Document Type

Honors Project On-Campus Access Only


Advisor: Dr. Paul J. Fischer (Macalester College)


New d6 zerovalent group VI metal (Cr, Mo, and W) tricarbonyls supported by monoanionic tris(diisopropylphosphinomethyl)phenylborate ligands [PhBPiPr3]- ([PhBPiPr3]- = [PhB(CH2PiPr2)3]-) have been synthesized and characterized. Two new ligands featuring 3,5-dimethylphenyl and 3,5-bis(trifluoromethyl)phenyl borate substituents were isolated as thallium salts, and metallated to assess the impact of these 3,5-substituents on the electronic donation of PhBPPh3 ligands towards zerovalent metals. A spectrochemical series of these ligands formulated with IR ν(CO) data and electrochemical half-wave potentials associated with the κ3-phosphine bound M(CO)3 units suggests that tris(phosphinomethyl)phenylborate ligands do not function as “strongly donating scorpionates” towards zerovalent metals. The zerovalent chromium tris(diarylphosphinomethyl)phenylborate tricarbonyl anions were oxidized by ferrocenium to isolate the first structurally characterized paramagnetic d5 zwitterions containing P3Cr(CO)3 units (P = any neutral phosphine). Previously synthesized 17-electron [P3Cr(CO)3]+ species were insufficiently stable under ambient conditions to allow their full characterization.



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