Synthesis of and Small Molecule Coordination to Highly Electrophilic Cationic Manganese(I) and Rhenium(I) Carbonyl Complexes with Tied-Back Phosphites

Formally 16e highly electrophilic fragments [Mn(CO) 4 (L)][BAr F ] with a tied-back phosphite (L = P(OCH 2 ) 3 CMe) coordinate Et 2 O ( 5b ) or cis -cyclooctene ( 5c ) and are prepared by reaction of the neutral methyl complex Mn(Me)(CO) 4 (L) with [H(OEt 2 ) 2 ][BAr F ] or [Ph 3 C][BAr F ] in the presence of cis -cyclooctene (cco), respectively. The solvent-bound rhenium complexes [Re(CO) 4 (L)(CH 2 Cl 2 )][BAr F ] ( 6a ) and [Re(CO) 3 (L) 2 (CH 2 Cl 2 )][BAr F ] ( 7a ) are prepared similarly by reaction of the respective neutral precursors with [Ph 3 C][BAr F ] in CH 2 Cl 2 . The CH 2 Cl 2 molecule binds tightly to the Re(I) center and could not be removed under high vacuum for hours. However, the CH 2 Cl 2 is readily displaced by Et 2 O, cco, and Et 3 SiH to afford ether-, olefin-, and silane-coordinated complexes 6b − d and 7b − d, respectively. While the η 2 -(H−SiEt 3 )-coordinated 7d is stable in solution at room temperature and is a rare example of an isolable cationic silane complex, the more electrophilic analogue 6d readily decomposes at room temperature to give the hydride-bridged complex {[ cis -Re(L)(CO) 4 ] 2 (μ-H)}{BAr F } ( 10 ). Solid-state structures of 5c, 10, and 7b have been determined by single-crystal X-ray structural analysis.