Russia was an ally of Iraq and worked hard to (unsuccessfully) try to defuse the situation from turning into an invasion.
They ultimately voted yes on the UN resolution authorizing the invasion after the US got Saudi Arabia to send $1bn to Russia in exchange for the vote.
Do you have a scholarly link detailing this bribe between Saudi Arabia/US and Moscow? It's the first I've ever heard of it, and in all of the historical analysis of the waning years of the Soviet Union and their role in shaping the modern Middle East, I'd imagine that this bribe would have been mentioned in top scholarly articles. For instance, in Alvin Rubinstein's "
Moscow and the Gulf War" it's not mentioned at all, and it's a pretty well detailed account of Gorbachev's positions on Iraq, Iran, Kuwait, and the US/UN.
Russia
was the key ally to Iraq, of course, all of the weapons, training, and financing of the invasion of Kuwait came from the USSR, and there were some ~5000 Soviet troops still in Iraq embedded with the Iraqi army as of 1990. The USSR sold Iraq about $23b worth of arms between '82 and '88, Iraq still owed about $6b in debt to the USSR by the end of the war, and the USSR had also been arming Kuwait in the 1980s as well, building Kuwait's missile defense system and protecting Kuwaiti ports & ships (largely not protecting Kuwait from Iraq, but from Iran; Kuwait and Iraq were allies until 1988) even allowing Kuwaiti ships to sail under the Soviet flag to avoid being attacked by Iran.
Still, while the USSR was the primary financier of war-making ability for Iraq, Gorbachev had already pivoted to American positions within the middle east by the late 1980s, and he did so because he thought that was best to preserve Moscow's role internationally and because of domestic internal pressure. Of course, at the same time as all of this the USSR had started to let member nations leave, the Soviet Union was collapsing, and Gorbachev was losing his own power domestically. Gorbachev wasn't an idiot, and while the USSR had had a defensive relationship with the UN and the security council for decades, by shifting to a supportive relationship of the UN, it would be an effective way to maintain influence and to cull American superiority. Gorbachev had shifted to these pro-UN positions back in 1987 and 1988 in public speeches and articles, well before Iraq's military build up on the border with Iraq or a purported Saudi Arabian bribe.
On August 2nd, the day that Iraq invaded and conquered Kuwait,
the Soviet government issued a statement "calling for the immediate and unconditional withdrawal of Iraqi troops from Kuwaiti territory. The sovereignty, national independence, and territorial integrity of Kuwait must by fully restored and defended." This was the same day as the invasion of Kuwait. Did Russia get this bribe from Saudi Arabia ahead of time? Eduard Shevardnadze, Russia's minister of Foreign Affairs, was "stunned" by the invasion and claimed, credibly, for decades later that the USSR had no advanced knowledge of invasion (Shrvardnadze would go onto become President of Georgia, and still maintained this position long after Gorbachev and the USSR was dead).
Despite supporting all UN resolutions around Iraq-Kuwait, Soviet Union/Russia/Moscow (I'm going with "Moscow" in my post because it's just easier than USSR or Russia) never took part in the military coalition against Iraq. Shevardnadze claimed at different times that the USSR might be sending troops or ships to the gulf, but they never did, and I don't think that's because of some ... effort at peace making, but that the USSR was in a tight spot... Thousands of Soviet soldiers were embedded in the Iraqi military, thousands of Soviet citizens were living in Iraq, and Gorbachev was concerned about domestic issues related to Soviet forces being on both sides of a war, where Soviet citizens working with the Iraqi military could become targets. Moscow would end up supporting the UN coalition in the months that followed, as part of larger cooperation between Moscow and the US, both financial aid (GWB agreed to provide financial aid to the USSR at the Helsinki conference in Sept 1990, but this was after Gorbachev had denounced Iraqi invasion).
Also confounding this is the internal conflict within domestic Soviet policies. Liberals in government were pushing for stronger relationship between the US and the USSR, conservatives were pushing for hardline antagonism, and conservatives were perceived to be losing this argument: Soviet military training and hardware (long a strategy promoted by Soviet conservatives and hawks) was being demolished on the battlefield, this just a couple years after an embarrassing withdrawal in Afghanistan. In a quixotic disruption to our perception of conservative vs. liberal, and east vs. west, capitalist vs. communist, it was domestic liberals within the USSR that supported military cooperation with the US & UN against Saddam Hussein:
(From "Moscow and the Gulf War," written by Graham Fuller, Foreign Affairs, 1991,
available for free on jstor)
I'm not saying that the position of Fyodor Burlatski is the right one, but that it was the liberal one within late stage Soviet politics, that ideological conservatives in the Soviet wanted to maintain a traditional relationship with Hussein and Iraq (as well as conservative positions domestically), while liberals were more interested in European and American engagement even on foreign policy. Gorbachev, trying to hold onto power while also trying to prevent the USSR from collapsing in on itself, tries to navigate the middle ground.
Russia would build a relationship with Saudi Arabia in the years after the war (as they would almost all financiers in the Middle East, post-Soviet Russia was in desperate need of foreign investment and took money from anyone offering it), but I can't find any evidence that Saudi Arabia bribed Gorbachev with $1b for him to condemn the Iraqi invasion of Kuwait and join the UN Security council vote, at least, no evidence from Russian or Cold War historians. The historical record, on the other hand, details the conflict within Soviet politics at the time where the old conservative guard -- that which supported Hussein from the 1970s and would come to be the primary benefactor for Iraq throughout the 1980s -- was being replaced by a progressive willingness to work with international organizations. I don't think it was always ideological, either, there was a practical benefit for Gorbachev to support American positions and support international institutions because it would strengthen Moscow's influence going forward. Russia would preserve the Soviet Union's permanent seat on the UN Security Council after all.