105015-71-2

Upstream product

• 931-53-3 Cyclohexyl isocyanide 
• 23526-71-8 cis-[Mo(CO)2(NCMe)2(PPh₃)2] 
• 23526-71-8 cis,trans-Mo(CO)2(PPh₃)2(NCMe)2 

Relevant academic research and scientific papers

Reversible intramolecular isomerization associated with the electron-transfer reactions of mixed-carbonyl-isocyanide-phosphine complexes of molybdenum of the type [Mo(CO)2(CNR)2(PR′3)2] +/0

Neutral species of the type Mo(CO)2(CNR)2(PR′3)2 (R = methyl, isopropyl, tert-butyl, cyclohexyl, p-tolyl, xylyl, mesityl, 2,4,6-tri-tert-butylphenyl; PR′3 = PEt3, P-n-Pr3, PEt2Ph, PMePh2, PPh3) have been synthesized and found to exist as a single isomer with a trans disposition of phosphine ligands and cis arrangements of the pairs of CO and RNC groups in the case of R = alkyl and PR′3 = any phosphine except (in some instances) PPh3. For the analogous aryl isocyanide complexes, spectroscopic evidence (IR and 1H and 31P{1H} NMR) suggests that a mixture of isomers is present. In all instances (i.e., R = alkyl and aryl) electrochemical and chemical oxidations afford the paramagnetic 17-electron all-trans cations [Mo(CO)2(CNR)2(PR′3)2] +, which have been isolated as their PF6- salts in a few cases. The monocations have been characterized by IR and X-band ESR spectroscopies. Rereduction of these cations results in a very rapid reisomerization to the isomer or equilibrium mixture of isomers that are present in the parent neutral complexes, except in the cases of Mo(CO)2(CNXylyl)2(PEt2Ph)2, Mo(CO)2(CN(t-Bu3Ph))2(PMePh2) 2, and Mo(CO)2(CN(t-Bu3Ph))2(P-n-Pr3) 2. For these three complexes rereduction affords solutions of the neutral all-trans isomers, which can be characterized spectroscopically before they slowly reisomerize to the mixtures of isomers that contain cis CO groups. From cyclic voltammetric measurements on solutions of these complexes in 0.1 M n-Bu4NPF6/CH2Cl2, the equilibrium constants for the redox cross-reactions trans0 + cis+ ? trans+ + cis0 show that these equilibria lie far to the right; this is attributable to the high thermodynamic stability of the trans+ and cis0 species. The homogeneous chemical rate constants for the cis-trans isomerizations of Mo(CO)2(CNR)2(PR′3)2 have been evaluated. For the processes (Chemical Equation Presented) it is clear that k1 > k2. The intramolecular isomerizations can be interpreted in terms of sequential trigonal twists.

Srereochemical and Electronic Control of M-SO2 Bonding Geometry in d6 Molybdenum and Tungsten SO2 Complexes: Novel η1 η2 SO2 Linkage Isomerization in Mo(CO)2(PPh3)2(CNR)(SO2) and Structures of Mo(CO)3(P-i-Pr3)2(SO2) and 2

New complexes, mer,trans-M(CO)3(PR3)2(SO2) (M = Mo, W; R = Ph, Cy, i-Pr) (I), cis,trans-Mo(CO)2(PPh3)2(SO2)(L) (L = NCMe, py, CNCy, CN-t-Bu and CN(p-tolyl)) (II), and 2, have been prepared and characterized by infrared spectroscopy, 17O and 31P NMR spectroscopy, and X-ray crystallography.Syntheses for fac-Mo(CO)3(η2-SO2)(LL) (LL = dppe, bpy, phen, 2 py) have also been developed.Depending upon L, II has been found to coordinate SO2 either in the S-bonded (η1 planar) or O,S-bonded (η2) geometries.Remarkably, for L = CNCy or CN-t-Bu, II has been found to contain, in the solid state, an apparent equimixture of both coordination types.Isomerization of fac-M(CO)3(dppe)(η2-SO2) (M = Mo, W; dppe = 1,2-bis(diphenylphosphino)ethane) to an η1-planar SO2 form, mer-M(CO)3(dppe)(SO2), has also been found to occur.Thus, control of the SO2 coordination geometry has been achieved by varying either the electronic properties of the ancillary ligands or their disposition with respect to the SO2.The X-ray crystal structure of mer, trans-Mo(CO)3(P-i-Pr3)3(SO2) revealed η1-planar SO2 binding, the first example of this geometry for group 6 metals.The M-S distance, 2.239 (3) Angstroem, is the longest such distance for this geometry recorded to date.Crystal data: Pbca, Z = 8, a = 24.712 (8) Angstroem, b = 16.033 (6) Angstroem, c = 14.058 (5) Angstroem, R = 0.079 for 2934 reflections with I 2?(I).The structure of 2 showed a novel SO2 bridging geometry in which all three atoms of SO2 are metal coordinated.Crystal data: P, Z = 1, a = 14.833 (4) Angstroem, b = 9,264 (2) Angstroem, c = 10.808 (2) Angstroem, R = 0.039 for 3282 reflections with I 2?(I).