SCHEDULED MAINTENANCE
Oxidation and reduction of cis-bis(2,2′-bipyridine)dicarbonylmolybdenum(0) and -tungsten(0). Preparation of bis(2,2′-bipyridine)-dicarbonyl(solvent)molybdenum(II) bis(tetrafluoroborate) salts and their reaction with isocyanides
Abstract
Oxidation of cis-[M(CO)2(bipy)2](M = Mo or W; bipy = 2,2′-bipyridine) with silver(I) tetrafluoroborate in solution produces red-brown, diamagnetic [Mo2(CO)4(bipy)4][BF4]2 or orange cis-[W(CO)2(bipy)2][BF4]. [Mo2(CO)4(bipy)4][BF4]2 dissociates in acetone solution to form green, paramagnetic trans-[Mo(CO)2(bipy)2][BF4]. Addition of one equivalent of silver(I) ion to the metal(I) cations in solution produces cis-[Mo(CO)2(bipy)2(solvent)][BF4]2(solvent = MeCN, Me2CO, or H2O) or cis-[W(CO)2(bipy)2][BF4]2. Oxidation of cis-[Mo(CO)2(phen)2](phen = 1,10-phenanthroline) with Ag[BF4](two equivalents) in acetonitrile produces cis-[Mo(CO)2(phen)2(NCMe)][BF4]2. cis-[Mo(CO)2(bipy)2] reacts with [NO][PF6] to form [Mo(CO)(NO)(bipy)2][PF6]. Addition of isocyanides, RNC (R = Et or C6H4Me-p), to cis-[Mo(CO)2(bipy)2(NCMe)][BF4]2 in acetonitrile solution at room temperature produces, successively, [Mo(CNR)3(bipy)2][BF4]2 and [Mo(CNR)5(bipy)][BF4]2. The new complexes have been characterised by microanalysis, spectroscopy [i.r., 1H, and 13C n.m.r., mass (fast atom bombardment), electronic absorption], conductivity measurements, and electrochemistry in solution. Reduction of cis-[Mo(CO)2(bipy)2] with sodium amalgam in tetrahydrofuran solution produces paramagnetic cis-[Mo(CO)2(bipy)2]˙–. Reaction of CNEt with [{Mo(CO)4Cl2}2] in dichloromethane, followed by anion exchange with [NH4][PF6] produces [Mo(CNEt)7][PF6]2.
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