Com
plexes of the general formula[MXH
2(d
ppp)
2]
n+(M = Ru, Os; X = H, Cl, CO; d
ppp = 1,3-bis(di
phenyl
phos
phino)
pro
pane) have been
pre
pared and characterized,and the effect of the donor/acce
ptor
pro
pertiesof X on their structure and acidity has been studied. Thefive-coordinate com
plexes[MCl(d
ppp)
2]
+ (M = Ru(
1a), Os (
1b)) react with H
2 gas inCH
2Cl
2 to give the com
plexes[MCl(
2-H
2)(d
ppp)
2]
+(M = Ru (
2a), Os (
2b))containing elongated dihydrogen ligands. The molecular structureof
2b has been determined by X-raycrystallogra
phy (monoclinic, s
pace grou
pP2
1/
n with
a =13.314(7) Å,
b = 18.63(2) Å,
c =23.20(2) Å,
=94.58(6)
, and
Z = 4). Chlorohydride[OsH(Cl)(d
ppp)
2] (
3b) reacts withH
2 gas in the
presence ofNa[BPh
4]forming [OsH
3(d
ppp)
2]
+(
4b). Protonation of[OsH
2(d
ppp)
2] (
5b) withHBF
4·Et
2O also gives
4b.A combinationof X-ray crystallogra
phy (monoclinic, s
pace grou
pP2
1/
n with
a =13.392(3) Å,
b = 25.306(7) Å,
c =21.247(7)Å,
= 91.15(2)
, and
Z = 4) and
1H and
31P NMR studies indicate that
4b is a classical trihydride.Hydridocarbonyls[MH(CO)(d
ppp)
2]
+ (M = Ru(
6a), Os (
6b)) are
protonated byF
3CSO
3H inCD
2Cl
2 to yield[M(CO)(
2-H
2)(d
ppp)
2]
2+(M = Ru (
7a), Os (
7b)), which werecharacterized in solution.
7a is stable onlyatlow tem
perature. Com
pound
7b is a highly acidicdihydrogen com
plex with an estimated
pKa of-6.