(CO) 4 complex exhibit distinct solvatochromic effects, the details of which have been examined using time-dependent density functional theory (TDDFT) approach coupled with polarized continuum model (PCM) algorithm. A combination of experimental and theoretical approaches was used for investigating the influence of geometric and electronic factors on the solvatochromic properties of a molybdenum dithiooxamidetetracarbonyl complex.…”

Metallkomplexe mit 1,2‐Dithion‐Liganden. III. Dithiooxamide als starke Donatoren oder Akzeptoren in Molybdäncarbonylkomplexen

“…D. Komplexe rnit einem sterisch fixierten Tetraalkyldithiooxamid N, N-Diisopropyl-piperazin-2,3-dithion 61 1ii;Bt sich in Pyridin mit P,S1, in schlechten Ausbeuten aus dem cyclischen Oxalsiiureamid erhalten [19,20]. Aus…”