Reactions of cis and trans Bcat, aryl osmium complexes (cat=1,2-O2C6H4). Bis(Bcat) complexes of osmium and ruthenium and a structural comparison of cis and trans isomers of Os(Bcat)I(CO)(2)(PPh3)(2)

Reaction of Os(Bcat)Cl(CO)(PPh3)(2) (1) (HBcat = catecholborane or 1,3,2-be nzodioxaborole) with o-tolyllithium gives the yellow, five-coordinate Bcat, aryl complex Os(Bcat)(o-tolyl)(CO)(PPh3)(2) (2). Treatment of 2 with carbo n monoxide or p-tolylisocyanide gives the corresponding saturated Bcat, ary l complexes cis-Os(Bcat)(o-tolyl)(CO)(2)(PPh3)(2) (3) and cis-Os(Bcat)(o-to lyl)(CO)(CN-p-tolyl)(PPh3)(2) (4). Complexes 3 and 4 decompose in benzene s olution at room temperature to give o-tolylBcat and the orthometalated trip henylphosphine complexes Os(C6H4PPh2)H(CO)(2)(PPh3) (5) and Os(C6H4PPh2)H(C O)(CN-p-tolyl)(PPh3) (as a mixture of two isomers, 6a and 6b), respectively . In the presence of B(2)cat(2), 3 and 4 react to give the bis(Bcat) comple xes Os(Bcat)(2)(CO)(2)(PPh3)(2) (7) and Os(Bcat)(2)(CO)(CN-p-tolyl)(PPh3)(2 ) (8). Complex 3 also reacts with HBcat to produce Os(Bcat)H(CO)(2)(PPh3)(2 ) (9). The bis(Bcat) ruthenium complexes Ru(Bcat)(2)(CO)(2)(PPh3)(2) (10) a nd Ru(Bcat)(2)(CO)(CN-p-tolyl)(PPh3)(2) (11) can be prepared by treatment o f Ru(CO)(2)(PPh3)(3) or Ru(CO)(CN-p-tolyl)(PPh3)(3) with B(2)cat(2). Comple x 3 reacts with Cl2C=CCl2 or CHCl3 to produce OsCl(CCl=CCl2)(CO)(2)(PPh3)(2 ) (12) or OsCl2(CO)(2)(PPh3)(2), respectively. Complex 1 when treated with CQ gives cis-Os(Bcat)Cl(CO)(2)(PPh3)(2) (13), which in turn with phenyllith ium or o-tolyllithium gives trans-Os(Bcat)(Ph)(CO)(2)(PPh3)(2) (14) or tran s-Os(Bcat)(o-tolyl)(CO)(2)(PPh3)(2) (15). Complex 15 reacts with I-2 to giv e a mixture of trans-Os(Bcat)I(CO)(2)(PPh3)(2) (16) and trans-Os(o-tolyl)I( CO)(2)(PPh3)(2) (17). Complex 16 is also formed by heating cis-Os(Bcat)I(CO )(2)(PPh3)(2) (18) in benzene. Crystal structures of complexes, 5, 8, 10, 1 1, 12, 18, and 18 are reported.