Sorry but I can't help you. But I would like to put in evidence that your question is one of most important actual questions: Why a serie of important physical chemical data are available only from papers before Second War? Why people that use and need these data do not publish them? Sure that someone has some data. Mainly of the new compounds......

For solubilities of various kinds of metal-organic compounds use dry solvents like ether  or THF, DMF, acetonitrile etc.

Thank you, those are the solvents which I will try, I just wondered about the existence of a systematic database.

This will depend wildly on the kind of organometallic compound you are using.  When I worked on derivatives of Vaska's compound, we generally expected them to be soluble in THF, dichloromethane and toluene, and insoluble in diethyl ether, benzene, hexane and methanol.  When I worked on titanocene derivatives, they were readily soluble in hexane.

Dear Darren, I am interested in relatively simple compounds, as Ti(OR)4, Al(OR)3, VO(OR)3 and the like. I had some bad experiences with aluminium isopropoxide which should be soluble in isopropanol but I was not able to dissolve it completely in any solvent available to me. It may have been due to a partial hydolysis of Al(OiPr)3 - although I bought the sample from Sigma Aldrich.

The Merck Index assures me that aluminum isopropoxide is soluble in many alcohols and other organic solvents, so I suspect that your suspicions of hydrolysis are correct.  Titanium alkoxides will be similarly sensitive to hydrolysis (again, the Merck says that the isopropoxide will be soluble in dry alcohols, ether, benzene and chloroform).  I can think of no way of converting the hydrolyzed material back into the alkoxide, so your best bet would be the dissolve in absolutely dry solvent, then filter out anything that doesn't dissolve.

The solubility in different solvents will depend on the nature of the "R" group.  Bulky "R" groups will decrease the possibility of oligomerization and thus increase solubility.  The nature of the "R" group will also effect the solubility, with alkyl end groups imparting the most solubility in alkane solutions (and also to aryl and coordinating solvents), while aryl containing "R" groups will be somewhat less soluble in alkanes. Al (III), Ti (IV), and V (V) are hard acids, so solubility will be tuned to the specific "R" groups you are using.

The only thing that comes close to a "database" for inorganic complexes, to the best of my knowledge, is Gmelin database, which IIRC is updated by Elsevier.

Thank you for you valuable suggestions which were more or less in line with my expectations but it reduces the time of experimentation.

Most of the metal-organic compounds are found to be soluble in DMSO owing to its polarity. As per my experience, this if found to be true.

Dear Shilpa, thank you for your advice

I tried DMFA with 4 different compounds, it did not work. (Porbably partial hydrolysis)

Try aprotic highly polar solvents for solubility. Its better you distill the solvents prior use.