The C [dbnd]O and C [dbnd]S bond cleavage in carbon dioxide and tolyl isothiocyanate by reactions with the Mo(0) tetraphosphine complex [Mo{ meso- o-C 6H 4(PPhCH 2CH 2PPh 2) 2}(Ph 2PCH 2CH 2PPh 2)

Abstract

A Mo(0) complex containing a new tetraphosphine ligand [Mo( P 4 )(dppe)] ( 1; P 4 = meso-o-C 6H 4(PPhCH 2CH 2PPh 2) 2, dppe = Ph 2PCH 2CH 2PPh 2) reacted with CO 2 (1 atm) at 60 °C in benzene to give a Mo(0) carbonyl complex fac-[Mo(CO)(η 3- P 4 O)(dppe)] ( 2), where the O abstraction from CO 2 by one terminal P atom in P 4 takes place to give the dangling P( O)Ph 2 moiety together with the coordinated CO. On the other hand, reaction of 1 with TolNCS (Tol = m-MeC 6H 4) in benzene at 60 °C resulted in the incorporation of three TolNCS molecules to the Mo center, forming a Mo(0) isocyanide–isothiocyanate complex trans, mer-[Mo(TolNC) 2(η 2-TolNCS)(η 3- P 4 S)] ( 4), where the S abstraction occurs from two TolNCS molecules by P 4 and dppe to give the η 3- P 4 S ligand and free dppe S, respectively, together with two coordinated TolNC molecules. The remaining site of the Mo center is occupied by the third TolNCS ligating at the C S bond in an η 2-manner. The X-ray analysis has been undertaken to determine the detailed structures for 2 and 4.