Studies of Ligand Additions to Coordinatively Unsaturated Dirhenium Complexes Containing the Bulky PBu^t₃ Ligand

Abstract

Five new complexes were obtained from the reaction of Re3(CO)12(μ-H)3 with PBut 3. These are Re2(CO)8(μ-PBut 2)(μ-H), 1, Re2(CO)7(μ-PBut 2)(PBut 2H)(μ-H), 2, HRe(CO)4(PBut 3), 3, Re2(CO)6(PBut 3)(μ-PBut 2)(μ-H), 4, and Re2(CO)5(PBut 3)(PBut 2H)(μ-PBut 2O)(μ-H), 5. Compounds 4 and 5 are electronically unsaturated by the amount of two electrons; namely, one of the metal atoms has an 18-electron configuration and the other metal atom has a 16-electron configuration. Compound 4 adds CO and the nitriles MeCN and PhCN, reversibly, to form the electronically saturated 1:1 adducts Re2(CO)7(PBut 3)(μ-PBut 2)(μ-H), 6, Re2(CO)6(NCMe)(PBut 3)(μ-PBut 2)(μ-H), 7, and Re2(CO)6(NCPh)(PBut 3)(μ-PBut 2)(μ-H), 8, respectively. 13CO labeling studies have shown that the CO ligand that is added to 4 to form 6 is added at the electronically saturated metal atom and one of the originally coordinated CO ligands is shifted to the unsaturated metal atom. Compound 5 also adds 1 equiv of CO to form the complex Re2(CO)6(PBut 3)(PBut 2H)(μ-PBut 2O)(μ-H), 9.13CO labeling studies have shown that the added CO ligand was added to the unsaturated metal atom in this case. All of the new compounds were characterized structurally by single-crystal X-ray diffraction analyses.

Re–Re bond breaking of (μ-H)3Re3(CO)11(NCMe) upon reaction with PPh2(o-C6H4)(CH2NMeCH)C60to generates monorhenium and dirhenium phosphino–fullerene complexes

“…The bridging hydride ligand, which occupies a distinct coordination site, has not been located, and is believed to be at the position trans to the Re1-C2 and Re2-C6 bonds, forming a two-electron three-centered bond to the two rhenium atoms. The Re1⋯Re2 distance (3.337 Å) is comparable with (μ-H)Re 2 (CO) 8 (μ-SC 12 H 7 ) (3.345 Å), 12 but is substantially longer than those measured for (μ-H)Re 2 (CO) 8 (μ-PBu t 2 ) (3.1291(2) Å), 13 (μ-H)Re 2 (CO) 8 (μ-SC 6 H 11 ) (3.093(1) Å), 14 and (μ-H)Re 2 (CO) 8 (μ-PFu 2 ) (3.1571(3) Å). 15 For comparison, the Re-Re single bond distance is 3.041(1) Å in Re 2 (CO) 10 .…”

Phosphinoborane-induced fragmentation of the unsaturated hydride H2Re2(CO)8: X-ray structure of HRe(CO)4(κB,P-Ph2PCH2CH2BR2) (where BR2 = 9-borabicyclo[3.3.1]nonanyl) and DFT Evaluation of hydride versus CO coordination by the ancillary borane

“…The hydride resonance recorded for 3 is shifted slightly upfield (ca. 4e5 ppm) compared to the chemical shift reported for the terminal hydride in the rhenium compounds cis-HRe(CO) 4 P (where P ¼ PPh 2 (OMe), PBu t 3 ) and [HRe(CO) 4 ] 2 [m-Cy 2 PO(CH 2 ) 2 OPCy 2 ] [33,34,35]. The 1 H NMR chemical shifts for the 9-borabicyclo[3.3.1]nonanyl moiety, the ethano bridge, and the aryl hydrogens are found in their normal regions, and these data are summarized in the experimental section.…”

Organometallic chemistry of bi- and poly-metallic complexes

“…This unusual ligand addition is thought to be driven by the presence of a bulky P t Bu 3 ligand on the unsaturated metal centre which prevents a ligand approaching this site. 61,62 There has been recent interest in the developement of sensor complexes that can recognise anions. The dinuclear rhenium(I) complex (13) has been synthesised and found to be able to detect and bind dihydrogenphosphate, a process that appears to be driven by an internal hydrogen bonding interaction.…”